Limb-girdle muscular dystrophy- type 2B
Overview
The earliest descriptions of limb-girdle weakness are ascribed to Leyden and Möbius in 1876 and 1879, respectively. They described adult patients with a pelvic and femoral distribution of weakness and atrophy with a benign course. In 1884, Erb characterized a juvenile form of proximal muscle weakness. Erb's patient had only shoulder-girdle weakness and atrophy, with sparing of other muscles of the body and a benign disease course compared with that described by Duchenne in the 1860s. Duchenne, a French physician, initially described a condition of progressive lethal wasting of degenerative skeletal muscle, which was later referred to as Duchenne muscular dystrophy. At that time, the differentiation between the spinal muscular atrophies and weakness associated with central nervous system disorders and primary muscle disease had not been established.
Symptoms
Bashir et al. (1994) reported 2 unrelated consanguineous families, 1 of Palestinian and 1 of Sicilian origin, with autosomal recessive LGMD. Age at onset ranged from 15 to 25 years with difficulty in climbing stairs, fatigue, weakness, and markedly elevated serum creatine kinase. EMG showed myopathic changes and skeletal muscle biopsies showed severe myopathic changes with variation of fiber size, fiber splitting, increased connective tissue, and some necrotic changes. Disease progression was relatively slow.
Causes
LGMD2B is also a common cause of autosomal recessive LGMD, accounting for about 20% of cases in the Brazilian population. However, in some populations (eg, Cajun, Arcadian groups), it accounts for about 40% of cases.