Partial trisomy for 5q and monosomy for 12p in a liveborn child as a result of a complex five breakpoint chromosome rearrangement in a parent.

A balanced complex chromosome rearrangement (CCR) involving four chromosomes is very rare and may lead to different types of aneuploid germ cells. We report a liveborn child with multiple congenital anomalies and an apparently balanced translocation, t(11;12). High resolution chromosome analysis in the mother showed a CCR involving chromosomes 5, 11, 12, and 16. In situ hybridisation showed that this CCR was the result of a five break rearrangement, and that the derivative chromosome 12 consisted of parts of chromosomes 5, 11, and 12. From this it could be deduced that the karyotype of the child was not balanced, but resulted in partial trisomy for 5q and partial monosomy for 12p. The clinical findings in the child were compatible with partial trisomy for 5q.