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Background: LKB1/STK11 germline mutations cause Peutz-Jeghers syndrome (PJS). The existence of a second PJS locus is controversial, the evidence in its favour being families unlinked to LKB1 and the low frequency of LKB1 mutations found using conventional methods in several studies. Exonic and whole gene deletion or duplication events cannot be detected by routine mutation screening methods. Objective: To seek evidence for LKB1 germline deletions or duplications by screening patients meeting clinical criteria for PJS but without detected mutations on conventional screening. Methods: From an original cohort of 76 patients, 48 were found to have a germline mutation by direct sequencing; the remaining 28 were examined using multiplex ligation dependent probe amplification (MLPA) analysis to detect LKB1 copy number changes. Results: Deletions were found in 11 of the 28 patients (39%)—that is, 14% of all PJS patients (11/76). Five patients had whole gene deletions, two had the promoter and exon 1 deleted, and in one patient exon 8 was deleted. Other deletions events involved: loss of exons 2–10; deletion of the promoter and exons 1–3; and loss of part of the promoter. No duplications were detected. Nine samples with deletions were sequenced at reported single nucleotide polymorphisms to exclude heterozygosity; homozygosity was found in all cases. No MLPA copy number changes were detected in 22 healthy individuals. Conclusions: These results lessen the possibility of a second PJS locus, as the detection rate of germline mutations in PJS patients was about 80% (59/76). It is suggested that MLPA, or a suitable alternative, should be used for routine genetic testing of PJS patients in clinical practice.

Systemic lupus erythematosus (SLE) is an autoimmune disease with diverse and variable clinical manifestations and unknown aetiology. Epidemiological and animal studies indicate that environmental and genetic factors are involved in the development of the disease. Several candidate gene loci (including the human leucocyte antigen ( HLA ) region, Fcγ receptors, and complement components) have been implicated through association studies, and multiple susceptibility loci have been detected in inbred mouse models of SLE.1,2 Until now, six groups have published genomewide scans with SLE as a phenotype in different ethnic groups.3–8 Recently, linkage to chromosome 2q37 (logarithm of odds (LOD) 4.24) in a Swedish population resulted in the identification of a new susceptibility gene PDCD1 in a large multinational study by Prokunina et al .8,9 The SLE associated allele of this immunoreceptor gene alters a binding site for the runt related transcription factor 1 ( RUNX1 ), which is found in an intronic enhancer. Stratification of pedigrees based on clinical manifestations has been used in recent studies that involved genomewide scans.10–16 The aim was to achieve genetically and clinically homogeneous sets of families and to increase the power to detect susceptibility genes for different subphenotypes of SLE. Altogether, 17 regions have been linked significantly to SLE with model based and non-parametric approaches; 11 of these in stratified studies. In addition, several other regions with suggestive linkage have been identified, but only some of those loci have been implicated in more than one study.6,18 The data suggest that multiple genes are involved in conferring susceptibility to SLE. In our study, we conducted a nationwide and genomewide scan for SLE susceptibility loci in Finnish families multiply affected by SLE. The extensive hospital registration system in Finland allowed us to identify and recruit approximately 85% of all patients with …

Retinitis pigmentosa (RP) is a progressive retinal degeneration that affects about 1 in 4000 of the population.1 Approximately 15–30% of patients with RP have X linked retinitis pigmentosa (XLRP), which is the most severe form of RP consistently manifesting early in life.2,3 Night blindness is usually present in early childhood with loss of peripheral visual fields and ultimately central vision, resulting in registered blindness by the end of the third decade. Female carriers display a broad spectrum of fundus appearances ranging from normal to extensive retinal degeneration.4–6 XLRP is genetically heterogeneous with two major loci, RP2 (Xp11.23) and RP3 (Xp21.1). Both disease genes have now been identified (respectively RP2 7 and RPGR 8–10) with RP2 mutations causing disease in approximately 15% of XLRP families,11,12 while RPGR mutations are reportedly more common, accounting for up to 75% of XLRP.10 Two other rare loci for XLRP have also been described on Xp22 and Xq26–27.13,141 Hong et al 15 described the phenotype and pathology of an RPGR knockout mouse model. They showed the subcellular localisation of RPGR to the photoreceptor connecting cilia, and in the absence of RPGR partial mislocalisation of essential outer segment proteins. These data suggest a putative role for RPGR in the retina, controlling movement of essential proteins from the inner to the outer segment of photoreceptors via the connecting cilia. Several groups have recently identified a retina specific RPGR interacting protein (RPGRIP1).16–18 This protein also localises to the photoreceptor connecting cilium and is thought to be a structural component of the ciliary axoneme.18 Subsequent mutation screening in patients suffering from retinal diseases has identified mutations in RPGRIP1 as a cause of Leber congenital amaurosis.19,20 In this report, we present the phenotype of …

It is widely accepted that curation of variation in genes is best performed by experts in those genes and their variation. However, obtaining funding for such variation is difficult even though up-to-date lists of variations in genes are essential for optimum delivery of genetic healthcare and for medical research. This study was undertaken to gather information on gene-specific databases (locus-specific databases) in an effort to understand their functioning, funding and needs. A questionnaire was sent to 125 curators and we received 47 responses. Individuals performed curation of up to 69 genes. The time curators spent curating was extremely variable. This ranged from 0 h per week up to 5 curators spending over 4 h per week. The funding required ranged from US$600 to US$45000 per year. Most databases were stimulated by the Human Genome Organization-Mutation Database Initiative and used their guidelines. Many databases reported unpublished mutations, with all but one respondent reporting errors in the literature. Of the 13 who reported hit rates, 9 reported over 52 000 hits per year. On the basis of this, five recommendations were made to improve the curation of variation information, particularly that of mutations causing single-gene disorder: 1. A curator for each gene, who is an expert in it, should be identified or nominated. 2. Curation at a minimum of 2 h per week at US$2000 per gene per year should be encouraged. 3. Guidelines and custom software use should be encouraged to facilitate easy setup and curation. 4. Hits per week on the website should be recorded to allow the importance of the site to be illustrated for grant-giving purposes. 5. Published protocols should be followed in the establishment of locus-specific databases.

Oxidative stress has been recently suggested to play a part in the development of osteoporosis. Catalase is a major antioxidant enzyme that detoxifies hydrogen peroxide by converting it into water and oxygen, thereby preventing cellular injury by oxidative stress.To examine the associations between the catalase gene (CAT) polymorphisms and bone mineral density (BMD) and bone turnover markers in postmenopausal Korean women.All exons, their boundaries and the promoter region (approximately 1.5 kb) were directly sequenced in 24 individuals. Among 18 variants identified by a direct sequence method, four polymorphisms were selected and genotyped in all study participants (n = 560). BMD at the lumbar spine and proximal femur was measured using dual-energy x ray absorptiometry. Serum osteocalcin concentrations and bone-specific alkaline phosphatase activity were determined by an immunoradiometric assay and an immunoassay, respectively.The mean (standard deviation) age of the participants was 59.4 (7.2) years. Multivariate analysis showed an association of the +22348C--T polymorphism with BMD at the lumbar spine (p = 0.01 in the dominant model) and at femur neck (p = 0.05 in the dominant model), and with serum osteocalcin level (p = 0.008 in the dominant model). Haplotype analyses showed that HT4 (-20T, +144C, +22348T, +33078A) was significantly associated with higher BMD at various sites (p0.001-0.03) and with lower serum osteocalcin levels (p = 0.01 in the codominant model).These findings indicate that the +22348C--T polymorphism and HT4 of CAT may be useful genetic markers for bone metabolism.

