Duplication of 11p14.3-p15.1 in a mentally retarded proband and his mother detected by G-banding and confirmed by high-resolution CGH and BAC FISH.

A 10-year-old African-American male has been followed since 2 years of age due to his mental retardation, severe behavioral problems, and dysmorphism. Conventional cytogenetic analysis, chromosome painting, high-resolution comparative genomic hybridization (HR-CGH), and bacterial artificial chromosome fluorescent in situ hybridization (BAC FISH) revealed an apparent duplication in the short arm of a chromosome 11, dup(11)(p14.3p15.1), seen also in his mentally retarded mother. The proband had moderate to severe mental retardation, a history of IUGR, infantile hypotonia, FTT, exotropia, inguinal hernia repair, and several dysmorphic features. His mother had mild mental retardation, a history of impulsivity, assaultive outbursts, and similar dysmorphism. Although G-banding and FISH indicated a duplication, HR-CGH confined the localization of material to bands 11p14-11p15 and aided the selection of locus-specific BAC clones to more precisely characterize the duplicated region. To our knowledge, the results represent the first example of a familial, cytogenetically visible duplication of euchromatin in 11p that excludes the Beckwith-Wiedemann syndrome critical region. It is possible that one or more genes had been disrupted at the breakpoints of the above structural chromosomal rearrangement giving rise to the present phenotype.