Split centromeric alpha-satellite FISH signals in a whole arm translocation 5p;10p: consequences and implications for interphase FISH studies

This is a case report of an apparently balanced whole arm translocation between the short arms of chromosomes 5 and 10 in which the centromeric alpha-satellite DNA is split between both derivative chromosomes for both probes, leading to abnormal signal patterns. The patient requested preimplantation genetic testing for the unbalanced products of the translocation. However, using centromeric alpha-satellite DNA probes as controls for the subtelomeric-specific probes in interphase was not informative because of the split signals. The ramifications of such variation in the alpha-satellite regions of chromosomes for other interphase FISH tests are discussed.