 The loss of protein dystrophin ultimately leads to a lethal syndrome of skeletal and cardiac myopathy, stationary night blindness, mental retardation, a cardiac-conduction defect, and a subtle smooth-muscle defect.Some of these traits are also found in a subset of the limb-girdle muscular dystrophies that result from sarcoglycan defects.α-Dystrobrevin proteins were found absent in a heart that is highly susceptible to injury during cardiac stress.