OBJECTIVE: To describe the clinical features of and genetic locus associated with autosomal-dominant macular dystrophy (MCDR5) in a large Greek family. METHODS: 26 members of a single family underwent clinical examinations and venepuncture. A genomewide linkage scan using 400 microsatellite markers distributed with an average spacing of 10 cM throughout the human genome. RESULTS: 14 members of the study family exhibited clinical features of the disease including decreased central vision and macular abnormalities in the posterior pole of the retina. Analysis of loci known to be associated with macular dystrophy did not show positive linkage. A genomewide linkage scan showed linkage to chromosome 19q, with a two-point maximum LOD score of 5.809 at theta = 0 between the disease and marker locus D19S412. On the basis of recombination events, the disease interval was localised between markers D19S420 and D19S540 on chromosome 19q, at a span of about 3.8 cM, in an area known to contain 120 known genes/transcripts. Eleven of these genes/transcripts were sequenced, and no disease-causing mutation was identified. CONCLUSIONS: This study describes a new locus on 19q associated with autosomal-dominant macular dystrophy, designated as MCDR5. Additional study of other family members will be necessary to further narrow the interval and identify the responsible gene. The study of MCDR5 will aid in elucidation of the underlying pathogenic mechanisms for this and other macular diseases, including age-related macular degeneration. J Med Genet

Background: Despite advances in the characterisation of mutations in the MECP2 -coding region, a small proportion of classic RTT cases remain without recognisable mutations. Objective and methods: To identify previously unknown mutations, a quantitative assay was established, providing estimates of MECP2\_e1 and MECP2\_e2 expression levels in peripheral blood. A systematic analysis of an Israeli cohort of 82 patients with classic and atypical RTT is presented, including sequence analysis of the MECP2 -coding region, MLPA, XCI and quantitative expression assays. Results and conclusion: A novel mis-sense mutation at ca 453C→T (pD151E), resulting in a change of a conserved residue at the methyl-binding domain, and a rare GT deletion of intron 1 donor splice site are reported. It is shown that various MECP2 mutations had distinct effects on MECP2 expression levels in peripheral blood. The most significant (p

Background: A single nucleotide polymorphism (SNP) in the coding region of the prion protein gene ( PRNP ) at codon 129 has been repeatedly shown to be an associated factor to sporadic Creutzfeldt-Jakob disease (sCJD), but additional major predisposing DNA variants for sCJD are still unknown. Several previous studies focused on the characterisation of polymorphisms in PRNP and the prion-like doppel gene ( PRND ), generating contradictory results on relatively small sample sets. Thus, extensive studies are required for validation of the polymorphisms in PRNP and PRND . Methods: We evaluated a set of nine SNPs of PRNP and one SNP of PRND in 593 German sCJD patients and 748 German healthy controls. Genotyping was performed using MALDI-TOF mass spectrometry. Results: In addition to PRNP 129, we detected a significant association between sCJD and allele frequencies of six further PRNP SNPs. No significant association of PRND T174M with sCJD was shown. We observed strong linkage disequilibrium within eight adjacent PRNP SNPs, including PRNP 129. However, the association of sCJD with PRNP 1368 and PRNP 34296 appeared to be independent on the genotype of PRNP 129. We additionally identified the most common haplotypes of PRNP to be over-represented or under-represented in our cohort of patients with sCJD. Conclusion: Our study evaluated previous findings of the association of SNPs in the PRNP and PRND genes in the largest cohorts for association study in sCJD to date, and extends previous findings by defining for the first time the haplotypes associated with sCJD in a large population of the German CJD surveillance study.

Inducible heme oxygenase (HO-1) acts against oxidants that are thought to play a major role in the pathogenesis of chronic obstructive pulmonary disease (COPD), characterised by impaired lung function. A (GT)(n) repeat polymorphism in the HO-1 gene promoter can modulate the gene transcription in response to oxidative stress. We hypothesised that this polymorphism could be associated with the level of lung function and decline in subjects exposed to oxidative aggression (smokers). We genotyped 749 French subjects (20-44 years, 50% men, 40% never smokers) examined in both 1992 and 2000 as part of the ECRHS. Lung function was assessed by forced expiratory volume in 1 second (FEV1) and FEV1/forced ventilatory capacity (FVC) ratio. We compared long (L) allele carriers ((GT)(n) > or =33 repeats for one or two alleles) to non-carriers. Cross sectionally, in 2000, L allele carriers showed lower FEV1/FVC than non-carriers. During the 8 year period, the mean annual FEV1 and FEV1/FVC declines were -30.9 (31.1) ml/year and -1.8 (6.1) U/year, respectively. FEV1/FVC decline was steeper in L allele carriers than in non-carriers (-2.6 (5.5) v -1.5 (6.4), p = 0.07). There was a strong interaction between the L allele and smoking. In 2000, the L allele was associated with lower FEV(1) and FEV(1)/FVC in heavy smokers (> or =20 cigarettes/day) only (p for interaction = 0.07 and 0.002 respectively). Baseline heavy smokers carrying the L allele showed the steepest FEV1 decline (-62.0 (29.5 ml/year) and the steepest FEV1/FVC decline (-8.8 (5.4 U/year) (p for interaction = 0.009 and 0.0006). These results suggest that a long (L) HO-1 gene promoter in heavy smokers is associated with susceptibility to develop airway obstruction.

Background: We report here the genetic characterisation of a large five generation Chinese family with the phenotypic features of auditory neuropathy and progressive peripheral sensory neuropathy, and the genetic feature of X linked recessive inheritance. Disease onset was at adolescence (at an average age of 13 years for six affected subjects). The degree of hearing impairment varied from mild to severe, with decreased otoacoustic emissions; auditory brainstem responses were lacking from onset. Methods: Two-point and multipoint model based linkage analysis using the MILNK and LINKMAP programs of the FASTLINK software package produced maximum two-point and multipoint LOD scores of 2.41 and 2.41, respectively. Results: These findings define a novel X linked auditory neuropathy locus/region ( AUNX1 , Xq23–q27.3). This region is 42.09 cM long and contains a 28.07 Mb region with flanking markers DXS1220 and DXS8084, according to the Rutgers Combined Linkage-Physical Map, build 35. However, mutation screen of the candidate gene SLC6A14 within the region did not identify the causative genetic determinant for this large Chinese family.

Mutations in the p63 gene (TP63) underlie several monogenic malformation syndromes manifesting cleft lip with or without cleft palate (CL/P). We investigated whether p63 mutations also result in non-syndromic CL/P. Specifically, we performed mutation analysis of the 16 exons of the p63 gene for 100 Thai patients with non-syndromic CL/P. In total, 21 variant sites were identified. All were single nucleotide changes, with six in coding regions, including three novel non-synonymous changes: S90L, R313G, and D564H. The R313G was concluded to be pathogenic on the basis of its amino acid change, evolutionary conservation, its occurrence in a functionally important domain, its predicted damaging function, its de novo occurrence, and its absence in 500 control individuals. Our data strongly suggest, for the first time, a causative role of a heterozygous mutation in the p63 gene in non-syndromic CL/P, highlighting the wide phenotypic spectrum of p63 gene mutations.

Background: Delayed puberty is common among individuals with cystic fibrosis (CF) and is usually attributed to chronic disease and/or poor nutrition. However, it has recently been recognised that pubertal delay can occur even in the setting of good nutritional and clinical status. This finding, along with evidence that Cftr is expressed in rat brain, human hypothalamus, and a gonadotropin releasing hormone secreting cell line, raises the possibility that some of the pubertal delay in CF could stem directly from alterations in Cftr function that affect the hypothalamic-pituitary-gonadal axis. Methods: To examine this hypothesis, we investigated pubertal timing (as assessed by vaginal opening (VO)) in a mouse model of CF ( Cftr tm1Unc ) engineered to produce a truncated Cftr mRNA and referred to as S489X. Homozygous knockout, heterozygote, and wild type (WT) female mice were examined. Results: As expected, the S489X − /S489X − knockout mice, which have chronic inflammation and gastrointestinal disease, grew more slowly and had later onset of puberty than WT animals. We anticipated that the S489X − /S489X + heterozygotes, which have no clinical CF phenotype, might display an intermediate timing of puberty. Surprisingly, however, these mice had earlier VO than WT. These findings were confirmed in a second, independent model of CF engineered to generate the ΔF508 mutation in mice. Again, the homozygotes displayed later pubertal timing, while the heterozygotes displayed earlier VO than the WT animals. Conclusions: These data provide further evidence that Cftr can directly modulate the reproductive endocrine axis and raise the possibility that heterozygate mutation carriers may have a reproductive advantage.

