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Objective: To assess the frequency and clinical characteristics of the increasingly recognised complication of cerebrovascular dysplasia in children with neurofibromatosis type 1 (NF1)., Methods: A series of seven patients with NF1 and cerebrovascular dysplasias that were not secondary to radiotherapy were identified and prospectively assessed. An extensive review of the literature was also performed to identify associated features and the natural history of this potentially severe complication of NF1., Results: The frequency of cerebrovascular dysplasia in NF1 was found to be 2-5%, and vascular lesions were clearly visible on routine MRI of the brain. The majority of patients were clinically asymptomatic, despite angiographic progression in some cases. Hypoplastic carotid canals and early appearance on MRI suggested that a proportion of cases of cerebrovascular dysplasia were congenital in origin., Conclusion: These findings have implications for screening of asymptomatic patients with NF1, and highlight the difficult management decisions in those patients identified with cerebrovascular malformations.

'We can now explain how this common genetic variation influences athletic performance as well as why it has become so common in the general population. There is a fascinating link between factors that influence survival in ancient humans and the factors that contribute to athletic abilities in modern man.' The human ACTN3 gene encodes the protein alpha-actinin-3, a component of the contractile apparatus in fast skeletal muscle fibers. In 1999, we identified a common polymorphism in ACTN3 (R577X) that results in absence of alpha-actinin-3 in more than one billion people worldwide, despite the ACTN3 gene being highly conserved during human evolution. In 2003, we demonstrated that ACTN3 genotype influences elite athletic performance, and the association between ACTN3 genotype and skeletal muscle performance has since been replicated in athletes and non-athlete cohorts. We have also studied the evolution of the R577X allele during human evolution and demonstrated that the null (X) allele has undergone strong, recent positive selection in Europeans and Asian populations. We have developed an Actn3 knockout mouse model that replicates alpha-actinin-3 deficiency in humans and has already provided insight into the role of alpha-actinin-3 in the regulation of skeletal muscle metabolism, fibre size, muscle mass and contractile properties. In particular, mouse muscle lacking alpha-actinin-3 uses energy more efficiently, with the fast fibers displaying metabolic and contractile properties of slow oxidative fibers. While this favors endurance activities, the trade off is that the muscle cannot generate the rapid contractions needed to excel in sprinting. We propose that the shift towards more efficient aerobic muscle metabolism associated with alpha-actinin-3 deficiency also underlies the adaptive benefit of the 577X allele. Our future studies will focus on the effect of ACTN3 genotype on response to exercise and ageing, and the onset and severity of muscle disease phenotype.

Objective: We aimed to determine the frequency of all known forms of congenital muscular dystrophy (CMD) in a large Australasian cohort., Methods: We screened 101 patients with CMD with a combination of immunofluorescence, Western blotting, and DNA sequencing to identify disease-associated abnormalities in glycosylated alpha-dystroglycan, collagen VI, laminin alpha2, alpha7-integrin, and selenoprotein., Results: A total of 45% of the CMD cohort were assigned to an immunofluorescent subgroup based on their abnormal staining pattern. Abnormal staining for glycosylated alpha-dystroglycan was present in 25% of patients, and approximately half of these had reduced glycosylated alpha-dystroglycan by Western blot. Sequencing of the FKRP, fukutin, POMGnT1, and POMT1 genes in all patients with abnormal alpha-dystroglycan immunofluorescence identified mutations in one patient for each of these genes and two patients had mutations in POMT2. Twelve percent of patients had abnormalities in collagen VI immunofluorescence, and we identified disease-causing COL6 mutations in eight of nine patients in whom the genes were sequenced. Laminin alpha2 deficiency accounted for only 8% of CMD. alpha7-Integrin staining was absent in 12 of 45 patients studied, and ITGA7 gene mutations were excluded in all of these patients., Conclusions: We define the distribution of different forms of congenital muscular dystrophy in a large cohort of mixed ethnicity and demonstrate the utility and limitations of current diagnostic techniques.

Low plasma levels of high-density lipoprotein cholesterol (HDL-C) are identified as a risk factor for cardiovascular disease (CVD). Sexual dimorphism, however, is widely reported in both HDL-C and CVD, with the underlying explanations of these sexual differences not fully understood. HDL-C is a complex trait influenced by both genes and dietary factors. Here we examine evidence for a sex-specific effect of APOE and the macronutrient carbohydrate on HDL-C, triglycerides (TG) and apoprotein A-1 (ApoA-1) in a sample of 326 male and 423 female participants of the Strong Heart Family Study (SHFS). Using general estimating equations in SAS to account for kinship correlations, stratifying by sex, and adjusting for age, body mass index (BMI) and SHS center, we examine the relationship between APOE genotype and carbohydrate intake on circulating levels of HDL-C, TG, and ApoA-1 through a series of carbohydrate-by-sex interactions and stratified analyses. APOE-by-carbohydrate intake shows significant sex-specific effects. All males had similar decreases in HDL-C levels associated with increased carbohydrate intake. However, only those females with APOE-4 alleles showed significantly lower HDL-C levels as their percent of carbohydrate intake increased, while no association was noted between carbohydrate intake and HDL-C in those females without an APOE-4 allele. These findings demonstrate the importance of understanding sex differences in gene-by-nutrient interaction when examining the complex architecture of HDL-C variation.

Aims/hypothesis: We hypothesised that TCF7L2 single nucleotide polymorphisms (SNPs) are associated with cardiovascular disease (CVD) and that the associations differ in diabetic and non-diabetic persons., Methods: Our analysis included black and white participants from the Atherosclerosis Risk in Communities study who were free of prevalent CVD at baseline and had been genotyped for rs7903146, rs12255372, rs7901695, rs11196205 and rs7895340 (n=13,369). Cox proportional hazard regression was used to estimate the associations between polymorphisms and incident events; logistic and linear regression were used for associations with baseline risk factor levels., Results: TCF7L2 SNPs were not significantly associated with incident coronary heart disease, ischaemic stroke, CVD, prevalent peripheral artery disease (PAD) or all-cause mortality in the full cohort or when stratified by race., Conclusions/interpretation: In the whole cohort, TCF7L2 SNPs were not associated with incident CVD, all-cause mortality or prevalent PAD. This result suggests that the increased health risk associated with rs7903146 genotype is specific to diabetes.

The congenital myopathies are defined by distinctive morphologic abnormalities in skeletal muscle. Over the past decade there have been major advances in defining the genetic basis of the majority of congenital myopathy subtypes, with increasing availability of genetic and prenatal diagnosis. Identification of the disease genes, in combination with a reappraisal of muscle pathology and the development of tissue culture and animal models is now providing insights into disease pathogenesis and, for the first time, suggesting avenues for the development of specific therapies. This review highlights some of the major recent advances in each of these areas and demonstrates how a morphological classification of the congenital myopathies into subgroups remains useful for future research into gene discovery and understanding of disease mechanism.

