Preimplantation diagnosis of early-onset Alzheimer's disease 19/3/02. By the Public Health Genetics Unit First use of preimplantation genetic diagnosis to select an embryo without an early-onset Alzheimer's mutation.

A team at the Reproductive Genetics Institute in Chicago has reported the first use of preimplantation genetic diagnosis to enable a woman who knows she is highly likely to develop a single-gene form of early-onset Alzheimer's disease to select an embryo that does not carry the causative mutation.

The woman is a member of a family affected by early-onset Alzheimer's disease and, although currently asymptomatic, she has had a genetic test that shows she carries a highly penetrant mutation in the gene encoding the amyloid precursor protein.

Both oocytes tested in the first IVF cycle were found to be affected. In the second cycle, four unaffected embryos were obtained and transfer of all four of these resulted in a singleton pregancy. Chorionic villus sampling confirmed that the fetus did not carry the mutation, and a healthy baby was born.

Alzheimer’s disease is a degenerative disease that slowly and progressively destroys brain cells.

PHGU comment

Considerable controversy surrounds this use of preimplantation genetic diagnosis. The issue is whether a woman who knows that she is likely to fall victim to dementia while still in her 30s, and so be unable to care for her child, has the right to choose to become a mother.

In fact this moral question would be the same if the woman had become pregnant naturally and used prenatal diagnosis with selective abortion to avoid the birth of an affected child, but the use of the relatively new technology of PGD has brought the issue more firmly into the public view. An accompanying commentary marshals some strong arguments to suggest that reproductive freedom should not be absolute, but continuing ethical debate about this issue seems certain.

Article courtesy of the Public Health Genetics Unit .

Photo credit: K. Hardy

Further reading

Verlinsky Y et al. Preimplantation diagnosis for early-onset Alzheimer disease caused by V717L mutation. JAMA 2002287: 1018-1021. Abstract ; Full text