Background: In a search for mutations of m-crystallin (CRYM), a taxion specific crystalline which is also known as an NADP regulated thyroid hormone binding protein, two mutations were found at the C-terminus in patients with nonsyndromic deafness. Objective: To investigate the mechanism of hearing loss caused by CRYM mutations Methods: T3 binding activity of mutant m-crystallin was compared with that of wild-type m-crystallin, because mcrystallin is known to be identical to T3 binding protein. To explore the sites within the cochlea where m-crystallin is functioning, its localisation in the mouse cochlea was investigated immunocytochemically using a specific antibody. Results: One mutant was shown to have no binding capacity for T3, indicating that CRYM mutations cause auditory dysfunction through thyroid hormone binding properties. Immunocytochemical results indicated that m-crystallin was distributed within type II fibrocytes of the lateral wall, which are known to contain Na,K-ATPase. Conclusions: CRYM mutations may cause auditory dysfunction through thyroid hormone binding effects on the fibrocytes of the cochlea. m-Crystallin may be involved in the potassium ion recycling system together with Na,KATPase. Future animal experiments will be necessary to confirm a causal relation between Na,K-ATPase, T3, and deafness.

Molecular definition at the BAC level of an 8p dicentric chromosome and an 8p deleted chromosome is reported in a patient with two different cell lines. The dicentric, which differed from that generating the recurrent inv dup del(8p) for the location of its break point, originated during the paternal meiosis on the background of the classical 8p23.1 inversion polymorphism. The breakage of this dicentric gave rise to the 8p deleted chromosome which, as a result of the inversion, had two non-contiguous deletions. These findings confirm previous data on 1p distal deletions, showing that at least some of the deletions stem from the breakage of dicentric chromosomes. They suggest that non-contiguous deletions may be frequent among distal deletions. This type of rearrangement can easily be overlooked when two contiguous clones, one absent and the other present by FISH analysis, are taken as boundaries of the deletion break point; in this case only high resolution array-CGH will reveal their real frequency. The definition of such non-contiguous distal deletions is relevant for phenotype/karyotype correlations. There are historical examples of blunders caused by overlooking a second non-contiguous deletion. This paper shows how small scale structural variations, such as common polymorphic inversions, may cause complex rearrangements such as terminal deletions.

Hereditary mixed polyposis syndrome (HMPS) is characterised by colonic polyps of mixed histological types that are autosomal dominantly inherited and eventually lead to colorectal cancer (CRC). Study of the molecular basis of HMPS will enhance our knowledge of the genetic basis of the mixed polyposis-carcinoma sequence in both hereditary and sporadic CRC.We performed a genomewide linkage search on 15 members of a three-generation HMPS family using the GeneChip Human Mapping 10K Array and identified a 7 cM putative linkage interval on chromosome 10q23. Subsequently, 32 members from two HMPS families were typed with nine microsatellite markers spanning the region and the linkage was confirmed with a maximum multi-point logarithm of the odds (LOD) score of 4.6 (p0.001). The 10q23.1-10q23.31 haplotypes segregate with the disease in both families. We screened for mutations in four candidate genes within the linkage region and identified an 11 bp deletion in the bone morphogenesis protein receptor 1A (BMPR1A) gene in one family.Our results indicate that BMPR1A mutation accounts for HMPS. The data suggest that inactivating BMPR1A can initiate colorectal tumourigenesis via the mixed polyposis-carcinoma sequence.

Background: Asperger syndrome is characterised by abnormalities in social interaction as well as repetitive and stereotyped behaviours and interests. The trait is thought to display complex inheritance, but in a subset of families the inheritance resembles the autosomal dominant model. Linkage to 3p14–24 has recently been reported in Asperger syndrome in Finnish families with a maximum multipoint NPL all of 3.32 at D3S2432. Methods: We have replicated linkage findings to 3p21–24 in 12 new extended Asperger syndrome families. Linkage analyses were performed separately for the 12 new families, and linkage and association analyses were also performed jointly with data from the original genome-wide screen. Results: Best two point and multipoint logarithm of the odds (LOD) scores in analyses of both data sets were obtained at D3S2432 (NPL all = 3.83) with both subsets of families contributing to linkage. Association analysis of the combined data set produced a trend towards association with D3S2432 and D3S1619. Conclusions: This study further validates 3q21–24 as a candidate region for Asperger syndrome.

Background: The best known hereditary colorectal cancer syndromes, familial adenomatous polyposis (FAP) and hereditary non-polyposis colorectal cancer (HNPCC), constitute about 2% of all colorectal cancers, and there are at least as many non-FAP, non-HNPCC cases where the family history suggests a dominantly inherited colorectal cancer risk. Recently, a locus on chromosome 9q22.2–31.2 was identified by linkage analysis in sib pairs with colorectal cancer or adenoma. Methods: Linkage analysis for the suggested locus on chromosome 9 was carried out in an extended Swedish family. This family had previously been investigated but following the identification of adenomas in several previously unaffected family members, these subjects were now considered to be gene carriers. Results: In the present study, we found linkage of adenoma and colorectal cancer to chromosome 9q22.32–31.1 with a multipoint LOD score of 2.4. We were also able to define the region for this locus to 7.9 cM between the markers D9S280 and D9S277. Conclusions: Our result supports the presence of a susceptibility locus predisposing to adenoma and colorectal cancer in this chromosomal region.

Background: Desmosomes are cellular junctions important for intercellular adhesion and anchoring the intermediate filament (IF) cytoskeleton to the cell membrane. Desmoplakin (DSP) is the most abundant desmosomal protein with 2 isoforms produced by alternative splicing. Methods: We describe a patient with a recessively inherited arrhythmogenic dilated cardiomyopathy with left and right ventricular involvement, epidermolytic palmoplantar keratoderma, and woolly hair. The patient showed a severe heart phenotype with an early onset and rapid progression to heart failure at 4 years of age. Results: A homozygous nonsense mutation, R1267X, was found in exon 23 of the desmoplakin gene, which results in an isoform specific truncation of the larger DSPI isoform. The loss of most of the DSPI specific rod domain and C-terminal area was confirmed by Western blotting and immunofluorescence. We further showed that the truncated DSPI transcript is unstable, leading to a loss of DSPI. DSPI is reported to be an obligate constituent of desmosomes and the only isoform present in cardiac tissue. To address this, we reviewed the expression of DSP isoforms in the heart. Our data suggest that DSPI is the major cardiac isoform but we also show that specific compartments of the heart have detectable DSPII expression. Conclusions: This is the first description of a phenotype caused by a mutation affecting only one DSP isoform. Our findings emphasise the importance of desmoplakin and desmosomes in epidermal and cardiac function and additionally highlight the possibility that the different isoforms of desmoplakin may have distinct functional properties within the desmosome.

We report on a multigenerational family with isolated Hirschsprung's disease (HSCR). Five patients were affected by either short segment or long segment HSCR. The family consists of two main branches: one with four patients ( three siblings and one maternal uncle) and one with one patient. Analysis of the RET gene, the major gene involved in HSCR susceptibility, revealed neither linkage nor mutations. A genome wide linkage analysis was performed, revealing suggestive linkage to a region on 4q31-q32 with a maximum parametric multipoint LOD score of 2.7. Furthermore, non-parametric linkage (NPL) analysis of the genome wide scan data revealed a NPL score of 2.54 (p= 0.003) for the same region on chromosome 4q (D4S413-D4S3351). The minimum linkage interval spans a region of 11.7 cM (12.2 Mb). No genes within this chromosomal interval have previously been implicated in HSCR. Considering the low penetrance of disease in this family, the 4q locus may be necessary but not sufficient to cause HSCR in the absence of modifying loci elsewhere in the genome. Our results suggest the existence of a new susceptibility locus for HSCR at 4q31.3-q32.3.

