Clinical meaning
Duchenne muscular dystrophy results from mutations in the DMD gene on Xp21, the largest known human gene encoding the protein dystrophin. Dystrophin functions as a structural bridge between the intracellular actin cytoskeleton and the extracellular matrix via the dystrophin-associated glycoprotein complex (DAGC). Without dystrophin, the sarcolemma loses mechanical stability during muscle contraction, allowing calcium influx that activates proteases and triggers necrosis. Ongoing cycles of necrosis overwhelm satellite cell-mediated regeneration, leading to progressive fibrosis and fatty replacement. The nurse manages multi-system complications including respiratory decline, cardiomyopathy screening, mobility preservation, nutritional optimization, and psychosocial support for the child and family.
Exam relevance
Risk factors: - X-linked recessive inheritance (affects almost exclusively males) - Maternal carrier status (carrier mothers transmit the gene to 50% of sons) - Spontaneous mutations account for approximately one-third of cases - Family history of neuromuscular disease - Delayed motor milestones in early childhood