De novo inverted duplication 9p21pter involving telomeric repeated sequences

We report on clinical and cytogenetic findings in a boy with partial 9p dup lication, dup(g)(p21pter), Clinical manifestations included facial and hand anomalies and mental retardation. Fluorescence in situ hybridization (FISH ) and comparative genomic hybridization (CGH) were used to characterize fur ther and confirm the conventional banding data. Investigation by FISH using whole chromosome 9 paint probe showed that the additional material was der ived from chromosome 9, Using CGH, a region of gain was found in the chromo some segment 9p21pter, YACs and telomeric probes confirmed the duplicated r egion, Using the all-human telomeric sequences probe, intrachromosomal telo meric signal was noted on the short arm of the abnormal chromosome 9, Mecha nism of formation of the duplication, including intrachromosomal telomeric sequences, is discussed. Am. J, Med, Genet, 83:125-131, 1999, (C) 1999 Wile y-Liss, Inc.