Background: Allergic diseases such as asthma and rhinitis have closely related phenotypes and often occur with atopy. They show strong familial and intra-individual clustering, suggesting overlapping disease aetiology. Various loci and candidate genes have been suggested to underlie allergy. Many or all are still inconclusive. Following genome-wide scans on multiple phenotypes, we previously suggested that chromosome 3q13.12–q21.2 harbours an allergy locus. Objective: To identify candidate loci in the Danish population, two additional independent sets of sib-pair families were fine-scale mapped in candidate regions showing maximum likelihood scores (MLS) ⩾1.5 in the genome-wide scans. Results: Twenty eight microsatellite markers in a denser map on chromosome 3q were analysed in 236 allergy sib-pair families including 125 sib pairs with rhinitis. We report significant evidence for linkage to chromosome 3q13.31 for rhinitis (MLS 5.55, identity by descent (IBD) 63.9%) and atopy (increased specific immunoglobulin E) (MLS 3.71, IBD 61.7%). We obtained an MLS of 5.1 (IBD 67.3%) at 3q13.31 when sib pairs with both rhinitis and atopy were analysed. Conclusion: This study reports the first statistically significant evidence for a genetic susceptibility locus for rhinitis and to our knowledge shows the most significant evidence to date of linkage for any allergy phenotype.

BACKGROUND: Peutz-Jeghers syndrome (PJS) is caused by germline STK11 mutations and characterised by gastrointestinal polyposis. Although small bowel intussusception is a recognised complication of PJS, risk varies between patients.OBJECTIVE: To analyse the time to onset of intussusception in a large series of PJS probands.METHODS: STK11 mutation status was evaluated in 225 PJS probands and medical histories of the patients reviewed.RESULTS: 135 (60%) of the probands possessed a germline STK11 mutation; 109 (48%) probands had a history of intussusception at a median age of 15.0 years but with wide variability (range 3.7 to 45.4 years). Median time to onset of intussusception was not significantly different between those with identified mutations and those with no mutation detected, at 14.7 years and 16.4 years, respectively (log-rank test of difference, chi(2) = 0.58, with 1df; p = 0.45). Similarly no differences were observed between patient groups on the basis of the type or site of STK11 mutation.CONCLUSIONS: The risk of intussusception in PJS is not influenced by STK11 mutation status.

Background: Primary ciliary dyskinesia (PCD) is a genetic disorder caused by ciliary immotility/dysmotility due to ultrastructural defects of the cilia. Kartagener syndrome (KS), a subtype of PCD, is characterised by situs inversus accompanying the typical PCD symptoms of bronchiectasis and chronic sinusitis. In most cases, PCD is transmitted as an autosomal recessive trait, but its genetic basis is unclear due to extensive genetic heterogeneity. Methods: In a genome-wide search for PCD loci performed in 52 KS families and in 18 PCD families with no situs inversus present (CDO, ciliary dysfunction-only), the maximal pairwise LOD score of 3.36 with D15S205 in the KS families indicated linkage of a KS locus to the long arm of chromosome 15. In the follow-up study, 65 additional microsatellite markers encompassing D15S205 were analysed. Results: A maximal pairwise LOD score of 4.34 was observed with D15S154, further supporting linkage of the KS, but not the CDO, families to 15q24–25. Analysis of heterogeneity and haplotypes suggested linkage to this region in 60% of KS families. Conclusions: Reinforced by the results of multipoint linkage, our analyses indicate that a major KS locus is localised within a 3.5 cM region on 15q, between D15S973 and D15S1037.

Cohen syndrome (CS) is an autosomal recessive disorder with variability in the clinical manifestations, characterised by mental retardation, postnatal microcephaly, facial dysmorphism, pigmentary retinopathy, myopia, and intermittent neutropenia. Mutations in the gene COH1 have been found in an ethnically diverse series of patients. Brief clinical descriptions of 24 patients with CS are provided. The patients were from 16 families of different ethnic backgrounds and between 2.5 and 60 years of age at assessment. DNA samples from all patients were analysed for mutations in COH1 by direct sequencing. Splice site mutations were characterised using reverse transcriptase PCR analysis from total RNA samples. In this series, we detected 25 different COH1 mutations; 19 of these were novel, including 9 nonsense mutations, 8 frameshift mutations, 4 verified splice site mutations, 3 larger in frame deletions, and 1 missense mutation. We observed marked variability of developmental and growth parameters. The typical facial gestalt was seen in 23/24 patients. Early onset progressive myopia was present in all the patients older than 5 years. Widespread pigmentary retinopathy was found in 12/14 patients assessed over 5 years of age. We present evidence for extended allelic heterogeneity of CS, with the vast majority of mutations leading to premature termination codons in COH1. Our data confirm the broad clinical spectrum of CS with some patients lacking even the characteristic facial gestalt and pigmentary retinopathy at school age.

Background: Beckwith-Wiedemann syndrome (BWS) is an overgrowth disorder with increased risk of paediatric tumours. The aetiology involves epigenetic and genetic alterations affecting the 11p15 region, methylation of the differentially methylated DMR2 region being the most common defect, while less frequent aetiologies include mosaic paternal 11p uniparental disomy (11patUPD), maternally inherited mutations of the CDKN1C gene, and hypermethylation of DMR1. A few patients have cytogenetic abnormalities involving 11p15.5. Methods: Screening of 70 trios of BWS probands for 11p mosaic paternal UPD and for cryptic cytogenetic rearrangements using microsatellite segregation analysis identified a profile compatible with paternal 11p15 duplication in two patients. Results: Fluorescence in situ hybridisation analysis revealed in one case the unbalanced translocation der(21)t(11;21)(p15.4;q22.3) originated from missegregation of a cryptic paternal balanced translocation. The second patient, trisomic for D11S1318, carried a small de novo dup(11)(p15.5p15.5), resulting from unequal recombination at paternal meiosis I. The duplicated region involves only IC1 and spares IC2/LIT1, as shown by fluorescent in situ hybridisation (FISH) mapping of the proximal duplication breakpoint within the amino-terminal part of KvLQT1. Conclusions: An additional patient with Wolf-Hirschorn syndrome was shown by FISH studies to carry a der(4)t(4;11)(p16.3;p15.4), contributed by a balanced translocation father. Interestingly, refined breakpoint mapping on 11p and the critical regions on the partner 21q and 4p chromosomal regions suggested that both translocations affecting 11p15.4 are mediated by segmental duplications. These findings of chromosomal rearrangements affecting 11p15.5–15.4 provide a tool to further dissect the genomics of the BWS region and the pathogenesis of this imprinting disorder.

Multipoint linkage analysis in complex diseases requires the use of fast algorithms that can handle many markers and a large number of moderately sized pedigrees with unknown mode of inheritance. This need has led to the development of several competitive software programs. We recently completed a genomic screen of neural tube defects using GENEHUNTER-PLUS and the more recent ALLEGRO. The ALLEGRO software was found to offer expanded power for linkage studies, particularly for childhood onset diseases like neural tube defects, though the results must be treated with caution.