Background: Metabolic impairments that precede type 2 diabetes, such as metabolic syndrome, may contribute to the development of chronic kidney disease (CKD). This study documents the prevalence and incidence of CKD and the prospective association between metabolic syndrome and CKD in American Indians without diabetes in the Strong Heart Study., Study Design: Prospective cohort study., Setting & Participants: American Indians aged 45 to 74 years from 3 geographic regions were recruited by using tribal records and were assessed every 3 years from 1989 to 1999 as part of the Strong Heart Study. Participants with type 2 diabetes, on dialysis therapy, or who received a kidney transplant at baseline examination were excluded., Predictor: Metabolic syndrome, defined using Adult Treatment Panel III criteria., Outcomes & Measurements: CKD was measured by using estimated glomerular filtration rate (eGFR) and urinary albumin-creatinine ratio (ACR) dichotomized at conventional cutoff values. The association between metabolic syndrome and incident CKD was evaluated by using multivariable Cox proportional hazards models and binomial regression, with statistical adjustment for confounders (age, sex, study center, education, and smoking)., Results: Metabolic syndrome was present in 896 (37.7%) and absent in 1,484 participants (62.3%) at baseline. The prevalence of ACR of 30 mg/g or greater at baseline examination was 12.1%, with 290 new cases and an incidence of 233/10,000 person-years. The prevalence of eGFR less than 60 mL/min/1.73 m(2) was 7.8%, with 189 new cases and an incidence of 138/10,000 person-years. The prevalence of CKD was 17.8%, with 388 new cases and an incidence of 342/10,000 person-years. The adjusted hazard ratio for CKD associated with metabolic syndrome was 1.3 (95% confidence interval [CI], 1.1 to 1.6). Equivalent hazard ratios for ACR greater than 30 mg/g and eGFR less than 60 mL/min/1.73 m(2) were 1.4 (95% CI, 1.0 to 1.9) and 1.3 (95% CI, 1.0 to 1.6), respectively. The relationship between metabolic syndrome and kidney outcomes was stronger in those who developed diabetes during follow-up., Limitations: Intraindividual variability in serum creatinine and ACR measures may have resulted in some misclassification of participants by outcome status., Conclusions: Metabolic syndrome is associated with an increased risk of developing CKD in American Indians without diabetes. The mechanism through which metabolic syndrome may cause CKD in this population likely is the development of diabetes.

Cyclooxygenase-derived prostaglandins modulate cardiovascular disease risk. We genotyped 2212 Atherosclerosis Risk in Communities study participants (1,023 incident coronary heart disease (CHD) cases; 270 incident ischemic stroke cases; 919 non-cases) with available DNA for polymorphisms in PTGS1 and PTGS2. Using a case-cohort design, associations between genotype and CHD or stroke risk were evaluated using proportional hazards regression. In Caucasians, the reduced function PTGS1 -1006A variant allele was significantly more common among stroke cases compared to non-cases (18.2 versus 10.6%, P=0.027). In African Americans, the reduced function PTGS2 -765C variant allele was significantly more common in stroke cases (61.4 versus 49.4%, P=0.032). No significant relationships with CHD risk were observed. However, aspirin utilization appeared to modify the relationship between the PTGS2 G-765C polymorphism and CHD risk (interaction P=0.072). These findings suggest that genetic variation in PTGS1 and PTGS2 may be important risk factors for the development of cardiovascular disease events. Confirmation in independent populations is necessary.

Nemaline myopathies (NM) are a rare group of muscle disorders, but represent one of the most common forms of congenital myopathy. The clinical picture ranges from severe muscular hypotonia often leading to death during childhood to mild forms with long life expectancy. Diagnosis is made by muscle biopsy showing characteristic sarcoplasmic and sometimes intranuclear rod bodies. So far, disease-associated mutations have been detected in six genes without any simple correlation between genotype and phenotype or histological findings. We report a patient with a phenotype typical of congenital onset nemaline myopathy and exclusively intranuclear rods. Mutation analysis revealed a new heterozygous missense mutation in exon 3 of the ACTA1 gene (Q139H). Molecular modelling predicts that substitution of Q139 for H139 alters the amino acid side chains and hydrogen bonding which may alter the nucleotide binding cleft by adding 'bulk' to the mutated molecule. Two-dimensional gel electrophoresis demonstrates that mutant actin Q139H is expressed at approximately half the level of wild-type actin in the patient's muscle. We speculate that these alterations, although not directly affecting the nuclear export signal, negatively interfere with the nuclear export of the mutated protein and thereby cause retention of mutant actin and intranuclear rod formation.

Purpose: To determine the frequency of the ACTN3 R577X polymorphism (functional R allele and nonfunctional X allele) in a variety of African populations and to examine its influence on the success of elite East African endurance runners and West African sprinters., Methods: The R577X polymorphism was genotyped in 198 Ethiopian controls and 76 elite Ethiopian endurance athletes, 158 Kenyan controls and 284 elite Kenyan endurance runners, and 60 Nigerian controls and 62 elite Nigerian power athletes. Statistical analyses were performed by exact tests of population differentiation, using Arlequin, version 3. Analyses were carried out using 1 x 10(6) Markov chain steps, and 1 x 10(5) dememorization steps., Results: The frequency of the X allele was extremely low among Kenyans and Nigerians (approximately 1% homozygosity) and higher in Ethiopians (approximately 11% homozygosity). The low baseline frequencies of the three populations tested mean that any associations with sprint performance would likely be obscured. In Ethiopians, where baseline levels of 577XX were about 11%, there was no increased frequency in the endurance athletes., Conclusion: Our data suggest that alpha-actinin-3 deficiency is not a major influence on performance in African athletes.

Muscular dystrophies with reduced glycosylation of alpha-dystroglycan (alpha-DG), commonly referred to as dystroglycanopathies, are a heterogeneous group of autosomal recessive conditions which include a wide spectrum of clinical severity. Reported phenotypes range from severe congenital onset Walker-Warburg syndrome (WWS) with severe structural brain and eye involvement, to relatively mild adult onset limb girdle muscular dystrophy (LGMD). Specific clinical syndromes were originally described in association with mutations in any one of six demonstrated or putative glycosyltransferases. Work performed on patients with mutations in the FKRP gene has identified that the spectrum of phenotypes due to mutations in this gene is much wider than originally assumed. To further define the mutation frequency and phenotypes associated with mutations in the other five genes, we studied a large cohort of patients with evidence of a dystroglycanopathy. Exclusion of mutations in FKRP was a prerequisite for participation in this study. Ninety-two probands were screened for mutations in POMT1, POMT2, POMGnT1, fukutin and LARGE. Homozygous and compound heterozygous mutations were detected in a total of 31 probands (34 individuals from 31 families); 37 different mutations were identified, of which 32 were novel. Mutations in POMT2 were the most prevalent in our cohort with nine cases, followed by POMT1 with eight cases, POMGnT1 with seven cases, fukutin with six cases and LARGE with only a single case. All patients with POMT1 and POMT2 mutations had evidence of either structural or functional central nervous system involvement including four patients with mental retardation and a LGMD phenotype. In contrast mutations in fukutin and POMGnT1 were detected in four patients with LGMD and no evidence of brain involvement. The majority of patients (six out of nine) with mutations in POMT2 had a Muscle-Eye-Brain (MEB)-like condition. In addition we identified a mutation in the gene LARGE in a patient with WWS. Our data expands the clinical phenotypes associated with POMT1, POMT2, POMGnT1, fukutin and LARGE mutations. Mutations in these five glycosyltransferase genes were detected in 34% of patients indicating that, after the exclusion of FKRP, the majority of patients with a dystroglycanopathy harbour mutations in novel genes.

