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Long QT syndrome (LQTS) is a rare and clinically heterogeneous inherited disorder characterized by a long QT interval on the electrocardiogram, increased risk of syncope and sudden death caused by arrhythmias. This syndrome is mostly caused by mutations in genes encoding various cardiac ion channels. The clinical heterogeneity is usually attributed to variable penetrance. One of the reasons for this variability in expression could be the coexistence of common single nucleotide polymorphisms (SNPs) on LQTS-causing genes and/or unknown genes. Some synonymous and nonsynonymous exonic SNPs identified in LQTS-causing genes may have an effect on the cardiac repolarization process and modulate the clinical expression of a latent LQTS pathogenic mutation. We report the molecular pattern of 44 unrelated patients with LQTS using denaturing high-performance liquid chromatography analysis of the KCNQ1, KCNH2, SCN5A, KCNE1 and KCNE2 genes. Forty-five disease-causing mutations (including 24 novel ones) were identified in this cohort. Most of our patients (84%) showed complex molecular pattern with one mutation (and even two for four patients) associated with several SNPs located in several LQTS genes. [ABSTRACT FROM AUTHOR]

Abstract: We report the fifth case of neonatal form of type C2 (NP-C2) Niemann-Pick disease with early and fatal respiratory distress. Eleven families presenting such cases are known to date in the world. Since December 2000, isolation of the underlying gene HE1/NPC2 and its mutations has allowed major advances in diagnosis. Case report. – Elisa was born in May 2000. NP-C2 disease was associated with severe respiratory distress leading to death at the age of four months. On the next pregnancy in September 2000, prenatal diagnosis was performed by means of biological tests that required four weeks response time. In December 2000, isolation of the HE1/NPC2 gene located to 14q24.3 and of some of its mutations allowed to characterize the patient as being homozygote for the nonsense mutation E20X. On the the two next pregnancies, prenatal diagnosis was performed at 12 SA, in 48 hours, by the means of mutation analysis. The last fetus was heterozygote for the mutation E20X, allowing the birth at term of a healthy male newborn baby. Conclusion. – Niemann-Pick type C disease is a rare lysosomal lipid storage disease with severe prognosis. It is characterized by abnormalities of intracellular transport of endocytosed cholesterol. Diagnosis relies on biological tests that require cultured cells. Genetic heterogeneity defines two different genetic complementation groups C1 and C2. Severe and early respiratory distress is more likely to be associated with the rare type C2. Since December 2000, after identification of the disease-causing mutations in the proband, mutation analysis of gene HE1/NPC2 on direct chorionic villus samples allows early and fast (48 hours) prenatal diagnosis. [Copyright &y& Elsevier]

Niemann-Pick disease type C (NPC) is an autosomal recessive neurovisceral lipid storage with a wide spectrum of clinical phenotypes. At the cellular level, the disorder is characterized by accumulation of unesterified cholesterol and glycolipids in the lysosomal/late endosomal system. Approximatively 95% of patients have mutations in the NPC1 gene (mapped at 18q11) which encodes a large membrane glycoprotein primarily located to late endosomes. The remainder have mutations in the NPC2 gene (mapped at 14q24.3) which encodes a small soluble lysosomal protein with cholesterol-binding properties. The identical biochemical patterns observed in NPC1 and NPC2 mutants suggest that the two proteins function in a coordinate fashion. Identification of mutations revealed a complex picture of molecular heterogeneity, allowing genotype - phenotype correlations for both genes and providing insights into structure - function relationships for the NPC1 protein. Although a whole body of evidence suggests that the NPC1 and NPC2 proteins are involved in the cellular postlysosomal/late endosomal transport of cholesterol, glycolipids and other cargo, their precise functions and relationship remain unclear and are currently the subject of intense investigation. These studies, conducted in various models, should ultimately lead to a better understanding of the pathophysiology of NPC and new therapeutic approaches. [ABSTRACT FROM AUTHOR]

Abstract: Primary hypertrophic cardiomyopathy is a relatively frequent disease (1/500) which results from a mutation in a gene encoding a sarcomeric protein. In a series of 184 cases, nearly half (46 %) were secondary to a mutation in one of the 4 following genes : MYBPC3, MYH7, TNNI3, TNNT2. In Fabry disease, an exclusive or nearly exclusive cardiac expression is possible and referred to as “cardiac variant”. The hypertrophic cardiomyopathy of Fabry disease is usually unspecific. Two series reported a prevalence of Fabry disease of about 6% among male cases. An Italian series of 34 female cases with hypertrophic cardiomyopathy demonstrated that it was feasible to diagnose Fabry disease in females by screening for specific lesions in myocardial biopsies. We detected a patient who initially presented with a common hypertrophic cardiomyopathy except that his ECG showed depression of ST segment and inversion of T wave in leads D1, VL and in precordial leads. The family history revealed several affected relatives and female carriers. In conclusion, an isolated common hypertrophic cardiomyopathy may be secondary to Fabry disease. Male patients should be screened systemically for enzyme defect except in cases of father-to-son transmission. In females, an affected male relative should be searched for screening or the GLA gene should be sequenced. It is important to think about a putative Fabry disease in cases with hypertrophic cardiomyopathy not associated with any obvious cause. [ABSTRACT FROM AUTHOR]

Summary: A 10-year-old child was hospitalized for bradycardia during a viral infection with chikungunya. His history showed unexplored episodes of bradycardia. Cardiologic explorations revealed cardiac sinus node dysfunction (SD). Mutational screening of the SCN5A gene showed that this case was a compound heterozygote for p.Ala735Val and p.Asp1792Asn missense mutants. Five years later, the child underwent a pacemaker insertion after an electrophysiological study performed during an atrial flutter access. [ABSTRACT FROM AUTHOR]

Abstract: Hypertrophic cardiomyopathy (HCM), a common and clinically heterogeneous disease characterized by unexplained ventricular myocardial hypertrophy and a high risk of sudden cardiac death, is mostly caused by mutations in MYH7 and MYBPC3 genes. As 70% of MYBPC3 mutations introduce a premature termination codon, the purpose of the current study was to report the prevalence of large MYBPC3 rearrangements. A large French cohort of 100 HCM patients, for whom no putatively causative point mutations were identified previously in the most prevalent HCM-causing genes, was investigated using an MLPA methodology. One HCM patient was identified to carry a large MYBPC3 rearrangement (<1%). This patient presents a 3505-bp deletion, which begins in the intron 27 and ends 485 bp after the MYBPC3 stop codon (g.47309385_47312889del). It was originated by recombination of a 296 bp AluSz sequence located in intron 27 and a 300 bp AluSx sequence located immediately downstream of exon 35. This study allowed the characterization of the first large MYBPC3 deletion reported in the literature. However, it appears that MLPA strategy, that moderates the identification of large MYBPC3 rearrangements, might confirm a clinical diagnosis only in a small number of patients (<1%). [Copyright &y& Elsevier]