Unilateral radial aplasia and trisomy 22 mosaicism.

A child with unilateral radial aplasia, asymmetry, other malformations, and severe physical and mental retardation is reported. In blood and bone marrow cultures a low mosaicism for trisomy 22 was found. In a few cells a chromosome 22 was missing. The importance of early cytogenetic analysis on large numbers of cells is emphasised, especially in cases of asymmetry where mosaicism is suspected.