Background: CCR5 and CCR2 gene polymorphisms (SNPs) have been associated with protection against HIV transmission in adults and with delayed progression to AIDS. The CCR5 Delta32 deletion and SNP -2459G are associated with reduced expression of the CCR5 protein., Methodology/principal Findings: We investigated the association between infant CCR2/CCR5 diplotype and HIV mother to child transmission (MTCT) in Malawi. Blood samples from infants (n = 552) of HIV positive women who received nevirapine were genotyped using a post-PCR multiplex ligase detection reaction and haplotypes were identified based on 8 CCR2/CCR5 SNPs and the open reading frame 32 base pair deletion. Following verification of Hardy-Weinberg equilibrium, log linear regression was performed to examine the association between mutations and MTCT. Overall, protection against MTCT was weakly associated with two CCR5 SNPs, -2459G (Risk ratio [RR], 0.78; confidence interval [CI], 0.54-1.12), and the linked CCR5 -2135T (RR, 0.78; CI, 0.54-1.13). No child carried the CCR5 Delta32 SNP. Maternal Viral Load (MVL) was found to be an effect measure modifier. Among mothers with low MVL, statistically significant protection against MTCT was observed for -2459G (RR, 0.50; CI, 0.27-0.91), and -2135T (RR, 0.51; CI, 0.28-0.92). Statistically significant protection was not found at high MVL., Conclusions/significance: Results from this study suggest that CCR5 SNPs -2459G and -2135T associated with reduced receptor expression protect against MTCT of HIV at low MVLs, whereas high MVLs may over-ride differences in coreceptor availability.

Background: Neurofibromatosis type 1 (NF1) is a genetic disorder associated with cognitive deficits, learning problems, medical complications and cosmetic disfigurement. Despite the wide-ranging impact of NF1, very few studies have examined the psychosocial adjustment of individuals with NF1, and in particular, self-concept. The aims of this study were threefold: (i) to examine the self-concept of children and adolescents with NF1; (ii) to compare the self-concept of children with NF1 (NF1 only), children with NF1 and learning difficulties [NF1 + LA (low achievement)], and children with NF1 and attention deficit hyperactivity disorder (ADHD) (NF1 + ADHD); and (iii) to examine the academic self-concept of these three groups relative to objective criteria - academic achievement and teacher ratings of academic competence., Methods: Measures of self-concept, academic achievement and intelligence were administered to 49 children and 26 adolescents with NF1. Parents and teachers completed behavioural rating scales., Results: The majority of children and adolescents with NF1 reported positive global self-concept, with some exceptions on specific domains. Children and adolescents with NF1 reported significantly poorer self-concept for physical abilities. Adolescents also reported significantly poorer self-concept for mathematics and general self when compared with normative mean values. Clinical severity of NF1 was not a significant predictor of self-concept for physical appearance or physical abilities. Despite a significant difference between NF1 only, NF1 + LA and NF1 + ADHD groups on measures of academic achievement and teacher ratings of academic competence, there was no significant difference between the groups for academic domains of self-concept, or any other domain of self-concept. All three groups reported inflated academic self-perceptions relative to objective criteria., Conclusion: Children and adolescents with NF1 are most likely to develop negative self-concepts about their physical and sporting abilities. Inflated academic self-perceptions are discussed in light of the positive illusory bias, which may serve as an adaptive or protective function.

Background: Calcified coronary plaque (CCP) is a complex trait influenced by both genes and environment, and plausibly an interaction between the two. Because the familial aggregation of CCP has been demonstrated and smoking is a significant, independent predictor of CCP, we assessed the evidence for genotype-by-smoking interaction and conducted linkage analysis of quantitative Agatston CCP scores in participants of the NHLBI Family Heart Study (FHS)., Methods: During standardized clinical exams smoking habits were ascertained and CCP was quantified with cardiac computed tomography (CT). Among 4387 relationship pairs from 2128 Caucasian examinees variance component analysis was implemented in SOLAR to examine: (1) additive genotype-by-smoking status interaction using a variance component approach; (2) linkage analysis in the full sample and among smoking subsets defined by individual smoking exposure; (3) QTL-specific genotype-by-smoking interaction in the regions that appeared to differentiate between smoking strata., Results: The prevalence of CCP (and median Agatston score) was 75% (184.6) in men and 48% (51.0) in women. We detected four genome-wide significant logarithm of odds (LOD) scores in samples stratified by individual smoking exposure: chromosome 4 at 122cM (nearest marker D4S2297; robust adjusted LOD=3.1; q=0.053), chromosome 6 at 99cM (nearest marker D6S1056; robust adjusted LOD=3.3; q=0.053), chromosome 11 at 19cM (nearest marker D11S199; robust adjusted LOD=4.0; q=0.02) and chromosome 13 at 77cM (nearest marker D13S892; robust adjusted LOD=3.1; q=0.053). Additive and QTL-specific genotype-by-smoking interaction was detected on chromosomes 4, 6, 11 and 13; all P<0.05. Three of the four QTLs identified in this report have been previously linked to atherosclerosis and harbor interesting candidate genes., Conclusions: These findings demonstrate the importance of considering complex interactions in the search for genes that influence the pathogenesis of CCP.

Objective: Mutations in ACTA1 have been associated with a variety of changes in muscle histology that likely result from fundamental differences in the way that ACTA1 mutations disrupt muscle function. Recently, we reported three patients with congenital fiber type disproportion (CFTD) caused by novel heterozygous missense mutations in ACTA1 (D292V, L221P, P332S) with marked type 1 fiber hypotrophy as the only pathological finding on muscle biopsy. We have investigated the basis for the histological differences between these CFTD patients and patients with ACTA1 nemaline myopathy (NM)., Methods and Results: Mass spectrometry and two-dimensional gel electrophoresis demonstrate that mutant actin accounts for 25 and 50% of alpha-skeletal actin in the skeletal muscle of patients with the P332S and D292V mutations, respectively, consistent with a dominant-negative disease mechanism. In vitro motility studies indicate that abnormal interactions between actin and tropomyosin are the likely principal cause of muscle weakness for D292V, with tropomyosin stabilized in the "switched off" position. Both the D292V and P322S CFTD mutations are associated with normal sarcomeric structure on electron microscopy, which is atypical for severe NM. In contrast, we found no clear difference between ACTA1 mutations associated with NM and CFTD in tendency to polymerize or aggregate in C2C12 expression models., Interpretation: These data suggest that ACTA1 CFTD mutations cause weakness by disrupting sarcomere function rather than structure. We raise the possibility that the presence or absence of structural disorganization when mutant actin incorporates into sarcomeres may be an important determinant of whether the histological patterns of CFTD or NM develop in ACTA1 myopathy.

Objective: To assess the effect of institution of noninvasive ventilation (NIV) on clinical outcome and quality of life (QOL) in a cohort of children with severe neuromuscular disorders., Methods: We reviewed records and obtained clinical data from the year prior to commencing NIV and annually thereafter. Data obtained included diagnosis, patient symptoms, mortality, NIV adverse effects, pulmonary function tests, polysomnographic data, length of hospitalizations, and health care costs. Patients and parents completed questionnaires assessing QOL with NIV and recalling QOL before NIV., Results: Fourteen of 17 (82%) suitable patients were enrolled. Follow-up ranged from 6 to 84 months (median 30). Symptoms of daytime sleepiness (p = 0.003) and headache (p = 0.046) improved after initiation of NIV. Sleep quality assessed by polysomnography also improved. Hospitalization rates (p = 0.002) and health care costs (p = 0.003) decreased. QOL remained stable after NIV, despite disease progression., Conclusion: Treatment of respiratory failure, in children with neuromuscular disease, with noninvasive ventilation results in a reduction in symptoms, hospitalizations, and health care costs without adverse effects on quality of life.

The functional allele (577R) of ACTN3, which encodes human alpha-actinin-3, has been reported to be associated with elite athletic status and with response to resistance training, while the nonfunctional allele (577X) has been proposed as a candidate metabolically thrifty allele. In a study of 992 adolescent Greeks, we show that there is a significant association (P=0.003) between the ACTN3 R577X polymorphism and 40 m sprint time in males that accounts for 2.3% of phenotypic variance, with the 577R allele contributing to faster times in an additive manner. The R577X polymorphism is not associated with other power phenotypes related to 40 m sprint, nor with an endurance phenotype. Furthermore, the polymorphism is not associated with obesity-related phenotypes in our population, suggesting that the 577X allele is not a thrifty allele, and thus the persistence of this null allele must be explained in other terms.

