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Purpose: The study's purpose was to compare acarbose and maltose as inhibitors of maltase-glucoamylase activity for determining acid alpha-glucosidase activity in dried blood spot specimens for early identification of patients with infantile Pompe disease, a severe form of acid alpha-glucosidase deficiency., Methods: Acid alpha-glucosidase activities in dried blood spot extracts were determined fluorometrically using the artificial substrate 4-methylumbelliferyl-alpha-D-pyranoside. Acarbose or maltose was used to inhibit maltase-glucoamylase, an enzyme present in polymorphonuclear neutrophils that contributes to the total alpha-glucosidase activity at acidic pH., Results: Complete discrimination between patients with proven infantile Pompe disease (n = 20), obligate heterozygotes (n = 16), and controls (n = 150) was achieved using 8 micromol/L acarbose as the inhibitor. Higher acarbose concentration (80 micromol/L) did not improve the assay. By using 4 mM maltose as the inhibitor, heterozygotes and patients were not completely separated. The results using acarbose compared well with those using the skin fibroblast assay in the same group of patients with proven infantile Pompe disease., Conclusion: Acid alpha-glucosidase activity measurements in dried blood spot extracts can reliably detect infantile Pompe disease in patients. The convenience of collecting and shipping dried blood specimens plus rapid turnaround time makes this assay an attractive alternative to established methods.

Objective: We sought to evaluate the knowledge of probable outcome by medical personnel for in-hospital and out-of-hospital cardiac arrests, and self-reported history of CPR training referrals for family members of cardiac patients., Methods: One hundred people from each of three population lists were randomly selected at a large, urban school of medicine and affiliated medical center: (1) year III and IV medical students; (2) residents in family medicine, emergency medicine, internal medicine, anesthesia, and surgery; (3) attending physicians in the same departments. A questionnaire was distributed that elicited estimates of in-hospital and out-of-hospital cardiac arrest (IHCA and OHCA, respectively) survival rates, and CPR training referral history. Estimates were compared against published data for accuracy (IHCA: 5-20%; OHCA 1-10%), Results: The overall response rate was 63%. Accurate in-hospital cardiac arrest estimates [% (95% CI)] of survival were provided by 51.1% (36.8-63.4%), 47.3% (35.9-58.7%), and 36.7% (23.2-50.2%) of students, residents, and attending physicians, respectively. Accurate out-of-hospital estimates of survival were provided by 51.1% (36.8-63.4%), 52.1% (40.6-63.5%), and 70.8% (57.9-83.7%), respectively. Most thought that family members of cardiac patients ought to be CPR trained (92.6%). However, few had referred any for training in the past year (16.5%). There was strong support across respondent groups for including death notification information in the ACLS training program, with 80.4% of all respondents in favor., Conclusions: This study demonstrates that medical experience is not associated with accurate estimates of cardiac arrest survival. Overwhelmingly, medical personnel believe family members should be trained to perform CPR, however, few refer family members for CPR training.

Glycogen storage disease type IV (GSD-IV) is an autosomal recessive genetic disorder due to a deficiency in the activity of the glycogen branching enzyme (GBE). A deficiency in GBE activity results in the accumulation of glycogen with fewer branching points and long, unbranched outer chains. The disorder results in a variable phenotype, including musculoskeletal, cardiac, neurological, and hepatic involvement, alone or in continuum, which can be identified at any stage of life. The classic form of GSD-IV is a hepatic presentation, which presents in the first 18 months of life with failure to thrive, hepatomegaly, and cirrhosis that progresses to liver failure, resulting in death by age 5 years. A severe congenital musculoskeletal phenotype with death in the neonatal period has also been described. We report an unusual case of congenital musculoskeletal presentation of GSD-IV with stable congenital hypotonia, gross motor delay, and severe fibro-fatty replacement of the musculature, but no hepatic or cardiac involvement. Molecular analysis revealed two novel missense mutations with amino acid changes in the GBE gene (Q236H and R262C), which may account for the mild phenotype., (Copyright 2006 Wiley-Liss, Inc.)

