Duchenne Muscular Dystrophy is a disease of (LQ)
|C||Muscle contractile proteins|
|D||Disuse atrophy due to muscle weakness|
DUCHENNE MUSCULAE DYSTROPHY: (PSEUDOHYPERTROPHIC MUSCULARDYSTROPHY)
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 [disorder does not present at birth or in infancy]
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 part 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.
o Gower's sign is positive
o Pseudohypertrophy 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.
Chest deformity (scoliosis): Impairs pulmonary function
By age of 16 and 18 years patients are predisposed to serious pulmonary fatal infections.
Cardiac: Cardiomyopathy and CHF may be seen
Cardiac cause of death is uncommon
Intellectual impairment: is common (IQ is one SD below the mean)