Background: We report longitudinal changes in the metabolic syndrome (MetS) in 2,458 participants from 480 families in the Family Heart Study. Participants were examined between 1994-96 (FHS-T1) and 2002-03 (FHS-T2), about 7.4 years apart. Additionally, the impact of medication on estimates of MetS prevalence, and associations of MetS with prevalent coronary heart disease (CHD) and type 2 diabetes (T2D) were studied., Methods: Three definitions for MetS prevalence were considered. One represented the original (o) National Cholesterol Education Program (NCEP) MetS criteria. Two others considered the confounding of medications effects, respectively (m) lipid medications constituted a categorical diagnostic criterion for lipids variables, and (c) lipids and blood pressure variables were corrected with average clinical trials medications effects. Logistic regression of MetS on CHD and T2D, as well as the trend analysis of MetS by age, were performed., Results: MetS increased from 17.1% in FHS-T1(o) to 28.8% in FHS-T2(o); from 19.7% in FHS-T1(m) to 42.5% in FHS-T2(m); and from 18.4% in FHS-T1(c) to 33.6% in FHS-T2(c). While we observed adverse changes in all risk factors, the greatest increase was for waist circumference (25%). The percentages of MetS were about 2 to almost 3 times higher in ages 50 years and older than in younger ages. The odds of having prevalent CHD were about 2.5 times higher in the subjects classified with MetS than without., Conclusion: MetS percentages increased noticeably longitudinally and cross-sectionally with older age. These conclusions were reached with and without considering medication use, but correcting risk factors for medications use affects the MetS prevalence estimates. As found in other studies, MetS was associated with increased odds for prevalent CHD.

Aims/hypothesis: While there are sex-related differences in both the prevalence of type 2 diabetes mellitus and disease risk factors, there is only limited research on sex-specific influences on type 2 diabetes aetiology within the same study population. Thus, we assessed genotype-by-sex interaction using a liability threshold model in an attempt to localise sex-specific type 2 diabetes quantitative trait loci (QTLs)., Subjects, Materials and Methods: Hypertensive siblings and their offspring and/or parents in the Hypertension Genetic Epidemiology Network of the Family Blood Pressure Program were recruited from five field centres. The diabetic phenotype was adjusted for race, study centre, age and non-linear age effects. In total, 567 diabetic individuals were identified in 385 families. Variance component linkage analyses in the combined sample and stratified by sex and race were performed (SOLAR program) using race-specific marker allele frequencies derived from a random sample of participants at each centre., Results: We observed a QTL-specific genotype-by-sex interaction (p=0.009) on chromosome 17 at 31 cM, with females displaying a robust adjusted logarithm of odds (LOD) of 3.0 compared with 0.2 in males and 1.3 in the combined sample. Three additional regions demonstrating suggestive evidence for linkage were detected: chromosomes 2 and 5 in the female sample and chromosome 22 (adjusted LOD=1.9) in the combined sample., Conclusions/interpretation: These findings suggest that multiple genes may regulate susceptibility to type 2 diabetes, demonstrating the importance of considering the interaction of genes and environment in the aetiology of common complex traits.

Estimating the effects of haplotypes on the age of onset of a disease is an important step toward the discovery of genes that influence complex human diseases. A haplotype is a specific sequence of nucleotides on the same chromosome of an individual and can only be measured indirectly through the genotype. We consider cohort studies which collect genotype data on a subset of cohort members through case-cohort or nested case-control sampling. We formulate the effects of haplotypes and possibly time-varying environmental variables on the age of onset through a broad class of semiparametric regression models. We construct appropriate nonparametric likelihoods, which involve both finite- and infinite-dimensional parameters. The corresponding nonparametric maximum likelihood estimators are shown to be consistent, asymptotically normal, and asymptotically efficient. Consistent variance-covariance estimators are provided, and efficient and reliable numerical algorithms are developed. Simulation studies demonstrate that the asymptotic approximations are accurate in practical settings and that case-cohort and nested case-control designs are highly cost-effective. An application to a major cardiovascular study is provided.

Residents living in communities near Superfund sites have expressed concern that releases from these facilities affect their health, including adverse effects on their immune systems. We used data from six cross-sectional studies to evaluate whether people who live near several Superfund sites are more likely to have individual immunoglobulin test results (IgA, IgG, and IgM) below or above the reference range than those who live in comparison areas with no Superfund site. Study participants consisted of target-area residents who lived close to a Superfund site and comparison-area residents who were not located near any Superfund or hazardous waste sites. A consistent modeling strategy was used across studies to assess the magnitude of the relationship between area of residence and immunoglobulin test results, adjusting for potential confounders and effect modifiers. In all study areas, the results suggest that people who live near a Superfund site may have been more likely to have IgA test results above the reference range than comparison areas residents regardless of modeling strategy employed. The effect measures were larger for residents who lived in communities near military bases with groundwater contamination. For all analyses the wide confidence intervals reflect uncertainty in the magnitude of these effects. To adequately address the question of whether the immune system is affected by low-level exposures to hazardous substances, we recommend that more functional immunotoxicity tests be conducted in human populations where individual exposure information is available or when it can be reasonably estimated from environmental exposure measurements.

To localize quantitative trait loci for insulin metabolism and obesity, genome scans/linkage analyses were performed on >900 members of 32 extended families participating in phase 3 of the Strong Heart Study, an investigation of the genetic and environmental determinants of cardiovascular disease in American-Indian populations from Arizona, Oklahoma, and North and South Dakota. Linkage analyses of fasting insulin and two obesity-related phenotypes, BMI and percent fat mass, were performed independently in each of the three populations. For log fasting insulin, we found a genome-wide maximum, robust logarithm of odds (LOD) score of 3.42 at 51 cM on chromosome 2p in the Dakotas. Bivariate linkage analyses of log fasting insulin with both BMI and fat mass indicate a situation of incomplete pleiotropy, as well as several significant bivariate LOD scores in the Dakotas.

A case of rippling muscle disease is presented and features of this rare condition, and its association with caveolin-3 are discussed.

Studies have reported a lower burden of calcified atherosclerotic plaque in coronary arteries in African-Americans than in whites. Findings from autopsy studies of sudden cardiac death have suggested a link between left ventricular hypertrophy and severity of coronary atherosclerosis. Echocardiograms and cardiac computed tomograms were analyzed in 334 African-American (84% hypertensive) and 196 white (66% hypertensive) adults with no history of coronary heart disease or revascularization procedures at study entry. The relation of coronary artery calcium (CAC) score to left ventricular mass and left ventricular mass indexed to body surface area was assessed by Spearman's correlations and mixed linear models. Covariates included age, gender, field center, weight, height, systolic blood pressure, number of antihypertensive medications, diabetes, total and high-density lipoprotein cholesterol levels, and current smoking and alcohol consumption. In African-Americans, a significant and independent association between CAC score and left ventricular mass or left ventricular mass indexed to body surface area was present with the 2 analytic strategies. Spearman's correlation coefficients for CAC score with left ventricular mass and left ventricular mass indexed to body surface area were 0.14 (p = 0.015) and 0.13 (p = 0.025), respectively, after multivariable adjustment. In whites, the associations of CAC score with measurements of left ventricular mass were weaker and only marginally significant in mixed linear models. In conclusion, these findings suggest that CAC reflects a different risk burden between African-Americans and whites, and future studies examining the prognostic implications of CAC in African-Americans should consider the potential association between CAC and left ventricular hypertrophy.

