Early onset autosomal dominant myopathy with rigidity of the spine: A possible role for laminin beta 1?

We describe 17 individuals from seven families with a slowly progressive, early onset, autosomal dominant myopathy with proximal muscle weakness, calf hypertrophy, contractures, spinal rigidity and, in five of the adult cases, a cardiac conduction defect. A deficiency of the laminin pi chain of the skeletal muscle fibres was found in the older individuals of these families, but not the younger members. Other laminin chains, dystrophin and the dystrophin-associated glycoproteins were normal. The age-related deficiency of the laminin beta 1 is restricted to the skeletal muscle fibres and not the vascular tissue, suggesting that this may be a secondary phenomenon. These findings suggest that a laminin or a laminin-binding protein is implicated in some forms of dominant limb girdle myopathies. (C) 1997 Elsevier Science B.V.