Background: Homozygosity and compound heterozygosity for the short chain acyl-CoA dehydrogenase (SCAD) gene sequence variants 625G-->A and 511C-->T are associated with ethylmalonic aciduria (EMA), a biochemical indicator of SCAD deficiency. The clinical and biochemical implications of these variants are not fully understood. The effect of these variants on the accumulation of butyrylcarnitine by fibroblasts in culture was studied., Methods: In vitro acylcarnitine profiling in fibroblasts was carried out using [U-13C]-labeled or unlabeled palmitate in the presence of excess L-carnitine, with or without a medium chain acyl-CoA dehydrogenase (MCAD) inhibitor. Acylcarnitines were analyzed using tandem mass spectrometry. 625G/625G (wild type), 625G/625A and 625A/625A (variant) control fibroblasts were compared with fibroblasts from patients homozygous for inactivating SCAD mutations (SCAD deficient) and from patients with EMA who were homozygous or compound heterozygous for the SCAD variants., Results: Variant control and patient fibroblasts accumulated moderate amounts of butyrylcarnitine compared with wild-type controls and in contrast to the significant amount of butyrylcarnitine accumulated by SCAD deficient fibroblasts, regardless of incubation conditions., Conclusions: Moderately reduced SCAD activity associated with SCAD variants can be detected using in vitro acylcarnitine profiling methods, which may be used as an indirect measure of SCAD activity.

Tandem mass spectrometry was adopted for newborn screening by North Carolina in April 1999. Since then, three infants with short-chain acyl-CoA dehydrogenase (SCAD) and one with isobutyryl-CoA dehydrogenase deficiency were detected on the basis of elevated butyrylcarnitine/isobutyrylcarnitine (C4-carnitine) concentrations in newborn blood spots analyzed by tandem mass spectrometry. For three SCAD-deficient infants, biochemical evaluation included a plasma acylcarnitine profile with markedly elevated C4-carnitine, urine organic acid analysis with markedly elevated ethylmalonic and 2-methylsuccinic acids, and markedly elevated [U-13C]butyrylcarnitine concentrations in medium from fibroblasts incubated with [U-13C]palmitic acid and excess l-carnitine, consistent with classic SCAD deficiency. Two of three infants diagnosed with classic SCAD deficiency remained asymptomatic; however, the third infant presented with seizures and a cerebral infarct at 10 wk of age. All three infants had putatively inactivating mutations in both alleles of the SCAD gene. The highly elevated plasma C4-carnitine levels in the three infants detected by newborn screening tandem mass spectrometry differentiated them from infants and children who were homozygous or compound heterozygous for one of two SCAD gene susceptibility variations; for the latter group the C4-carnitine levels were normal. Isobutyryl-CoA dehydrogenase deficiency in a fourth infant was confirmed after isolated elevation of C4-carnitine in the acylcarnitine profile.

Unlabelled: Glycogen storage disease type Ia (GSD Ia) is caused by mutations in the G6PC gene encoding the phosphatase of the microsomal glucose-6-phosphatase system. GSD Ia is characterized by hepatomegaly, hypoglycemia, lactic acidemia, hyperuricemia, hyperlipidemia and short stature. Other forms of GSD I (GSD I non-a) are characterized by the additional symptom of frequent infections caused by neutropenia and neutrophil dysfunction. GSD I non-a is caused by mutations in a gene encoding glucose-6-phosphatase translocase (G6PT1). We report on the molecular genetic analyses of G6PC and G6PT1 in 130 GSD Ia patients and 15 GSD I non-a patients, respectively, and provide an overview of the current literature pertaining to the molecular genetics of GSD I. Among the GSD Ia patients, 34 different mutations were identified, two of which have not been described before (A65P; F177C). Seventeen different mutations were detected in the GSD I non-a patients. True common mutations were identified neither in GSD Ia nor in GSD I non-a patients., Conclusion: Glycogen storage disease type Ia and and type I non-a are genetically heterogenous disorders. For the diagnosis of the various forms of glycogen storage disease type I, molecular genetic analyses are reliable and convenient alternatives to the enzyme assays in liver biopsy specimens. Some genotype-phenotype correlations exist, for example, homozygosity for one G6PC mutation, G188R, seems to be associated with a glycogen storage disease type I non-a phenotype and homozygosity for the 727G>T mutation may be associated with a milder phenotype but an increased risk for hepatocellular carcinoma.