To report the frequency of single and multiple gene mutations in an Australian cohort of patients with hypertrophic cardiomyopathy (HCM).Genetic screening of seven HCM genes (beta-MHC, MyBP-C, cTnT, cTnI, ACTC, MYL2, and MYL3) was undertaken in 80 unrelated probands. Screening was by denaturing high performance liquid chromatography and direct DNA sequencing. Clinical data were collected on all patients and on genotyped family members.26 mutations were identified in 23 families (29%). Nineteen probands (24%) had single mutations (11 beta-MHC, 4 MyBP-C, 3 cTnI, 1 cTnT). Multiple gene mutations were identified in four probands (5%): one had a double mutation and the others had compound mutations. Six of 14 affected individuals from multiple mutation families (43%) experienced a sudden cardiac death event, compared with 10 of 55 affected members (18%) from single mutation families (p = 0.05). There was an increase in septal wall thickness in patients with compound mutations (mean (SD): 30.7 (3.1) v 24.4 (7.4) mm; p0.05).Multiple gene mutations occurring in HCM families may result in a more severe clinical phenotype because of a "double dose" effect. This highlights the importance of screening the entire panel of HCM genes even after a single mutation has been identified.

Background: Neonatal screening for metabolic diseases, involving samples stored on filter paper (Guthrie spots), provides a potential resource for genetic epidemiological studies. Objective: To develop a method to make these dried blood spots available for large scale genetic epidemiology. Methods: DNA from untraceable Guthrie spots was extracted using a saponin and chelex-100 based method and preamplified by improved primer preamplification. Analyses were done on 38 samples each of fresh, 10, and 25 year old Guthrie spots and the success rate determined for PCR amplification for five amplicon lengths. Results: The method was applicable even on 25 year old samples. The success rate was 100% for 100 bp amplicons and 80% for 396 bp amplicons. Ninety four Guthrie samples were genotyped, including carriers of two different PKU mutations; all carriers were found (six R158Q, four R252W), with no false positives. Finally, 2132 anonymous samples from the Swedish PKU registry were extracted and preamplified and the allele frequencies of APOe4, PPARγ Pro12Ala, and the CCR5 32 bp deletion determined. Local variations in allele frequencies suggested subpopulation structuring. There was a significant difference (p

Background: Most cases of Sotos syndrome are caused by intragenic NSD1 mutations or 5q35 microdeletions. It is uncertain whether allelic or genetic heterogeneity underlies the residual cases and it has been proposed that other mechanisms, such as 11p15 defects, might be responsible for Sotos cases without NSD1 mutations or 5q35 microdeletions. Objective: To develop a multiplex ligation dependent probe amplification (MLPA) assay to screen NSD1 for exonic deletions/duplications. Methods: Analysis was undertaken of 18 classic Sotos syndrome cases in which NSD1 mutations and 5q35 microdeletions were excluded. Long range polymerase chain reaction (PCR) was used to characterise the mechanism of generation of the partial NSD1 deletions. Results: Eight unique partial NSD1 deletions were identified: exons 1–2 (n = 4), exons 3–5, exons 9–13, exons 19–21, and exon 22. Using long range PCR six of the deletions were confirmed and the precise breakpoints in five cases characterised. This showed that three had arisen through Alu - Alu recombination and two from non-homologous end joining. Conclusions: MLPA is a robust, inexpensive, simple technique that reliably detects both 5q35 microdeletions and partial NSD1 deletions that together account for ∼15% of Sotos syndrome.

Background : Infection with human papillomavirus (HPV) is the main cause of cervical cancer and its precursor lesion, cervical intraepithelial neoplasia (CIN). Variability in host immunogenetic background is important in determining the overall cellular immune response to HPV infections.Objective : To determine whether the HLA-DQ or HLA-DR genes, or others in their vicinity, are associated with cervical cancer.Methods : Markers covering the entire HLA region were genotyped in a large sample of CIN and cervical cancer patients and in controls ( 311 CIN, 695 cervical cancer, 115 family controls, and 586 unrelated controls).Results : Two markers were associated with susceptibility to cervical neoplasia, G511525 and MICA. G511525, close to the region containing the HLA-DQ and HLA-DR genes, was most strongly associated, showing a decrease in frequency of allele 221 from 6.7% to 3.3% in patients with squamous cell cancer (SCC). An association was found for MICA ( allele 184) with SCC ( odds ratio ( OR) = 1.31 (95% confidence interval, 1.13 to 1.53); homozygotes, OR = 1.48 (1.06 to 2.06)). No associations were observed with adenocarcinoma or CIN.Conclusions : There is an association of the region containing the HLA-DQ and HLA-DR genes with the risk of developing squamous cell carcinoma. An increased risk was observed for carriers of allele 184 at the MICA locus, in particular for homozygotes, suggesting a recessive effect.

Cowden syndrome (OMIM No 158350) is a pleomorphic, autosomal dominant syndrome characterised by hamartomas in tissues derived from the endoderm, mesoderm, and ectoderm. It is caused by germline mutations in the PTEN gene and is allelic to the Bannayan–Riley–Ruvalcaba and Lhermitte–Duclos syndromes. The three syndromes are defined on clinical grounds but there is overlap in their definitions. The clinical features include trichilemmomas, verrucose lesions of the skin, macrocephaly, intellectual disability, cerebellar gangliocytoma, thyroid adenomas, fibroadenomas of the breast, and hamartomatous colonic polyps. Cutaneous haemangiomas are occasionally noted. Malignancies often arise in the affected tissues. Visceral arteriovenous malformations are a recognised component of the Bannayan–Riley–Ruvalcaba syndrome but have been reported rarely in Cowden syndrome. A family is described with a clinical diagnosis of Cowden syndrome, a familial frameshift mutation in the PTEN gene, and large visceral arteriovenous malformations. The association of these pleomorphic syndromes with arteriovenous malformations can be explained by the putative role of the PTEN gene in suppressing angiogenesis. Recognition of arteriovenous malformations as a clinical feature of Cowden syndrome has implications for the clinical management of patients with this disorder.

Boomerang dysplasia (BD) is a perinatal lethal osteochondrodysplasia, characterised by absence or underossification of the limb bones and vertebrae. The BD phenotype is similar to a group of disorders including atelosteogenesis I, atelosteogenesis III, and dominantly inherited Larsen syndrome that we have recently shown to be associated with mutations in FLNB, the gene encoding the actin binding cytoskeletal protein, filamin B. We report the identification of mutations in FLNB in two unrelated individuals with boomerang dysplasia. The resultant substitutions, L171R and S235P, lie within the calponin homology 2 region of the actin binding domain of filamin B and occur at sites that are evolutionarily well conserved. These findings expand the phenotypic spectrum resulting from mutations in FLNB and underline the central role this protein plays during skeletogenesis in humans.

Background: Gaucher disease is classified into neuronopathic and non-neuronopathic forms with wide phenotypic variation among patients sharing the same genotype. While homozygosity for the common L444P allele usually correlates with the neuronopathic forms, how a defined genotype leads to a phenotype remains unknown. Methods: The genetic and epigenetic factors causing phenotypic differences were approached by a clinical association study in 32 children homozygous for the point mutation L444P. Direct sequencing and Southern blots were utilised to establish the genotype and exclude recombinant alleles. Glucocerebrosidase activity was measured in lymphoblast and fibroblast cell lines. Results: Residual enzyme activity was highly variable and did not correlate with the observed clinical course. There was also a wide spectrum of phenotypes. Average age at diagnosis was 15 months, and slowed saccadic eye movements were the most prevalent finding. The most severe systemic complications and highest mortality occurred in splenectomised patients before the advent of enzyme replacement therapy (ERT). On ERT, as morbidity and mortality decreased, developmental and language deficits emerged as a major issue. Some trends related to ethnic background were observed. Conclusion: The wide clinical spectrum observed in the L444P homozygotes implicates the contribution of genetic modifiers in defining the phenotype in Gaucher disease.

