Duplication 12q mosaicism in two unrelated patients with a similar syndrome.

Two unrelated children with a similar syndrome were found to have mosaicism for a cell line containing one chromosome 12 with an additional faintly G-banding staining region that apparently represents a duplication of the distal portion of the long arm. The homology and the other chromosomes are normal, as are the parental chromosomes. The remarkable phenotypic similarity of the 2 patients and their resemblance to 2 previously reported patients with duplication of the same chromosome region suggests that duplication 12q24 results in a clinically identifiable malformation syndrome.