Which of the following is not characteristic of congenital muscular dystrophies?
ExplanationC. The congenital muscular dystrophies are a group of disorders mostly inherited in an autosomal recessive fashion. In utero, there may be decreased movements. At birth, these children are hypotonic and weak, presenting with arthrogryposis, and may develop respiratory insufficiency and bulbar dysfunction. With time they may develop contractures and scoliosis. These patients also have developmental delay and developmental anomalies of the cerebral cortex. As a consequence of cortical involvement, seizures occur in some subtypes of these disorders. Creatine kinase is markedly elevated. EMG shows myopathic changes. Histopathologically, there are dystrophic changes with degeneration and regeneration of muscle fibers, and infiltration of connective tissue. The congenital muscular dystrophies are caused by genetic defects in sarcolemmal membrane proteins or membrane-supporting structures.