BACKGROUND: The melanocortin-4-receptor gene (MC4R) is part of the melanocortinergic pathway that controls energy homeostasis. In a recent meta-analysis, the MC4R V103I (rs2229616) polymorphism was shown to be associated with body weight regulation. Although no functional differences between the isoleucine comprising receptor and the wild type receptor have been detected as yet, this meta-analysis of 14 case-control studies reported a mild negative association with obesity (odds ratio (OR) 0.69, p = 0.03). However, evidence in a large population based study in a homogeneous population and a significant estimate of the change in quantitative measures of obesity is still lacking. METHODS: We analysed the data of two surveys of a white population with the same high quality study protocol, giving a total of 7937 participants. RESULTS: By linear regression, we found a significant decrease of 0.52 body mass index (BMI) units (95% confidence interval (CI) -0.02 to -1.03, p = 0.043) for carriers of the heterozygote rs2229616G/A genotype, which was observed in 3.7% of the participants. Logistic regression yielded a significantly negative association of the MC4R variant with "above average weight" (BMI > or = median BMI) yielding an OR of 0.75 (95% CI 0.59 to 0.95 p = 0.017). We obtained similar results comparing obese (BMI > or =30 kg/m2, World Health Organization results for 1997) with non-obese (BMI < 30 kg/m2) participants. The results were found for both sexes and each survey separately, and did not depend on the modelling of age, sex, or survey effects. CONCLUSIONS: Our study confirms previous findings of a meta-analysis that the relatively infrequent G/A genotype of the V103I MC4R polymorphism is negatively associated with above average weight and obesity in population based original data of 7937 participants, and extends previous findings by showing for the first time a significantly lower BMI in individuals carrying the infrequent allele of this MC4R variant.

Noonan-like/multiple giant cell lesion syndrome (NL/MGCLS; OMIM 163955) is a rare condition1–3 with phenotypic overlap with Noonan’s syndrome (OMIM 163950) and cherubism (OMIM 118400) (table 1). View this table: Table 1 Comparison of the clinical characteristics of cherubism, Noonan’s syndrome, and Noonan-like/multiple giant cell lesion syndrome Recently, missense mutations in the PTPN11 gene on chromosome 12q24.1 have been identified as the cause of Noonan’s syndrome in 45% of familial and sporadic cases,4,5 indicating genetic heterogeneity within the syndrome. In the study by Tartaglia et al ,5 there was a family in which three members had features of Noonan’s syndrome; two of these had incidental mandibular giant cell lesions.3 All three members were found to have a PTPN11 mutation known to cosegregate with the Noonan phenotype. This mutation, an A→G transition at position 923 in exon 8, predicting an Asn308Ser substitution within the PTP domain, was identified in an unrelated kindred with classical Noonan’s syndrome. No other patients with NL/MGCLS had been evaluated for the PTPN11 mutation. Cherubism is caused by a missense mutation in the coding region of the SH3BP2 gene on chromosome 4p16.3.6 In the study by Ueki et al ,6 12 of 15 families showed point mutations in the SH3 binding protein, SH3BP2. All seven mutations identified were on exon 9 and affected three amino acids by substitution within a six amino acid sequence. A second locus or gene has not been identified. We present the phenotype of three sporadic cases of NS/MGCLS and the results of mutation analysis of the PTPN11 and SH3BP2 genes. The clinical features of the three patients are summarised in table 2. View this table: Table 2 Phenotype of three patients with Noonan-like/multiple giant cell lesion syndrome All patients were enrolled in the National Institutes of Health IRB approved protocols and written informed consent was …

Hutchinson–Gilford progeria syndrome (HGPS; OMIM 176670) is an extremely rare but devastating disorder that mimics premature aging.1–3 Affected children appear normal at birth but typically develop failure to thrive in the first two years. Other features include alopecia, micrognathia, loss of subcutaneous fat with prominent veins, abnormal dentition, sclerodermatous skin changes, and osteolysis of the clavicles and distal phalanges. The mean age of death is at age 13 years, most commonly due to atherosclerosis. HGPS is mainly sporadic in occurrence, but a genetic cause has now been implicated following the identification of de novo heterozygous mutations in the LMNA gene in the majority of HGPS patients.4,5 A single family showing autosomal recessive inheritance of homozygous LMNA mutations has also been reported.6 LMNA encodes lamins A and C, components of the nuclear lamina, a meshwork underlying the nuclear envelope that serves as a structural support and is also thought to contribute to chromatin organisation and the regulation of gene expression.7,8 Interestingly, mutations in LMNA have recently been associated with at least eight inherited disorders, known as laminopathies, with differential dystrophic effects on a variety of tissues including muscle, neurones, skin, bone, and adipose tissue (reviewed in Mounkes et al 9). However, the realisation that these disorders share common genetic defects has led to clinical re-evaluation, with emerging evidence of significant phenotypic overlap.10 Hence the laminopathies might reasonably be considered as a spectrum of related diseases. HGPS has phenotypic similarities to several other laminopathies, in particular the atypical Werner’s syndrome11 and mandibuloacral dysplasia (MAD; OMIM 248370 and 608612).12 These diseases are associated with lipodystrophy,3,13 which is the most prominent feature of another laminopathy, familial partial lipodystrophy of the Dunnigan variety (OMIM 151660).14 MAD has been further classified as two …

Contains fulltext : 48879.pdf (Publisher’s version ) (Closed access) OBJECTIVE: To investigate the contribution of MYH associated polyposis coli (MAP) among polyposis families in the Netherlands, and the prevalence of colonic and extracolonic manifestations in MAP patients. METHODS: 170 patients with polyposis coli, who previously tested negative for APC mutations, were screened by denaturing gradient gel electrophoresis and direct sequencing to identify MYH germline mutations. RESULTS: Homozygous and compound heterozygous MYH mutations were identified in 40 patients (24%). No difference was found in the percentage of biallelic mutation carriers between patients with 10-99 polyps or 100-1000 polyps (29% in both groups). Colorectal cancer was found in 26 of the 40 patients with MAP (65%) within the age range 21 to 67 years (median 45). Complete endoscopic reports were available for 16 MAP patients and revealed five cases with gastro-duodenal polyps (31%), one of whom also presented with a duodenal carcinoma. Breast cancer occurred in 18% of female MAP patients, significantly more than expected from national statistics (standardised morbidity ratio = 3.75). CONCLUSIONS: Polyp numbers in MAP patients were equally associated with the attenuated and classical polyposis coli phenotypes. Two thirds of the MAP patients had colorectal cancer, 95% of whom were older than 35 years, and one third of a subset of patients had upper gastrointestinal lesions. Endoscopic screening of the whole intestine should be carried out every two years for all MAP patients, starting from age 25-30 years. The frequent occurrence of additional extraintestinal manifestations, such as breast cancer among female MAP patients, should be thoroughly investigated.

Joubert syndrome (JS) is an autosomal recessive disorder presenting with congenital hypotonia evolving into ataxia, developmental delay, and either oculomotor apraxia or abnormalities of respiratory pattern or both. JS is characterised, using magnetic resonance imaging (MRI), by cerebellar vermian hypoplasia and a complex brain stem malformation called the “molar tooth sign” (MTS), consisting of thickened, elongated, and reoriented superior cerebellar peduncles and a deep interpeduncular fossa.1 JS has been classified into two groups, A and B, the latter being characterised by the occurrence of retinal and/or renal involvement.2 Key associated features of JS are retinal dystrophy and nephronophthisis, but other manifestations include ocular colobomas, liver fibrosis, and polydactyly. The variable involvement of other organs identifies a large spectrum of syndromes sharing the MTS (such as Arima, COACH, and Senior-Loken syndromes) which, together with JS, are termed Joubert syndrome related disorders (JSRD) or MTS related syndromes.3–5 To date, three genetic loci associated with JSRD have been mapped to chromosome 9q34.3 (JBTS1), 11p11.2–q12.3 (JBTS2), and 6q23 (JBTS3).6–9 Recently, mutations in the AHI1 gene have been identified in three JBTS3 linked families presenting with a pure cerebellar phenotype.10 Isolated nephronophthisis (NPH) is an autosomal recessive tubulointerstitial medullary kidney disease and is one of the most frequent monogenic causes of chronic renal failure in childhood. Four genes causing infantile or juvenile NPH have been cloned so far (NPHP1 to 4).11–14 Of these, NPHP1 is the most commonly mutated gene, being responsible for at least 50% of cases with juvenile NPH.15,16 A large homozygous deletion of the NPHP1 gene is found in more than 80% of patients, while less than 5% are compound heterozygote for the gene deletion and a point mutation on the other allele.16 Most patients with the NPHP1 deletion demonstrate …

