Molecular cytogenetic characterisation of partial trisomy 9q in a case with pyloric stenosis and a review

Partial trisomy 9q represents a rare and heterogeneous group of chromosomal aberrations characterised by various clinical features including pyloric s tenosis. Here, we describe the case of a 1 year old female patient with dif ferent dysmorphic features including pyloric stenosis and prenatally detect ed partial trisomy 9q. This partial trisomy 9q has been analysed in detail to determine the size of the duplication and to characterise the chromosoma l breakpoints. According to the data gained by different molecular cytogene tic techniques, such as fluorescence in situ hybridisation (FISH) with whol e and partial chromosome painting probes, yeast artificial chromosome (YAC) probes, and comparative genomic hybridisation (CGH), the derivative chromo some 9 can be described as dup(9) (pter->q22.1::q31.1->q22.1::q31.1-> q22.1 ::q31.1->qter). Four breakpoint spanning YACs have been identified (y806f02 , y906g6, y945f5, and y747b3) for the proximal breakpoint. According to thi s new case and previously published data, the recently postulated putative critical region for pyloric stenosis can be narrowed down to the subbands 9 q22.1-q31.1 and is the result of either partial trisomy of gene(s) located in this region or a gene disrupted in 9q31.