Complementary duplication and deletion of 17 (pcen----p11.2): a family with a supernumerary chromosome comprised of an interstitially deleted segment.

A sister and brother were investigated because both were developmentally delayed although they had somewhat different physical anomalies. The girl was found to have an interstitial deletion of chromosome 17. Her karyotype was 46,XX,del(17) (pter----p11.2::cen----qter). Her brother had normal chromosomes in peripheral lymphocytes. Cytogenetic investigation of the mother showed the presence of the same deletion as in her daughter and a small supernumerary chromosome. The supernumerary chromosome appeared to contain the material deleted from the short arm of 17 since the mother's phenotype was normal. Study of skin fibroblasts in her son showed that he was mosaic for a normal cell line and one that contained the extra small chromosome; thus, he had mosaic partial trisomy 17(cen----p11.2). The origin of the centromere and telomere(s) of the small supernumerary chromosome in this family presents an interesting problem.