1 For only few of these mutations, breakpoints have been determined at the sequence level because this information is often of little relevance in clinical diagnostics. Those gross deletions that have been analysed in greater detail most often show DNA sequences with direct or inverted similarity at 59 and 39 breakpoints. The presence of repeated sequences has suggested models that help to explain the formation of these mutations. 2 Mutations in the RB1 gene can cause retinoblastoma, a childhood tumour of the eye. We have searched for gross deletions in samples of constitutional and tumour DNA from patients with this tumour. Most of these samples had previously been screened for RB1 gene point mutations but with negative results. Using quantitative multiplex polymer- ase chain reaction (PCR) 3 we identified a spectrum of gross deletions that was heterogeneous with respect to extent and location. In three patients, we found deletions in a region that contains exon 24 of the RB1 gene. Further analysis showed that the 59 and 39 deletion breakpoints of these three mutations are located close to each other in an L1HS and MER21B element, respectively. 4 These two DNA elements belong to different classes of interspersed repetitive DNA. The regions surrounding the 59 and 39 breakpoints do not show any sequence similarity. However, they are localised at the borders of strong scaffold/matrix attachment elements that mark the position of recombinogenic DNA structures.

The prevalence of type 2 diabetes is higher in populations of Native American ancestry, and in Hispanic American populations formed by admixture between Europeans and Native Americans, than in populations of European ancestry.1 One approach to distinguishing between environmental and genetic explanations for this difference is to study the relationship of type 2 diabetes risk to individual admixture proportions (the proportions of an individual’s genome that are of European and Native American ancestry). With only a few markers informative for ancestry, it is possible to estimate the average admixture proportions of any Hispanic American population. In such analyses, it has been possible to demonstrate that the prevalence of type 2 diabetes in Hispanic Americans in the south western United States varies with the average Native American admixture proportion of these populations.2–4 In the Native American population of Gila River, Arizona, USA, European admixture is associated with lower prevalence of type 2 diabetes.5 However, it has not been possible to demonstrate an association of type 2 diabetes with individual admixture proportions within an Hispanic American population. To estimate the admixture proportions of an individual accurately requires a larger panel of markers: at least 40 markers with average frequency differentials of 0.6 are required to estimate the admixture of an individual with a standard error of no more than 0.1.6 It is now possible to identify relatively large numbers of such ancestry informative markers from data accumulating in the public domain. For this study we typed a panel of 21 markers chosen to have large differences in frequency between European, Native American, and West African ancestry. The possible relationship of type 2 diabetes risk to individual admixture proportions within Hispanic American populations complicates the interpretation of associations of type 2 diabetes with candidate gene polymorphisms within these …

Crohn’s disease (MIM 266600) and ulcerative colitis (MIM 191390) are the major forms of inflammatory bowel disease (MIM 601458), the prevalence of Crohn’s disease being more than 1/1000 in the Western countries.1 Inflammatory bowel disease is characterised by chronic relapsing intestinal inflammation, and its pathogenesis probably involves microbial, immunological, environmental, and genetic factors.2,3 Recent genetic association studies have shown that sequence variations in the Caspase Activating Recruitment Domain ( CARD15 ) gene (MIM605956, formerly named NOD2) on chromosome 16q are a strong genetic factor for Crohn’s disease but not for ulcerative colitis.4–6 CARD15 represents the first major Crohn’s disease susceptibility gene identified, and its identification might facilitate the uncovering of other genetic factors for the disease. The matrix metalloproteinases (MMP) are a group of matrix degrading enzymes that play an important role in the pathogenesis of various inflammatory diseases including osteoarthritis, rheumatoid arthritis, atherosclerosis, cancers, and inflammatory bowel disease.7 We have shown that, of four MMPs studied (interstitial collagenase, gelatinase A and B, and stromelysin-1), stromelysin-1 in particular is directly involved in mucosal destruction following T cell activation in the human fetal gut.8 Furthermore, patients with Crohn’s disease have increased expression of stromelysin-1 in the mucosa at both the mRNA and protein levels.9 Microarray techniques have demonstrated that stromelysin-1 expression is increased 8.7-fold in the mucosa of patients with Crohn’s disease compared with healthy controls (Pender SLF, unpublished data), and have also shown that stromelysin-1 expression is 8.2-fold higher relative to controls in PWM stimulated human fetal gut explant culture.10 Thus, although the stromelysin-1 gene on chromosome 11q23 is not located within the particular chromosomal regions (19p13, 16q12, 16p, 14q11–q12, 12p13.2–q24.1, 6p, 5q31, and 1p36) that have been shown to be in linkage with inflammatory bowel disease (MIN 266600), it is a strong …

Hereditary optic atrophy is a generic term that refers to a heterogeneous group of genetic disorders for which several modes of inheritance have been described.1 The most common forms of optic atrophy are autosomal dominant optic atrophy (ADOA, OMIM 165500) and Leber’s hereditary optic neuropathy (LHON, OMIM 53500). ADOA, which generally starts in childhood, is characterised by a progressive decrease in visual acuity, blue-yellow dyschromatopsia, loss of sensitivity in the central visual field, and optic nerve pallor. Mutations in the optic atrophy 1 ( OPA1 ) gene, located on chromosome 3q28–q29, are implicated in about 60–80% of the cases of ADOA.1–4 OPA1 encodes for a mitochondrial dynamin related protein. This protein, anchored to the mitochondrial inner membrane, contributes to mitochondrial structure and biogenesis.5,6 A second gene involved in ADOA, not yet identified, has been mapped to chromosome 18q ( OPA4 , OMIM 605293).7 LHON, which is caused by specific mutations in mitochondrial DNA, is inherited maternally.8 It is characterised by severe bilateral optic atrophy responsible for acute or subacute visual loss, usually starting between the ages of 18 and 35. Other forms of hereditary optic atrophy include X linked optic atrophy (XLAO, OPA2 , OMIM 311050)9 and autosomal recessive optic atrophy (AROA), for which a first locus has recently been mapped to chromosome 8q.10 Finally, more than 15 disorders—mostly inherited in the autosomal recessive mode—have combined optic atrophy and extraocular anomalies. Among these syndromic optic atrophies, type III 3-methylglutaconic aciduria (MGA) (OMIM 258501), also known as the Costeff syndrome11 or the optic atrophy plus syndrome, consists of early onset bilateral optic atrophy, later onset spasticity, extrapyramidal signs, and cognitive deficit. Urinary excretion of 3-methyl glutaconic acid and increased plasma 3-methylglutaric acid levels are the hallmarks of MGA.12 Linkage analyses, undertaken in MGA …

Only recently, mutations of the RAPSN gene have been recognised as causing acetylcholine receptor deficiency at the motor endplate resulting in early and late onset forms of congenital myasthenic syndromes (CMS).1–9 In most studies a single missense mutation of RAPSN (N88K) was detected either homozygously or compound heterozygously in numerous, unrelated patients of European and North American origin. Based on the analysis of a small number of intragenic single nucleotide polymorphisms (SNPs) and/or extragenic, polymorphic repeat markers, we hypothesised that RAPSN (N88K) may derive from a common founder.7 However, this hypothesis was disputed in a recent report in the Journal of Medical Genetics.10 In this study, 12 independent RAPSN (N88K) alleles from white North American CMS patients were compared to 37 wild type chromosomes. Five intragenic SNPs and two extragenic microsatellite markers appeared to be in linkage disequilibrium with the mutation, whereas four extragenic microsatellite markers failed to prove a significant association.10 To resolve this question we analysed 41 independent RAPSN (N88K) alleles using 21 SNPs flanking RAPSN on chromosome 11p11.11 We collected 21 CMS patients harbouring RAPSN (N88K) either homozygously (n = 20) or compound heterozygously (n = 1). Screening for the mutation N88K (264C→A) in exon 2 of the RAPSN gene was performed as described previously.7 Patients originated from Germany (n = 5), Austria (n = 1), Italy (n = 1), France (n = 2), the United Kingdom (n = 10), and the Indian subcontinent (n = 2). Consanguinity was not reported for any of the families. Most of the patients have been described, previously: patients G1–G4, Au1, UK10, and It1 (patients 1–7 in Muller et al 7), patients UK1–7 (patients 3, 9, 11, 12, 13, 15, and 16 in Burke et al 6), patient Ind2 (patient 1 in Burke et al 6), patient Fr1 (patient 1 in Richard et al 8), and patient Fr2 (in Yasaki …

