Congenital myopathy 7A, myosin storage, autosomal dominant
OMIM number: 608358
Comments closing date: 18/11/2025
Autosomal dominant myosin storage congenital myopathy-7A (CMYO7A) is a rare inherited muscle disorder caused by mutations in the MYH7 gene on chromosome 14. This gene encodes cardiac beta-myosin heavy chain, a protein essential for muscle contraction. Faulty versions of this protein accumulate in slow-twitch muscle fibres, forming clumps that disrupt muscle function. Symptoms often begin in childhood but may appear later. Affected individuals may walk with a waddling gait, have delayed motor milestones, and struggle with activities like climbing stairs or lifting their arms. In some cases, breathing muscles may also be affected. The MYH7 gene is also linked to other conditions with overlapping features, including autosomal recessive myosin storage congenital myopathy-7B (OMIM 255160), Laing distal myopathy (OMIM 160500), dilated cardiomyopathy 1S and left ventricular noncompaction 5 (OMIM 613426), and hypertrophic cardiomyopathy 1 (OMIM 192600), which already has an HFEA licence. Although the exact mechanism of muscle weakness remains unclear, the presence of protein clumps in muscle fibres is a hallmark of CMYO7A
