Satellite III sequences on 14p and their relevance to Robertsonian translocation formation.

Robertsonian translocations (ROBs) are the most common rearrangements in humans, contributing significantly to genetic imbalance, fetal wastage, mental retardation and birth defects. Rob(14q21q) and rob(13q14q), which are formed predominantly during female meiosis, comprise the majority (approximately 85%) of all ROBs. Previous studies have shown that the breakpoints are consistently located within specific regions of the proximal short arms of chromosomes 13, 14, and 21. The high prevalence of these translocations, the consistent breakpoints found, and the fact that roughly 50% of cases occur sporadically suggest that the sequences at or near the breakpoints confer susceptibility to chromosome rearrangement and that the rearrangements occur through a specific mechanism. To investigate this hypothesis, we developed hamster-human somatic cell hybrids derived from de novo rob(14q21q) patients that contained the translocated chromosome segregated from the other acrocentric chromosomes. We determined the physical order of five satellite III subfamilies on 14p, and investigated their involvement in formation of these de novo translocations.