Trisomy 16q23----qter arising from a maternal t(13;16)(p12;q23): case report and evidence of the reciprocal balanced maternal rearrangement by the Ag-NOR technique.

We describe a female new-born with partial trisomy of the long arm of chromosome 16. The chromosome anomaly was the result of an unbalanced segregation of a maternal translocation t(13;16)(p12;q23). Dynamic (RBG, GBG) banding and the Ag-NOR technique ascertained the reciprocal balanced maternal translocation between the 16q23----qter and 13q12----pter segments because nucleolar organizers were present on the tip of long arms of the derivative 16 maternal chromosome. As monosomy 13p has little or no deleterious effect we consider our case as exhibiting the phenotype of trisomy 16q23----qter free from any monosomic feature. Clinical effects are of less consequence as compared with previously published cases of partial trisomy 16q.