In this article we report a novel statistically significant association between the D4.7/D4.7 genotype of the DRD4 gene and the body mass of black and Hispanic participants in the National Longitudinal Study of Adolescent Health (Add Health). We investigated the role of the 48-bp repeat polymorphism of the dopamine receptor 4 gene (DRD4) in body mass regulation in 2,277 adolescents and young adults followed in 1995 (12-18 years old), 1996, and 2002 by Add Health. After the effects of age, sex, and ethnicity were adjusted, the D4.7/D4.7 genotype reduced the body mass index (BMI)-percentile score by 15 and 12.5, as compared to those with other genotypes, for African-Americans (P = 0.0047) and Hispanic-Americans (P = 0.037), respectively. Although the D4.7/D4.7 genotype was associated with a lower BMI-percentile score in white individuals compared to other genotypes, the difference was not significant. Individuals heterozygous for D4.7 did not differ from those with the other/other genotype., (2006 Wiley-Liss, Inc.)

Previous studies have demonstrated that low density lipoprotein cholesterol (LDL-C) concentration is influenced by both genes and environment. Although rare genetic variants associated with Mendelian causes of increased LDL-C are known, only one common genetic variant has been identified, the apolipoprotein E gene (APOE). In an attempt to localize quantitative trait loci (QTLs) influencing LDL-C, we conducted a genome-wide linkage scan of LDL-C in participants of the Strong Heart Family Study (SHFS). Nine hundred eighty men and women, age 18 years or older, in 32 extended families at three centers (in Arizona, Oklahoma, and North and South Dakota) were phenotyped for LDL-C concentration and other risk factors. Using a variance component approach and the program SOLAR, and after accounting for the effects of covariates, we detected a QTL influencing LDL-C on chromosome 19, nearest marker D19S888 at 19q13.41 [logarithm of odds (LOD) = 4.3] in the sample from the Dakotas. This region on chromosome 19 includes many possible candidate genes, including the APOE/C1/C4/C2 gene cluster. In follow-up association analyses, no significant evidence for an association was detected with the APOE*2 and APOE*4 alleles (P = 0.76 and P = 0.53, respectively). Suggestive evidence of linkage to LDL-C was detected on chromosomes 3q, 4q, 7p, 9q, 10p, 14q, and 17q. These linkage signals overlap positive findings for lipid-related traits and harbor plausible candidate genes for LDL-C.

SIL1 (also called BAP) acts as a nucleotide exchange factor for the Hsp70 chaperone BiP (also called GRP78), which is a key regulator of the main functions of the endoplasmic reticulum. We found nine distinct mutations that would disrupt the SIL1 protein in individuals with Marinesco-Sjögren syndrome, an autosomal recessive cerebellar ataxia complicated by cataracts, developmental delay and myopathy. Identification of SIL1 mutations implicates Marinesco-Sjögren syndrome as a disease of endoplasmic reticulum dysfunction and suggests a role for this organelle in multisystem disorders.

Low levels of high-density lipoprotein (HDL) are widely documented as a risk factor for cardiovascular disease (CVD). Furthermore, there is marked sexual dimorphism in both HDL levels and the prevalence of CVD. However, the extent to which genetic factors contribute to such dimorphism has been largely unexplored. We examined the evidence for genotype-by-sex effects on HDL in a longitudinal sample of 1562 participants from 330 families in the Framingham Heart Study at three times points corresponding approximately to 1971-1974, 1980-1983, and 1988-1991. Using a variance component method, we conducted a genome scan of HDL at each time point in males and females, separately and combined, and tested for genotype-by-sex interaction at a quantitative trait locus (QTL) at each time point. Consistent findings were noted only for females on chromosome 2 near marker D2S1328, with adjusted LOD scores of 2.6, 2.2, and 2.1 across the three time points, respectively. In males suggestive linkage was detected on chromosome 16 near marker D16S3396 at the second time point and on chromosome 18 near marker D18S851 at the third time point (adjusted LOD = 2.2 and 2.4, respectively). Although the heritability of HDL is similar in males and females, sex appears to exert a substantial effect on the QTL-specific variance of HDL. When genotype-by-sex interactions exist and are not modeled, the power to detect linkage is reduced; thus our results may explain in part the paucity of significant linkage findings for HDL.

Objective: To conduct a full genome search for genes potentially influencing two related phenotypes: body mass index (BMI, kg/m2) and percent body fat (PBF) from bioelectric impedance in men and women., Design: A total of 3383 participants, 1348 men and 2035 women; recruitment was initiated with hypertensive sibpairs and expanded to first-degree relatives in a multicenter study of hypertension genetics., Measurements: Genotypes for 387 highly polymorphic markers spaced to provide a 10 cM map (CHLC-8) were generated by the NHLBI Mammalian Genotyping Service (Marshfield, WI, USA). Quantitative trait loci for obesity phenotypes, BMI and PBF, were examined with a variance components method using SOLAR, adjusting for hypertensive status, ethnicity, center, age, age2, sex, and age2 x sex. As we detected a significant genotype-by-sex interaction in initial models and because of the importance of sex effects in the expression of these phenotypes, models thereafter were stratified by sex. No genotype-by-ethnicity interactions were found., Results: A QTL influencing PBF in women was detected on chromosome12q (12q24.3-12q24.32, maximum empirical LOD score=3.8); a QTL influencing this phenotype in men was found on chromosome 15q (15q25.3, maximum empirical LOD score=3.0). These QTLs were detected in African-American and white women (12q) and men (15q). QTLs influencing both BMI and PBF were found over a broad region on chromosome 3 in men. QTLs on chromosomes 3 and 12 were found in the combined sample of men and women, but with weaker significance., Conclusion: The locations with highest LOD scores have been previously reported for obesity phenotypes, indicating that at least two genomic regions influence obesity-related traits. Furthermore, our results indicate the importance of considering context-dependent effects in the search for obesity QTLs.

We report muscle MRI findings of 10 patients from 8 families with nemaline myopathy. Patients with involvement of the nebulin (NEB) gene showed a consistent pattern of selective muscle involvement corresponding to clinical severity. In mild cases, there was complete sparing of thigh muscles and selective involvement of tibialis anterior and soleus. In moderate cases, there was predominant involvement of rectus femoris, vastus lateralis and hamstring muscles and diffuse involvement of anterior compartment and soleus. Patients with nemaline myopathy secondary to mutations in the skeletal muscle alpha-actin (ACTA1) gene showed diffuse involvement of thigh and leg muscles with relative sparing of the gastrocnemii. Selective muscle involvement in both genetic categories was distinct from what has been reported in other congenital myopathies. We conclude that muscle MRI may be applied to distinguish nemaline myopathy from other conditions with similar clinical and histopathological features, to supplement clinical assessment in individual patients and to help direct genetic testing.

Assessment of haemostasis in people with neurofibromatosis type 1 (NF-1) is essentially lacking, despite case reports of an association with von Willebrand disorder (VWD) and reported excessive bleeding post-surgery. We assessed routine blood haematology, routine coagulation parameters [prothrombin time (PT), activated partial thromboplastin time (APTT), thrombin time (TT) and fibrinogen], coagulation factors II, V, VII, VIII, IX, X, XI and XII, von Willebrand (VWF) factor antigen and activity, and platelet function [using the platelet function analyser (PFA-100)] in a group of individuals with NF-1 (n = 30). Their perceived haemorrhagic bleeding risk was also graded by means of a structured clinical assessment and physical examination. Routine blood assessments including platelet counts were generally normal, as were the routine coagulation tests PT, TT and fibrinogen, and most coagulation factors. Elevated APTTs were detected in 11 individuals, reduced factor XII levels in three, reduced VWF levels in four, and elevated PFA closure times (CTs) in 13. Laboratory results correlated with each other in some but not all cases. For example, elevated APTTs were identified in two of three individuals with a reduced factor XII level and prolonged CTs were identified in three individuals who also showed reduced aggregation responses in classical platelet function studies. Moreover, all individuals with VWF results below the normal reference range showed elevated CTs with both PFA test cartridges, and those with VWF results identified as borderline normal (i.e. 50-65%) also showed elevated CTs with both PFA test cartridges in three of five cases. The relationship between VWF and CTs was also identified by linear regression analysis (P-values of <0.05, for all comparisons). However, as clinically perceived bleeding risk did not appear to be correlated with laboratory test results in most cases, blanket screening of NF-1 individuals for evaluation of laboratory haemostasis may not be warranted.

