Familial pericentric inversion (13) detected by antenatal diagnosis.

A recombinant rec (13), dup q chromosome was diagnosed in a 17-week fetus following amniocentesis. Subsequently, a familial pericentric inversion of chromosome 13 was seen to be segregating in the family and the same recombinant 13 was present in a mentally retarded aunt of the fetus. The clinical features of the carriers of the inversion product are discussed with reference to previous cases.