Characterized by a congenital, nonprogressive
myopathy secondary to (proved histologically and electron microscopically)
Multicore myopathy, severe mental retardation, radiologic evidence of
pituitary gland hypoplasia with short stature, hypogonadotropic
hypogonadism, and generalized hypotrichosis. Musculoskeletal anomalies may
include delayed bone maturation, osteopenia, lumbar hyperlordosis, limited
joint mobility (particularly of the big joints, e.g., shoulders, elbows, hips, knees,
ankles), clinodactyly, and evidence of mild but generalized muscle weakness.
Facial anomalies may include microcephaly, thickening of the skull,
hemifacial microsomia, enlarged frontal sinuses, microtia, atretic ear
canal, hypertelorism, blepharoptosis, myopia, limited sagittal eye
movements, high arched palate, and facial muscle weakness. Muscle biopsies
reveal a high degree of variation in fiber size and occasionally fiber
splitting. The multicores consist of numerous circumscribed, small areas of
disorganization of the myofibrillar structure and decreased oxidative enzyme
activity secondary to a lack of mitochondria. The long axis of the lesion is
perpendicular or parallel to the long axis of the muscle fiber. These cores
are usually smaller than central cores. For this reason they are also called
minicores.