Duchenne Muscular Dystrophy is a disease of-

Ans. is 'b' i.e., Sarcolemmal protein DUCHENNE MUSCULAR DYSTROPHY : (PSEUDOHYPEROPHIC MUSCULAR DYSTROPHY) o Duchenne muscular dystrophy is the most common hereditary neuromuscular disease affecting all races and ethnic groups. o Inheritance : X linked recessive o Presentation occurs between ages 3 and 5 Pathogenesis o Duchenne muscular dystrophy is caused by a mutation in the gene responsible for producing dystrophin. o Dystrophin is `subsarcolemmal protein' localized to the inner surface of the sarcolemma of the muscle fibre. o Dystrophin is pa of Dystrophin - Glycoprotein sarcolemmal complex and this protein deficiency leads to secondary loss of sarcoglycans and dystroglycans resulting in weakness of sarcolemma, causing membrane tears and muscle fiber necrosis. Clinical manifestations: o Gower's sign is positive o Pseudohyperophy of calf is seen (muscle is replaced by fat & connective tissue) o Loss of muscle strength is progressive. o Proximal muscles and neck flexors are involved more o Leg involvement is more severe than arm involvement. o Contractures of heel cords and iliotibial band occurs (by age of 6 years) o progressive scoliosis develops.