Dorsal skin and fingernails on the volar aspect of the hand: an unusual anatomic deformity.

A very unusual hand malformation is reported in which dorsal skin and nails exist on the volar aspect of the hands. This patient also exhibits mental retardation and microcephaly as well as a partial deletion of chromosome 6. Fifty percent of a small series of patients previously reviewed who presented with chromosome 6 abnormalities demonstrated abnormalities of the hands. Unusual deformities of the hands associated with mental retardation and microcephaly may be related to an abnormality of chromosome 6.