Complex chromosome rearrangements involving chromosomes 1;3 and 2;3 in two abnormal children.

Complex chromosome rearrangements (CCR) involving multiple breaks in two chromosomes are rare. The detection of a four-break apparently balanced rearrangement involving chromosomes 1 and 3 in a child with developmental delay led us to reanalyse, using prometaphase banding, another complex two-chromosome rearrangement in a previously reported case (Fitzgerald 1974). The relationship between clinical abnormalities and apparently balanced rearrangements is discussed.