Prenatal detection of pericentric inversion of chromosome 12.

A pericentric inversion of chromosome 12 was detected in an unborn baby by a second-trimester amniocentesis for prenatal diagnosis because of advanced maternal age. Subsequently, the identical pericentric inversion was found in the phenotypically normal father and a sibling. In this case of familial pericentric inversion, the parents were assured that their unborn baby was anticipated to be normal. The importance of banding studies for precise identification of structurally abnormal chromosomes and the need for chromosome study of family members for the peroper counseling of prenatal diagnosis of such a variant chromosome are discussed.