Molecular cytogenetic characterization of a prenatally detected supernumerary minute marker chromosome 8

The characterization of a prenatally detected very small (approximately hal f of 18p-(karyotype: 47,XX, +mar[16]/46,XX[7]) supernumerary marker chromos ome (SMC) identified by GTG-banding analysis is described. The marker has b een identified as derived from chromosome 8 centromeric material using a co mbination of different cytogenetic (GTG-, NOR-, CBG banding), molecular cyt ogenetic (24 colour-fluorescent in situ hybridization [FISH], three-colour FISH using centromeric probes for all human chromosomes) and molecular gene tic techniques (microsatellite analysis). This is the first case described with such a minute SMC derived from chromosome 8 diagnosed prenatally, the 15th case reporting on a SMC originating from chromosome 8 and the third su ch case without any severe clinical features. Copyright (C) 1999 John Wiley & Sons, Ltd.