Genetic Insights from Consanguineous Cardiomyopathy Families

Abstract

Inherited cardiomyopathies are a prevalent cause of heart failure and sudden cardiac death. Both hypertrophic (HCM) and dilated cardiomyopathy (DCM) are genetically heterogeneous and typically present with an autosomal dominant mode of transmission. Whole exome sequencing and autozygosity mapping was carried out in eight un-related probands from consanguineous Middle Eastern families presenting with HCM/DCM followed by bioinformatic and co-segregation analysis to predict the potential pathogenicity of candidate variants. We identified homozygous missense variants in <i>TNNI3K</i>, <i>DSP</i>, and <i>RBCK1</i> linked with a dilated phenotype, in <i>NRAP</i> linked with a mixed phenotype of dilated/hypertrophic, and in <i>KLHL24</i> linked with a mixed phenotype of dilated/hypertrophic and non-compaction features. Co-segregation analysis in family members confirmed autosomal recessive inheritance presenting in early childhood/early adulthood. Our findings add to the mutational spectrum of recessive cardiomyopathies, supporting inclusion of <i>KLHL24</i>, <i>NRAP</i> and <i>RBCK1</i> as disease-causing genes. We also provide evidence for novel (recessive) modes of inheritance of a well-established gene <i>TNNI3K</i> and expand our knowledge of the clinical heterogeneity of cardiomyopathies. A greater understanding of the genetic causes of recessive cardiomyopathies has major implications for diagnosis and screening, particularly in underrepresented populations, such as those of the Middle East.