Children with neurofibromatosis type 1 (NF1) have difficulties in forming friendships and are often rejected by their peers. Factors that contribute to these negative social outcomes are poorly understood. This study investigated the social skills of children with NF1 and the influence of comorbid conditions, such as attention-deficit-hyperactivity disorder (ADHD) and specific learning dfficulties. We assessed and analyzed data from 79 children with NF1 (42 males, 37 females; mean age 11 years 6 months, SD 2 years 4 months) and 46 unaffected siblings (19 males, 27 females; mean age 12 years 1 month, SD 2 years 6 months; age range 8 to 16 years). Social skills were measured with the Social Skills Rating System. Children with NF1 had significantly poorer social outcomes than their unaffected siblings, and significantly poorer social skills in comparison with normative data. The presence of ADHD (in 39% of children with NF1) was the major risk factor for poor social functioning. Children with NF1 and ADHD had the poorest social skills and social outcomes when compared with children with NF1 only or children with NF1 and learning difficulties. These findings dispel the previous assumption that NF1 alone is associated with poor social functioning and has major implications for the development of effective interventions.

We describe a simple culture method for obtaining highly differentiated clonal C2C12 myotubes using a feeder layer of confluent fibroblasts, and document the expression of contractile protein expression and aspects of myofibre morphology using this system. Traditional culture methods using collagen- or laminin-coated tissue-culture plastic typically results in a cyclic pattern of detachment and reformation of myotubes, rarely producing myotubes of a mature adult phenotype. C2C12 co-culture on a fibroblast substratum facilitates the sustained culture of contractile myotubes, resulting in a mature sarcomeric register with evidence for peripherally migrating nuclei. Immunoblot analysis demonstrates that desmin, tropomyosin, sarcomeric actin, alpha-actinin-2 and slow myosin are detected throughout myogenic differentiation, whereas adult fast myosin heavy chain isoforms, members of the dystrophin-associated complex, and alpha-actinin-3 are not expressed at significant levels until >6 days of differentiation, coincident with the onset of contractile activity. Electrical stimulation of mature myotubes reveals typical and reproducible calcium transients, demonstrating functional maturation with respect to calcium handling proteins. Immunocytochemical staining demonstrates a well-defined sarcomeric register throughout the majority of myotubes (70-80%) and a striated staining pattern is observed for desmin, indicating alignment of the intermediate filament network with the sarcomeric register. We report that culture volume affects the fusion index and rate of sarcomeric development in developing myotubes and propose that a fibroblast feeder layer provides an elastic substratum to support contractile activity and likely secretes growth factors and extracellular matrix proteins that assist myotube development., (Copyright 2004 Wiley-Liss, Inc.)

Cardiovascular reactivity is hypothesized to increase the risk of hypertension and other CVD-related conditions. However, studies to date are inconclusive. We compared the association of blood pressure and pulse responses to three stressors (postural challenge, handgrip test, mental arithmetic) with sociodemographic characteristics and CVD risk factors. We included 782 participants from the Hypertension Genetic Epidemiology Study. Blood pressure and pulse responses to stressors were defined as the difference between post- and pre-stress measurements. Stepwise regression analyses examined change in SBP and pulse in response to stressors as a function of sociodemographic and CVD risk factors. Age, race, and gender were forced into models and other variables (education, BMI, waist circumference, resting SBP and DBP, cigarette smoking, LDL and HDL cholesterol, glucose, and antihypertensive medications (beta-blockers, calcium channel blockers, diuretics, ace inhibitors)) were retained if P<0.10. Age was a significant predictor of SBP response to all stressors. The SBP response to a change in posture was not related to other variables. The SBP response to mental arithmetic was significantly higher among men, those with larger waists, higher SBP, beta-blocker users, and lower among smokers. SBP response to the handgrip was significantly higher among those with higher SBP and beta-blocker users. Similarly, the association of the pulse response to the risk factors varied considerably across the stressors. Overall, the socio-demographic and CVD risk factors accounted for between 9 and 14% of the variance in the SBP response to the stressors and from between 4 and 12% of the variance in the pulse response to the three stressors. The associations between sociodemographic and CVD risk factors and the SBP and pulse response to stress were modest and inconsistent across stressors. The findings suggest that cardiovascular reactivity is a concept that needs to be defined in reference to specific stressors so that mechanisms leading to responses can be better understood.

Objective: To describe the natural history of optic pathway gliomas (OPGs) in patients with neurofibromatosis type 1 (NF1), and to evaluate the current recommended guidelines for monitoring and follow-up of OPGs in this population., Design: Retrospective case series., Participants: Patients with OPGs and NF1 seen in the neurofibromatosis clinic at the Children's Hospital at Westmead in Sydney, Australia., Methods: Patients with definite NF1 and confirmed OPGs were identified and their medical records searched to obtain data on demographics, details of the OPG diagnosis, and serial ophthalmic examination findings. Patients were stratified into groups according to age and mode of presentation., Main Outcome Measures: Visual acuity was recorded for each eye and grouped into mild (Snellen equivalent > or = 6/12), moderate (Snellen equivalent = 6/15-6/60), and severe (Snellen equivalent < 6/60) visual impairment at time of diagnosis, during follow-up, and at the most recent examination., Results: Data were collected on 54 patients, the majority of whom (78%) were seen from 1990 to 2002, with an average follow-up of 8.6 years. The mean age at the time of OPG diagnosis was 5.2 years, with 32 patients having symptoms or signs at the time of diagnosis. Seventeen patients were diagnosed after the age of 6 years (range, 7-15). Twenty-two patients had tumor progression within 1 year of diagnosis, and a further 6 patients showed progression after 1 year. Most patients' conditions were managed conservatively (68.5%). At follow-up, 17 patients (31.5%) had severe visual impairment (<6/60 Snellen equivalent) in their worse eye, and 16.7% had bilateral moderate/severe visual impairment., Conclusions: Contrary to some previous reports, our results show that OPGs in patients with NF1 often present in older children and may progress some time after diagnosis. Given the potential for serious visual consequences, these findings indicate a need for regular ophthalmological monitoring of this population for a long duration.

Aims: To determine the outcome of children with neuromuscular disease (NMD) following admission to a tertiary referral paediatric intensive care (PICU)., Methods: All children with chronic NMD whose first PICU admission was between July 1986 and June 2001 were followed up from their first PICU admission to time of study. The outcomes recorded were death in or outside of PICU, duration of PICU admission, artificial ventilation during admission and following discharge from PICU, and readmission to PICU., Results: Over 15 years, 28 children were admitted on 69 occasions. Sixteen (57%) children had more than one admission. The median duration of PICU admission was 4 days (range 0.5-42). Twenty three per cent of unplanned admissions resulted in the commencement of respiratory support that was continued after discharge from the PICU. Severity of functional impairment was not associated with longer duration of stay or higher PRISM scores. Ten children (36%) died, with four (14%) deaths in the PICU. A higher proportion of children with severe limitation of function were among children that died compared to survivors., Conclusion: Most children with NMD admitted to the PICU recover and are discharged without the need for prolonged invasive ventilation. However, in this group of children, the use of non-invasive home based ventilation is common and they are likely to require further PICU admission.

