Genetic prenatal and preimplantation diagnosis of trinucleotide repeat disorders

This review examines the history, present status and future of genetic antenatal diagnosis for the trinucleotide repeat disorders, including Huntington's disease, Fragile X syndrome and myotonic dystrophy. Conventional prenatal diagnosis and the relatively new field of preimplantation genetic diagnosis, which can diagnose an affected embryo before a pregnancy is established, are described. Genetic diagnosis for these late onset diseases has inherent difficulties and many controversies. However, antenatal diagnosis is an important service for an individual with one of these mutations, who wishes to prevent the birth of an affected child.