Scientists have discovered a gene carried only by women that may increase the risk of late onset Alzheimer’s. The findings by the scientists at the Mayo Clinic College of Medicine were published in the journal Nature Genetics, and are the first evidence to suggest that genetics may partly explain why more women than men develop the disease. The key gene variant was found on the X chromosome of which females have two copies, compared to only one in males. Although the cause of Alzheimer’s is unknown, a mixture of environmental and genetic factors are believed to be involved. Nearly twice as many women than men develop the disease.