A p.R870H mutation in the beta-cardiac myosin heavy chain 7 gene causes familial hypertrophic cardiomyopathy in several members of an Indian family.

Familial hypertrophic cardiomyopathy is an autosomal dominant genetic disorder characterized mainly by left ventricular hypertrophy and myocyte disarray; it is the most common cause of sudden death in otherwise healthy individuals. More than 270 mutations in genes encoding the cardiac sarcomere have been identified. Attempts to establish a genotype-phenotype correlation for each of the mutations have not been highly successful. It has been suggested that additional genetic loci, as well as nongenetic factors such as lifestyle, gender and age, may play a role in modulating the clinical presentation of the disease. The p.R870H mutation has been identified as the cause of familial hypertrophic cardiomyopathy in an Indian family. The results indicate that the disease phenotype varied among various affected members of the family, and the variation may be attributed to factors, such as gender and gene dosage.

Molecular genetics of familial hypertrophic cardiomyopathy (FHC).

Familial hypertrophic cardiomyopathy is an autosomal dominant disease with a wide range of clinical features from benign to severe, and is the most common cause of sudden death in otherwise healthy individuals. The two prominent clinical features are left ventricular hypertrophy and myocyte/myofibrillar disarray. The former is responsible for clinical symptoms such as breathlessness and angina, whereas the latter may lead to sudden cardiac death. The last decade has seen an enormous improvement in our understanding of the molecular genetics of this disorder. The clinical heterogeneity has been linked to genetic heterogeneity; mutations in nine genes encoding sarcomere proteins have been shown to be the molecular basis for the disorder. However, attempts to establish a genotype-phenotype correlation for each of the more than 100 mutations that have been identified have not been highly successful. Additional genetic loci, as well as nongenetic factors such as lifestyle, sex, and age, have also been shown to play a role in modulating the clinical presentation of the disease. How each mutation results in hypertrophy and/or myofibrillar disarray is unclear. The present review discusses the current status of the molecular genetic characterization of this important disorder.

Molecular genetic analyses of beta-thalassemia in South India reveals rare mutations in the beta-globin gene.

beta-Thalassemia is the most prevalent single-gene disorder. Since no viable forms of treatment are available, the best course is prevention through prenatal diagnosis. In the present study, the prevalence of beta-thalassemia was extensively investigated in the South Indian population, especially from the state of Andhra Pradesh. Screening for causal mutations was carried out on genomic DNA isolated from patient blood samples by using the routine reverse dot blot (RDB) and amplification refractory mutation system-polymerase chain reaction (ARMS-PCR) techniques. DNA sequencing was performed wherever necessary. Among the nine mutations identified, four, including IVS-1-5 (G-C) (IVS1+5G>T), codon 41/42 (-TTCT) (c.124_127delTTCT), codon 15 (G-A) (c.47G>A), and HbS (sickle mutation) (c.20A>T) mutations, accounted for about 98% of the total positive cases. Two mutations viz. codon 8/9 (+G) (c.27_28insG) and HbE (codon 26 G-A) (c.79G>A) exhibited a very low frequency of occurrence, whereas the IVS-1-1 (G-T) (IVS1+1G>T) and the 619 bp deletion (c.366_494del) mutations were absent. We also identified certain rare mutations during the diagnostic evaluation. Gene sequencing confirmed the codon 30 (G-C) (c.92G>C) mutation and the rare codon 5 (-CT) (c.17_18delCT) and IVS-II-837 (T-G) (IVSII-14T>G) mutations. This is the first report of the IVS II 837 mutation in the Indian population. We also report a novel diagnostic application during RDB-based screening for the detection of the (c.92G>C) mutations. Such a comprehensive mutation screening is essential for prenatal diagnosis of beta-thalassemia and control of this highly prevalent monogenic disorder in the Indian population.