Abstract 16901: Exome Sequencing and Haplotype Sharing Analyses Result in the Identification of Novel Genetic Causes of Cardiomyopathies
Introduction Inherited cardiomyopathies are genetically heterogeneous diseases that can be caused by mutations in many different genes. To identify novel genetic causes of cardiomyopathy, exome sequencing and haplotype sharing analyses were employed.
Methods Targeted resequencing of the coding regions of 48 known cardiomyopathy genes was performed in index patients (48 patients analyzed; >36 patients in progress), to exclude patients that carry mutations in known genes. Patients/families that were still without a pathogenic mutation after targeted resequencing (currently ten dilated cardiomyopathy (DCM) and three arrhythmogenic cardiomyopathy (AC) families) were selected for haplotype sharing test combined with exome sequencing in at least two affected family members. In silico analyses (ie. BWA and GATK tools, filtering for known variants in dbSNP, 1000 genomes, Go-NL, etc.) were performed.
Results The coverage within exome sequencing data varied significantly between genes. However, the coverage performance is insufficient to rely on exome sequencing analysis only, supporting our targeted resequencing pre-screening approach. Exome data mapping and variants calling were finished for 5 out of 13 families (ten DCM and three AC families). Our exome studies resulted in the identification of (1) a novel nonsense variant c.59845C>T (p.Arg19949X) in the titin gene (TTN) in one multigenerational DCM family that was shown to co-segregate with disease; (2) a most-likely pathogenic homozygous missense mutation in a nuclear encoded mitochondrial protein in a family with autosomal recessive DCM; (3) potentially pathogenic mutations in two other DCM families. In all cases, these mutations were located on (one of) the longest shared haplotypes, strongly supporting the involvement in disease in these families. The analysis of the other families is in progress, as well as studies on the role of the above mentioned genes in cardiomyopathies.
Conclusion This study shows that our combined strategy is highly promising in identifying novel gene defects in cardiomyopathies and exome sequencing is likely to become the method of choice for disease gene identification in cardiomyopathy for the coming years.
- © 2012 by American Heart Association, Inc.