High recurrence of recombinants in a family with pericentric inversion of chromosome 18.

We report a family in which the father carries a pericentric inversion involving two third of the chromosome 18 (p11.2q22). Of his three children, the proposita and her youngest brother show partial duplication of the short arm and partial deficiency of the long arm; the oldest sister shows the other recombinant (partial duplication of the long arm and partial deficiency of the short arm). In the literature, we found only one family in which both recombinants of a parental pericentric inversion were present in the same offspring and none with three affected and both kinds of recombinants. A review of the reported familial cases reveals that the risk of aneusomy of recombination, at least for chromosome-18 inversion carriers, may be close to 20% and no only 5-10% as previously reported.