Duplication of (2)(q11.1-q13.2) in a boy with mental retardation and cleft lip and palate: another clefting gene locus on proximal 2q?

A 4-year-old boy with left cleft lip and cleft palate, multiple minor anomalies and developmental delay revealed an abnormal chromosome 2 with enlarged proximal long arm, de novo, in his karyotype. Fluorescence in situ hybridization with a chromosome 2 library and band-specific YACs confined the duplicated segment to 2q11.1-q13.2 and indicated a direct tandem duplication due to unbalanced crossover between chromatids.