Next-generation sequencing identifies a homozygous mutation in ACADVL associated with pediatric familial dilated cardiomyopathy

S.J. Carlus, I.S. Almuzaini, M. Karthikeyan, L. Loganathan, G.S. Al-Harbi, A.M. Abdallah, K.M. Al-Harbi

Pediatrics Department, Cardiogenetics Unit, College of Medicine, Taibah University, Al-Madinah, Kingdom of Saudi Arabia. justincarlus@gmail.com

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• Cardiology

OBJECTIVE: Pediatric familial dilated cardiomyopathy (DCM) is a rare and severe heart disease. The genetics of familial DCM are complex and include over 100 known disease-causing genes, but many causative genes are unknown. We aimed to identify the causative gene for DCM in a consanguineous Saudi Arabian family with affected family members and a history of sudden death.

PATIENTS AND METHODS: Affected (two children) and unaffected (one sibling and the mother) family members were screened by next-generation sequencing (NGS) for 181 candidate DCM genes and underwent metabolic screening. Fifty-seven clinically annotated controls and 46 DCM cases were then tested for the identified mutation. In silico structural and functional analyses including protein modeling, structure prediction and dynamic simulations were performed.

RESULTS: A homozygous missense mutation in exon 15 of the acyl-CoA dehydrogenase very long chain gene (ACADVL; chr17:7127303; G>A) was identified in affected subjects that substituted histidine for arginine at codon 450 (p.R450H). The variant was heterozygous in the mother and unaffected sister. The mutation was absent in 57 clinically annotated controls and 48 pediatric DCM cases. The mutation was predicted to cause a significant and deleterious change in the ACADVL protein structure that affected drug binding, stability, and conformation. Metabolic screening confirmed VLCAD deficiency in affected individuals.

CONCLUSIONS: The ACADVL R450H mutation is an uncommon cause of the DCM phenotype that appears to be autosomal recessive. Targeted NGS is useful for identifying the causative mutation(s) in familial DCM of unknown genetic cause.

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