Parental origin of apparently balanced de novo complex chromosomal rearrangements investigated by microdissection, whole genome amplification, and microsatellite-mediated haplotype analysis.

Complex chromosomal rearrangements (CCRs) are rare findings in clinical cytogenetics. As a result of the high risk of unbalanced segregation, familial cases are even rarer and maternal transmission occurs more frequently than paternal transmission. Analogous to Drosophila and mice, as well as to CCRs involving the Y chromosome or a clinically relevant associated deletion, a preferential origin in spermatogenesis has been assumed but not proven directly and systematically thus far. Here, we investigated three healthy adults, one healthy child, and one child with multiple congenital anomalies and various balanced de novo CCRs. The analyses were performed in each case on 10 copies of a derivative chromosome and their normal homologs by glass-needle microdissection, whole genome amplification (WGA), and microsatellite-mediated haplotype analysis. With respect to the number of chromosomes involved in each case and in all cases together, the number of chromosomal segments in each case and in all cases together, and the number of breakpoints in each case and in all cases together, the conformity for paternal origin of all derivative chromosomes and maternal origin of their normal homologs makes formation in paternal germline more likely than a postzygotic formation with an accidental uniformity. In conclusion, our results confirm the preferential formation of de novo balanced CCRs in the paternal germline.