Whole exome sequencing identified a novel LAMA2 frameshift variant causing merosin-deficient congenital muscular dystrophy in a patient with cardiomyopathy, and autism-like behavior

Abstract

Muscular dystrophy (MD) is a group of multiple muscle diseases, which causes severely impaired motor ability, degeneration and dysfunctions in the musculoskeletal system, respiratory failure and feeding difficulties. LAMA2-related MD is caused by pathogenic variants in the LAMA2 gene, encoding laminin a2 chain, a component of the skeletal muscle extracellular matrix protein laminin-α2β1γ1. We performed clinical examination and molecular genetic analysis in a patient with congenital MD (CMD), and autism-like phenotype. We performed whole exome sequencing (WES) to find possible genetic etiology of CMD in an Iranian non-consanguineous patient. The pathogenicity of the variants was assessed using various Bioinformatics tools. American College of Medical Genetics and Genomics (ACMG) guidelines were used to interpret the variant and Sanger sequencing in the patient and her family was applied for the confirmation of the variant. WES results showed a novel frameshift homozygous variant (p.Tyr1313LeufsTer4) in the LAMA2 gene leading to the CMD phenotype. This variant resides in a highly conserved region and was found to be co-segregating in the family. It fulfils the criteria of being pathogenic. We successfully identified a novel LAMA2 pathogenic variant in an Iranian patient suffering from CMD and autism using WES. Identification of disease-causing variant in autosomal recessive disorders such as CMD can be useful in genetic counseling, prenatal diagnosis, and predicting prognosis of the disease.