Origin of a paternal (13q;15q) translocation leading to dup(13q) in two half sibs.

We report on two half-sibs, a male and a female with dup(13)(q1405 leads to qter) that resulted from a der(15),t(13;15)(15qter leads to 15q25::13q1405 leads to 13qter), h+, pat. Their manifestations were similar to those with duplication of the distal half 13q. The father was a balanced de novo translocation carrier. Since the der(15) had a long secondary constriction, it was possible to trace the site of the mutation to the germ cell of the patients paternal grandmother who had this distinctive long secondary constriction in one of her normal 15 chromosomes.