Natural History and Phenotypic Spectrum of Myofibrillar Myopathies and Myopathies Associated With MFM-Related Genes

BACKGROUND AND OBJECTIVES: Myofibrillar myopathy (MFM) is a pathologically defined but genetically heterogeneous myopathy; however, myofibrillar pathology may be absent in some patients with pathogenic variants in MFM-related genes. The natural history of MFM and myopathies associated with MFM-related genes remains poorly characterized. METHODS: We retrospectively reviewed patients evaluated at Mayo Clinic (January 1993-March 2024) with either pathologically confirmed MFM or myopathies associated with MFM-related genes. Patients without genetic testing or skeletal muscular manifestations were excluded. RESULTS: = 1.000). DISCUSSION: MFM and myopathies associated with MFM-related genes are clinically heterogeneous, with desminopathy showing earlier cardiac manifestations and gait aid requirement and more frequent cardiopulmonary involvement. Given the phenotypic variability, genetic diagnosis is crucial for patient management and prognosis.