Faulty gene may cause Alzheimer's in women

Medicine A faulty gene on the female X chromosome may contribute to the development of Alzheimer's disease in women, scientists said yesterday.

The discovery is the first evidence of a sex-specific risk factor for the disease. Scientists identified a variant in the gene PCDH11X that significantly correlated with susceptibility to late-onset Alzheimer's disease (Load).

When the data was analysed to account for sex, the association was found to be almost entirely confined to women. PCDH11X lies on the female X chromosome, one of the "packages" of DNA inside the cell nucleus.

It provides the coded building instructions for a protein called protocadherin.

There is evidence that protocadherins may be affected by an enzyme linked to early-onset forms of Alzheimer's. Dr Steven Younkin of the Mayo Clinic College of Medicine in Jacksonville, Florida, led the research, reported in the Nature Genetics. The researchers wrote: "Further study should open new therapeutic possibilities for this devastating disease."