MYH11 ‐Related Hereditary Type 2 Visceral Myopathy in a Large Kindred: Diagnostic Odyssey With Milder Clinical Manifestations

ABSTRACT

MYH11 ‐related hereditary type 2 visceral myopathy is a rare smooth muscle disorder typically presenting in infancy with severe gastrointestinal and genitourinary dysfunction. We describe a 73‐year‐old female with lifelong symptoms of gastrointestinal and urinary dysfunction, including chronic constipation, neurogenic bladder, recurrent urinary tract infections, gastroparesis, and pelvic organ prolapse. A multigenerational family history revealed similar visceral smooth muscle abnormalities among 14 affected individuals over five generations, suggesting autosomal dominant inheritance. Whole‐genome sequencing identified a heterozygous, likely pathogenic variant in MYH11 c.5819del; p.(Pro1940HisfsTer91), consistent with the diagnosis of autosomal dominant type 2 visceral myopathy. This variant causes production of an abnormally elongated myosin‐heavy chain, disrupting muscle contractile function. This individual's survival into her eighth decade reflects long‐term clinical stability, possibly attributable to the variant's milder effect. We describe the clinical course of the disease, along with a comprehensive review of previously described individuals with the same variant. This case broadens the phenotypic spectrum of MYH11 ‐associated visceral myopathy, demonstrating that late‐onset, milder forms can occur and remain compatible with long‐term survival with optimal supportive management. Comprehensive genetic evaluation identifies primary disorders, enabling precise diagnosis, tailored management, and informed genetic counseling for complex phenotypes.