Objective: To develop diagnostic criteria for a familial form of antiphospholipid antibody syndrome (APS), identify families with >1 affected member, examine possible modes of inheritance, and determine linkage to potential candidate genes., Methods: Family members of probands with primary APS were analyzed for clinical and laboratory abnormalities associated with APS. Families with > or =2 affected members were analyzed by segregation analysis and typed for candidate genetic markers., Results: Seven families were identified. Thirty of 101 family members met diagnostic criteria for APS. Segregation studies rejected both environmental and autosomal recessive models, and the data were best fit by either a dominant or codominant model. Linkage analysis showed independent segregation of APS and several candidate genes., Conclusion: Clinical and laboratory criteria are essential to identify the spectrum of disease associated with APS. We believe a set of criteria was developed that can precisely define affected family members with APS. Modeling studies utilizing these criteria strongly support a genetic basis for disease in families with APS and suggest that a susceptibility gene is inherited in an autosomal dominant pattern. However, in these families, APS was not linked with HLA, Fas, or other candidate genes, including beta2-glycoprotein 1, HLA, T cell receptor beta chain, Ig heavy chain, antithrombin III, Fas ligand, factor V, complement factor H, IgK, and Fas.

Primary ciliary dyskinesia (PCD) is a genetic disease characterized by abnormal ciliary structure and function, impaired mucociliary clearance, and chronic middle ear, sinus, and lung disease. PCD is associated with situs inversus in approximately 50% of the patients. One proposed explanation for this relationship is that normal ciliary function plays a role in normal organ orientation, whereas organ orientation in PCD is a random event because of dysfunctional cilia in early embryonic development. Another hypothesis for the association between PCD and situs inversus is that mutated genes in PCD not only cause defective cilia, but are also linked to the control of organ laterality, such that abnormalities in this molecular pathway result in random left-right asymmetry. We report on a set of monozygotic twin women with PCD. In both patients, deficiency of the inner dynein arms was noted on ciliary ultrastructural analysis, associated with a clinical syndrome of bronchiectasis, chronic sinusitis, and middle ear disease. One of the twins has situs solitus, the other has situs inversus totalis. DNA analysis confirmed that the twins are monozygotic. This is consistent with the hypothesis that situs inversus occurring in patients with primary ciliary dyskinesia is a random but "complete" event in the fetal development of patients with PCD.

Peutz-Jeghers syndrome (PJS) was recently mapped in a single report to the telomeric region of chromosome 19p (A. Hemminki et al., Nat. Genet., 15: 87-90, 1997). Our studies confirm this location and provide further localization of the PJS locus. In the five families examined, there were no recombinants with the marker D19S886. The multipoint log odds score at D19S886 is 7.52, and we found no evidence for genetic heterogeneity. We also found that all carriers expressed the PJS phenotype and no noncarriers displayed PJS sequellae, indicating complete penetrance with no sporadic cases.

Genotoxic evaluation of a widely used glucocorticoid, hydrocortisone, was undertaken using a battery of in vitro and in vivo test systems. Human lymphocyte cultures and mouse bone marrow studies (micronuclei and sister chromatid exchange analyses) showed the drug to be very potent clastogen. However, the Ames/Salmonella assay both with and without S9 did not show an increase in the His+ revertants.