Fingerprint body myopathy: a report of twins.

Ultramicroscopic changes of subsarcolemmal fingerprints in the muscle of children with infantile hypotonia and weakness may represent a specific congenital entity. Four children have been reported so far. The two children reported in the present paper are the first full siblings to be described and, in addition, are identical twins. Four of these six children also had mental retardation, which suggests that this disorder may carry with it a significant risk of central nervous system abnormality.