[Congenital myopathy with type 2 fiber hypoplasia]. / Kongenitální myopatie s hypoplazií vláken 2. typu.

An atypical case of congenital myopathy characterised by a low frequency of hypoplastic type 2A fibres, type 2B fibre deficiency and type 1 fibre predominance is reported. Our patients are siblings, a 10 year old girl and a 7 year old boy. Both children suffered from ophthalmoplegia and muscle weakness, and the boy also showed signs of psychomotoric retardation. A muscle biopsy from musculus trapezius has shown type 1 fibre predominance and hypoplastic type 2 fibres.