We describe a 12-year-old girl with congenital myopathy. ATPase histochemical reactions
and immunocytochemical analysis of muscle fiber-type composition with monoclonal antibodies
against slow, fast (2 A and 2 B) and fetal myosin demonstrate that this congenital
disease is characterized by type 2 A muscle fiber uniformity and smallness. This is
an unusual feature for a congenital myopathy in which the fiber type predominance,
when present, is confined to type I.
Congenital myopathies - Type 2 A fibers - Myosin
