SEGREGATION OF A FAMILIAL BALANCED (12-10) INSERTION RESULTING IN DUP(10)(Q21.2Q22.1) AND DEL(10)(Q21.2Q22.1) IN FIRST COUSINS

An interchromosomal insertion in 3 generations of a family was ascerta ined through two developmentally delayed first cousins. Cytogenetic an alysis using G-banding and chromosome painting showed an apparently ba lanced direct insertion of chromosome 10 material into chromosome 12, ins(12;10)(q15; q21.2q22.1), in the mothers and grandfather of these c hildren, The proposita inherited only the derivative 10 chromosome, re sulting in deletion of 10q21.2 --> 22.1 while her cousin inherited onl y the derivative 12, resulting in duplication of 10q21.2 --> 22.1. A c omparison of the proposita with published deletion cases suggests a pa ttern of anomalies attributable to deletion of the 10q21 --> q22 regio n: developmental delay hypotonia, a heart murmur, telecanthus, broad n asal root and ear abnormalities. This is the first report of a nontand em duplication of the 10q21 --> q22 region. The phenotype of the cousi n with the duplication does not overlap greatly with published tandem 10q duplications. Finally, this report reaffirms the importance of obt aining family studies of patients with interstitial chromosomal abnorm alities. (C) 1997 Wiley-Liss, Inc.