There is increasing evidence for strong genetic influences on athletic performance and for an evolutionary "trade-off" between performance traits for speed and endurance activities. We have recently demonstrated that the skeletal-muscle actin-binding protein alpha-actinin-3 is absent in 18% of healthy white individuals because of homozygosity for a common stop-codon polymorphism in the ACTN3 gene, R577X. alpha-Actinin-3 is specifically expressed in fast-twitch myofibers responsible for generating force at high velocity. The absence of a disease phenotype secondary to alpha-actinin-3 deficiency is likely due to compensation by the homologous protein, alpha-actinin-2. However, the high degree of evolutionary conservation of ACTN3 suggests function(s) independent of ACTN2. Here, we demonstrate highly significant associations between ACTN3 genotype and athletic performance. Both male and female elite sprint athletes have significantly higher frequencies of the 577R allele than do controls. This suggests that the presence of alpha-actinin-3 has a beneficial effect on the function of skeletal muscle in generating forceful contractions at high velocity, and provides an evolutionary advantage because of increased sprint performance. There is also a genotype effect in female sprint and endurance athletes, with higher than expected numbers of 577RX heterozygotes among sprint athletes and lower than expected numbers among endurance athletes. The lack of a similar effect in males suggests that the ACTN3 genotype affects athletic performance differently in males and females. The differential effects in sprint and endurance athletes suggests that the R577X polymorphism may have been maintained in the human population by balancing natural selection.

The syntrophins and dystrobrevins are members of the dystrophin-associated protein complex, and are thought to function as modular adaptors for signalling proteins recruited to the sarcolemmal membrane. We have characterised the expression of the syntrophins (alpha-, beta1-, and beta2-) and alpha-dystrobrevin by immunohistochemistry in normal human muscle and in biopsies from 162 patients with myopathies of unknown aetiology (with normal staining for dystrophin and other dystrophin-associated proteins). Unlike mice, beta2-syntrophin is expressed at the sarcolemma in post-natal human skeletal muscle. Deficiency of alpha-dystrobrevin +/- beta2-syntrophin was present in 16/162 (10%) patients, compared to age-matched controls. All patients presented with congenital-onset hypotonia and weakness, although there was variability in clinical severity. Two major clinical patterns emerged: patients with deficiency of beta2-syntrophin and alpha-dystrobrevin presented with severe congenital weakness and died in the first year of life, and two patients with deficiency of alpha-dystrobrevin had congenital muscular dystrophy with complete external ophthalmoplegia. We have sequenced the coding regions of alpha-dystrobrevin and beta2-syntrophin in these patients, and identified a new isoform of dystrobrevin, but have not identified any mutations. This suggests that disease causing mutations occur outside the coding region of these genes, in gene(s) encoding other components of the syntrophin-dystrobrevin subcomplex, or in gene(s) responsible for their post-translational modification and normal localisation.

Exposure to microwave radiation enhances the aggregation of bovine serum albumin in vitro in a time- and temperature-dependent manner. Microwave radiation also promotes amyloid fibril formation by bovine insulin at 60 degrees C. These alterations in protein conformation are not accompanied by measurable temperature changes, consistent with estimates from field modelling of the specific absorbed radiation (15-20 mW kg(-1)). Limited denaturation of cellular proteins could explain our previous observation that modest heat-shock responses are induced by microwave exposure in Caenorhabditis elegans. We also show that heat-shock responses both to heat and microwaves are suppressed after RNA interference ablating heat-shock factor function.

Background: Cognitive impairment is the most common complication of neurofibromatosis type 1 (NF1) in childhood. Current research suggests a strong relationship between cognitive deficits and brain T2-hyperintensities. The majority of these lesions disappear as the child ages. Cross-sectional data suggest that there also are improvements in intellect., Objective: To determine the natural history of cognitive functioning and MRI T2-hyperintensities from childhood into adulthood, and whether changes in MRI T2-hyperintensities over time are predictive of changes in cognitive functioning., Methods: The authors conducted a prospective longitudinal study of a cohort of 32 patients with NF1 and 11 unaffected sibling controls. All patients underwent neuropsychological assessments and 27 children underwent MRI examinations. The patients were then reassessed after an 8-year period., Results: and, Conclusions: There was no improvement in cognitive ability as the children with NF1 developed into adulthood compared with controls. Despite significant decreases in the number, size, and intensity of the T2-hyperintensities over the 8-year period, these changes were not associated with changes in cognitive ability. T2-hyperintensities in the cortex or subcortical or deep white matter are more frequent with age and these lesions are likely to have a different pathology than basal ganglia lesions. The best predictor of cognitive dysfunction in adulthood was the presence of T2-hyperintensities in childhood, rather than current lesion status. There is a limited time window (<18 years) in which the presence of T2-hyperintensities can be used as biologic markers of cognitive dysfunction.

Objectives: Previous research among American Indians of the strong heart family study (SHFS) has demonstrated significant heritabilities for CVD risk factors and implicated diabetes as an important predictor of several of the phenotypes. Moreover, we recently demonstrated that genetic effects on CVD risk factors differed in diabetic and nondiabetic individuals. In this paper, we investigated whether a significant genetic influence on diabetes status could be identified, and whether there is evidence for joint action of genes on diabetes status and related CVD risk factors., Methods and Results: Approximately 950 men and women, age 18 or older, in 32 extended families, were examined between 1997 and 1999. We estimated the effects of genes and environmental covariates on diabetes status using a threshold model and a maximum likelihood variance component approach. Diabetes status exhibited a residual heritability of 22% (h2=0.22). We also estimated the genetic and environmental correlations between diabetes susceptibility and eight risk factors for CVD. All eight CVD risk factors displayed significant genetic correlations with diabetes status (BMI (rhoG=0.55), fibrinogen (rhoG=0.40), HDL-C (rhoG=-0.37), ln triglycerides (rhoG=0.65), FAT (rhoG=0.38 ), PAI-1 (rhoG=0.67), SBP (rhoG=0.57), and WHR (rhoG=0.58)). Three of eight traits (HDL-C (rhoE=-0.32), ln triglycerides (rhoE=0.33), and fibrinogen (rhoE=0.20)) displayed significant environmental correlations with diabetes status., Conclusions: These findings suggest that in the context of a high prevalence of diabetes, still unidentified diabetes genes may play an important role in influencing variation in CVD risk factors.

Methods: We examined monocyte prostaglandin synthase 2 (PGS2/COX2) expression in individuals at risk for or with type 1 diabetes including: (i) 58 established type 1 and 2 diabetic patients; (ii) 34 autoantibody positive (AA+) children and adults; (iii) 164 infants and young children with insulin-dependent diabetes mellitus (IDDM) susceptibility human leukocyte antigen (HLA) alleles; and (iv) 37 healthy control individuals, over a 5-yr period., Results: Established type 1 diabetic patients (1 month to 30+ yr post-disease onset) had significantly higher PGS2 expression than healthy controls; by contrast, insulin-treated type 2 diabetic patients had significantly lower PGS2 expression than healthy controls. Longitudinal studies of AA+ subjects at risk for type 1 diabetes indicated that 73% (11/15) of individuals who developed this disease during the study period expressed high levels of PGS2 prior to or after onset. We also found high level PGS2 expression in genetically at-risk infants and young children that correlated with having a first-degree relative with type 1 diabetes, but not with age, gender, or HLA genotype. In this population, high level PGS2 expression coincided with or preceded autoantibody detection in 30% (3/10) of subjects., Conclusions: These findings suggest that high level monocyte PGS2 expression, although subject to fluctuation, is present in at-risk subjects at an early age and is maintained during progression to and after type 1 diabetes onset.

