Molecular cytogenetic characterization and origin of two de novo duplication 9p cases

We report on two additional cases with duplication of 9p, minor with facial anomalies and developmental delay. Using fluorescence in situ hybridizatio n and single-copy probes, we showed that the first case was a direct duplic ation, whereas the second case was inverted. The extent of the direct dupli cation was defined as 9p12 --> p24 by microdissection and microcloning of t he aberrant chromosome and subsequent chromosome-specific comparative genom ic hybridization. DNA polymorphism analysis with eight microsatellite marke rs revealed that the origin of the dup(9p) was maternal; in the first case, whereas it was paternal in the second. (C) 2000 Wiley-Liss, Inc.