Duplication-deficiency of chromosome 18, resulting from recombination of a paternal pericentric invesion, with a note for genetic counselling.

A fifth case of rec(18) resulting from recombination of a paternal pericentric inversion is described. The propositus' complement includes a chromosome 18 with partial deletion of the long arm, and partial duplication of the short. The recombination risk is evaluated at 5%. The eventuality of deleterious effects of pericentric inversions is discussed.