Purpose: To assess accuracy of mothers' understanding of their newborns' genetic risk for type 1 diabetes and to identify predictors of the comprehension and retention of genetic information., Methods: Mothers of 435 newborns genetically screened at birth were informed of the infant's risk for type 1 diabetes using a standard script that provided both categorical and numerical risk information. The mothers' comprehension and retention of this information were assessed by structured interview on two occasions, approximately 3.6 weeks and approximately 3.9 months postnotification., Results: At the initial interview, 73.1% of mothers gave a correct estimate of their child's genetic risk, 3.2% overestimated risk, 13.3% underestimated risk, and 10.3% could not recall risk at all. At the follow-up interview, fewer mothers (61.9%) correctly estimated their child's risk and more mothers (24.4%) underestimated their child's risk. Maternal accuracy was associated with maternal education, ethnic minority status, infant risk status, maternal ability to spontaneously recall both categorical and numerical risk estimates, and length of time since risk notification. Underestimation of risk was associated with maternal education, family history of diabetes, time since risk notification, and maternal anxiety about the baby's risk., Conclusion: The accuracy of mothers' recall of infant risk declines over time, with an increasing number of mothers underestimating the infant's risk. Effective risk communication strategies need to be developed and incorporated into genetic screening programs.

Objective: To report pathologic findings in 124 Australian and North American cases of primary nemaline myopathy., Methods: Results of 164 muscle biopsies from 124 Australian and North American patients with primary nemaline myopathy were reviewed, including biopsies from 19 patients with nemaline myopathy due to alpha-actin (ACTA1) mutations and three with mutations in alpha-tropomyosin(SLOW) (TPM3). For each biopsy rod number per fiber, percentage of fibers with rods, fiber-type distribution of rods, and presence or absence of intranuclear rods were documented., Results: Rods were present in all skeletal muscles and diagnosis was possible at all ages. Most biopsies contained nemaline bodies in more than 50% of fibers, although rods were seen only on electron microscopy in 10 patients. Rod numbers and localization correlated poorly with clinical severity. Frequent findings included internal nuclei and increased fiber size variation, type 1 fiber predominance and atrophy, and altered expression of fiber type specific proteins. Marked sarcomeric disruption, increased glycogen deposition, and intranuclear rods were associated with more severe clinical phenotypes. Serial biopsies showed progressive fiber size variation and increasing numbers of rods with time. Pathologic findings varied widely in families with multiple affected members., Conclusions: Very numerous nemaline bodies, glycogen accumulation, and marked sarcomeric disruption were common in nemaline myopathy associated with mutations in skeletal alpha-actin. Nemaline myopathy due to mutations in alpha-tropomyosin(SLOW) was characterized by preferential rod formation in, and atrophy of, type 1 fibers. Light microscopic features of nemaline myopathy correlate poorly with disease course. Electron microscopy may correlate better with disease severity and genotype.

The congenital myopathies are a group of disorders characterised by the predominance of specific histological features observed in biopsied muscle. Central core disease and nemaline myopathy are examples of congenital myopathies that have specific histological characteristics but significantly overlapping clinical pictures. Central core disease is an autosomal dominant disorder with variable penetrance which has been linked principally to the gene for the skeletal muscle calcium release channel (RYR1). Two recent reports have identified the 3' transmembrane domain of this gene as a common site for mutations. Two other studies have reported single families that have features of both central core disease and nemaline myopathy (core/rod disease) caused by mutations in RYR1. Screening of the 3' region (exons 93-105) of the RYR1 gene for mutations in 27 apparently unrelated patients with either central core disease or core/rod disease by single strand conformation polymorphism analysis and DNA sequencing identified three described and nine novel mutations in 15 patients.

Children with neurofibromatosis 1 (NF1) often develop low-grade gliomas, but brain tumors are infrequently encountered in adults with NF1. The authors present evidence from two clinical series, one including patients known to have NF1 and another focusing on adults with new onset brain tumors, that suggests an association between NF1 and symptomatic gliomas in older individuals. They also summarize the clinical data on 17 adolescents or adults with NF1 and symptomatic gliomas. The findings suggest that individuals with NF1 are at increased risk of developing gliomas throughout their lives.

Neurofibromatosis 1 is an autosomal dominant, multisystem disorder with myriad clinical manifestations. Between 1991 and 1998, 495 adults and children were diagnosed with neurofibromatosis 1 at a specialized neurogenetics clinic in Sydney, Australia. This review establishes the prevalence of the clinical manifestations of neurofibromatosis 1 in these patients and provides guidelines for assessment and management. In addition, we review in detail patients who had unusual presentations and who represent important "exceptions to the rules" of clinical practice.

Cognitive deficits and academic learning difficulties are the most common neurologic "complication" of neurofibromatosis 1 in childhood and can be responsible for significant lifetime morbidity. There is a slight increase in the frequency of mental retardation (Wechsler Full-Scale IQ < 70) in children with neurofibromatosis 1, but the mean Full-Scale IQ for the patient group is within 1 SD of the population mean. Academic difficulties are common, as are specific deficits in visuospatial ability, executive function, expressive and receptive language, and attentional skills. Behavioral and psychosocial problems have a major impact on quality of life, although there are few objective studies in this area Current research is focusing on the pathogenesis of the disorder. Clinical studies have identified possible radiologic and pathologic markers for cognitive deficits in neurofibromatosis 1, which can now be explored in animal models.

An important step in the diagnostic evaluation of a patient with recessive limb-girdle muscular dystrophy is the immunohistochemical analysis of the components of the sarcoglycan complex in a muscle biopsy specimen. Even though a primary mutation in any of the four sarcoglycan genes (alpha-, beta-,gamma-, delta-sarcoglycan) may cause secondary deficiencies in all the other sarcoglycan proteins, more specific immunohistochemical patterns have emerged with the potential to guide and abbreviate the necessary molecular genetic investigations. In gamma-sarcoglycan mutations, the pattern consists of absent or prominently reduced gamma-sarcoglycan immunoreactivity in combination with reduced but detectable immunoreactivity for the other components, with preservation of delta-sarcoglycan. In five consecutive patients, this pattern was able to predict primary gamma-sarcoglycan mutations. Five different mutations were found, including a recurrent novel splice mutation, a large deletion of the entire gene and a novel missense mutation (Leu90Ser). The mutation Cys283Tyr, previously restricted to Gypsy populations was found in compound heterozygosity with del521T, common in north Africa. The variety of known and novel mutations found indicates that the immunohistochemical profile of gamma-sarcoglycan mutations is not restricted to a particular mutation or type of mutation, but rather is a general reflection of the effect of gamma-sarcoglycan mutations on the composition of the sarcoglycan complex. Complete immunohistochemical analysis with all available sarcoglycan antibodies, therefore, is a useful tool to guide the molecular genetic investigations that are necessary to arrive at the correct genetic diagnosis in a given case.

The authors report a case of congenital muscular dystrophy with mild nonprogressive muscle weakness, white matter hypodensity, and absence of the laminin alpha2 chain in muscle fibers with two antibodies, but not with four others. They identified mutations in LAMA2, which explain the partial laminin alpha2 deficiency. Analysis of this case and two others allows us to refine the epitopes of two of the commercial antibodies, and illustrate the importance of using antibodies directed against different domains of the protein.