The cytoskeleton comprises three filamentous systems: microfilaments, intermediate filaments, and microtubules. In epithelial cells, type I keratins such as keratin 18 (KRT18) and type II keratins such as keratin 8 (KRT8) polymerise to form the intermediate filaments. KRT18 and KRT8 represent the major keratins expressed in single-layered epithelia of the gastrointestinal tract including liver and pancreas.1 Animal studies suggest KRT8 and KRT18 have a hepatoprotective role against mechanical and toxic injury.2 Transgenic mice overexpressing mutant KRT18 display fragile hepatocytes with disrupted cytoskeleton filaments.3 These mice developed chronic hepatitis and were more susceptible to liver injury in comparison to mice overexpressing wild type KRT18.4 The viability of KRT8 null mice depends on the genetic background of the different mouse strains suggesting further genetic factors contribute to the resultant phenotype. For instance, in one mouse strain KRT8 -deficient mice died during embryonic development due to extensive liver haemorrhage.5 However, in another strain 55% of the KRT8 -deficient mice had a normal life expectancy but developed signs of inflammatory bowel disease and in some cases a mild inflammation of the liver.6 A recent report emphasises the importance of Keratin 8 for the formation of an intact placental barrier function for the viability of KRT8 -deficient embryos. These findings argue in favour of an extraembryonic defect responsible for lethality of these embryos.7 Furthermore, KRT8 null mice showed an abnormal histological liver architecture and were more vulnerable to liver damage after exposure to hepatotoxic substances compared to wild type mice.8–10 The above mentioned results support the hypothesis that keratin mutations might predispose humans to liver disease. Indeed, Ku et al described an association between two KRT8 mutations and cryptogenic cirrhosis. A heterozygous single base substitution involving a Gly to Cys at codon 62 (G62C) was found …

In 1967, Bachman described a “hereditary peripheral dysostosis” which affected a mother and her two children.1 What was later considered as multiple epiphyseal dysplasia combined with phalangeal cone shaped epiphyses2 was renamed angel shaped phalangoepiphyseal dysplasia (ASPED) and considered as a genetic bone marker.3 ASPED represents a further variety of multiple epiphyseal dysplasia and is transmitted as an autosomal dominant trait. It is radiologically diagnosed by the characteristic angel shape of the middle phalanges, typical metacarpophalangeal pattern profile, and epiphyseal changes in the hips. The angel shape of the middle phalanges is an isolated bone variation, similar to the non-syndromal, cone shaped epiphyses of type 12.3 Clinical manifestations in ASPED are not restricted to the hands, and the original paper reported on various combinations of angel shaped phalanges, hip dysplasia, and hypodontia.1 Patients range in stature from short to normal. Osteoarthritis of the hips can be significant, with severe intermittent hip pain. Hyperextensible interphalangeal joints of the fingers have been documented, as well as retarded bone age. Late eruption of deciduous teeth or persistent primary lower incisors have been described.3 Hypodontia was noted in four out of seven patients in Giedion’s cohort, and in 1.6 to 9.6% in the general population.4 Brachydactyly type C (BDC) is characterised by shortening of the first metacarpal and of the second, third, and fifth middle phalanges.5 Other common hand findings include ulnar deviation of the index finger and polyphalangy. Several reports on BDC emphasise variability of findings such as talipes, shortening of the middle phalanges of the toes, hip dysplasia, and short stature, but have not emphasised the presence of hypodontia or angel shaped epiphyses.6,7 CDMP-1 (also known as GDF5) is a secreted signalling molecule that participates in skeletal morphogenesis. CDMP-1 has been detected …

Mitochondrial myopathies are often associated with point mutations in mitochondrial DNA (mtDNA), and are usually maternally inherited. However, they may also present as an isolated myopathy, often with ptosis and ophthalmoparesis,1 or with isolated exercise intolerance.2 In eight patients with exercise intolerance described by us in 1999,2 there was no evidence of maternal inheritance, muscle histochemistry showed cytochrome c oxidase (COX) positive ragged red fibres, biochemistry showed complex III deficiency, and molecular genetic analysis revealed different mutations in the mitochondrial cytochrome b gene (CYB) . Several other patients with lifelong exercise intolerance harboured mutations in other mtDNA protein coding genes.3 Characteristically, these mutations are not maternally inherited and are abundant (more than 90%) in skeletal muscle, where they coexist with smaller amounts of wild type mtDNA genomes. As a rule, the mutations are not present in other tissues and, surprisingly, are not found in cultured myoblasts, indicating that they are somatic mutations of skeletal muscle. However, the mechanism by which these mutations accumulate in muscle remains unknown. As the clinical presentation of all patients (lifelong progression of clinical symptoms), suggested that the molecular defect may accumulate over time, we looked for duplications in the D-loop as putative sources of replication advantage or disadvantage for mutant mtDNAs. Here, we report our findings in 10 patients harbouring different mtDNA mutations restricted to skeletal muscle; 5 patients with point mutations and 5 with single deletions. In all five patients with point mutations, we identified a 652 bp duplication in the mtDNA control region, which altered the promoter and replication elements. The duplication was restricted to skeletal muscle mtDNA, and analysis of subcloned PCR fragments encompassing both the site of the point mutation and the region of the duplication suggested that the duplication segregates independently from the point mutation. Our …

Schizophrenia (MIM 181500) is a severe, common, and heterogeneous psychiatric disorder that affects 1% of the world’s population. The disorder is characterised by hallucinations, delusions, disorganised thoughts, and various cognitive and affective impairments. As a leading cause of psychiatric admissions, schizophrenia accounts for a considerable portion of healthcare expenditure and is a major public health concern. Family, twin, and adoption studies have shown that a genetic factor is associated with susceptibility to schizophrenia.1–4 The number and nature of genes that influence susceptibility to schizophrenic illness, as well as their interaction with environmental factors, are unknown. Despite decades of research on anatomical, physiological, and biochemical changes possibly associated with schizophrenia, insight into the aetiology is only fragmentary. Mapping of genes that contribute to the development of schizophrenic disorders by means of linkage and association studies may help identify and characterise causal factors. Although no single causative gene has been identified to date, several chromosomal loci with positive linkage results are under investigation as tentative susceptibility loci for schizophrenia, including chromosomes 6, 8, 10, 13, and 22 to remove obstacles of locus heterogeneity among sampled populations.5 Cao et al first reported possible linkage to 6q21–22 in two independent American samples of patients with schizophrenia: at locus D6S474 using sibling pair analysis in 63 independent sibling pairs (p = 0.00018) and at D6S424, which is about 14 centimorgan (cM) near D6S474 in a second sample of 87 independent sibling pairs (p = 0.00095).6 The same group reported modest support for linkage to D6S424 in a third sample in 1999 that consisted of 54 American and Australian sibling pairs.7 In a study with combined samples (141 independent sibling pairs), they obtained a non-parametric likelihood of odds (LOD) score of 3.82 (p = 0.000014).7 Several other studies also supported a susceptibility locus for schizophrenia on …