Qualitative or quantitative defects of filamin C

Qualitative or quantitative defects of filamin C (FLNC) refer to a group of rare genetic disorders caused by mutations in the FLNC gene, which encodes filamin C, a large cytoskeletal protein critically important for the structural integrity of muscle cells. Filamin C is predominantly expressed in skeletal and cardiac muscle, where it crosslinks actin filaments and connects the sarcomere to the cell membrane. Defects in this protein lead to a spectrum of myofibrillar myopathies and cardiomyopathies. These conditions are sometimes referred to as filaminopathy or FLNC-related myofibrillar myopathy. Clinical manifestations primarily affect the skeletal and cardiac muscle systems. Patients may present with progressive proximal and distal muscle weakness, exercise intolerance, respiratory insufficiency, and cardiomyopathy — including hypertrophic cardiomyopathy, dilated cardiomyopathy, and restrictive cardiomyopathy. Cardiac involvement can lead to arrhythmias and sudden cardiac death, which represents one of the most serious complications. Muscle biopsies typically show characteristic myofibrillar disorganization with protein aggregates. The age of onset is variable but most commonly presents in adulthood, though earlier presentations have been reported. There is currently no curative treatment for FLNC-related disorders. Management is supportive and multidisciplinary, focusing on cardiac surveillance with regular echocardiography and electrocardiography, treatment of heart failure and arrhythmias (including consideration of implantable cardioverter-defibrillators in high-risk patients), physical therapy for skeletal muscle weakness, and respiratory support when needed. Genetic counseling is recommended for affected families.

Common questions about Qualitative or quantitative defects of filamin C