"We and other investigators have found evidence that estrogen helps protect women from developing Parkinson's," says Walter Rocca, M.D., M.P.H., Mayo Clinic neurologist and epidemiologist, and lead study investigator. "So, a gene variant that would decrease estrogen production or activity would put those women at greater risk for the disease."
The study associated variants in the following three genes with development of Parkinson's: estrogen receptor 1 gene (ESR1); estrogen receptor 2 gene (ESR2); and PR domain-containing protein 2 gene (PRDM2).
"The gene variants are not a defect or a problem in and of themselves -- they are part of human differences, simply differences across people, like being slim, short or blue-eyed," says Dr. Rocca. "These differences make one subgroup of the population more susceptible to a disease like Parkinson's. However, sometimes the genetic variant is a weak risk factor, and the disease only manifests if another risk factor is present, such as a particular diet, physical exercise, taking certain medications or a medical event."
The study was conducted using a database from a previous study of the entire human genome for genes linked to Parkinson's. For the new study, the Mayo Clinic investigators examined several genes for variants in 172 women who had Parkinson's and 229 women who did not have the disease.
Dr. Rocca explains that some genetic variants the study pinpointed for association with Parkinson's are quite common, affecting 10 to 20 percent of the female population. As women are not routinely tested for these gene variations, however, those affected would be unaware, he says.
"If the findings of this study are replicated and confirmed, the hope is to use these variants to predict the risk of disease using a simple blood test," says Dr. Rocca. He explains that the test would be particularly useful for women and their physicians before deciding to conduct an elective ovariectomy, surgical removal of the ovaries, because a combination of estrogen-reducing factors could amplify a woman's risk for Parkinson's.
mayoclinic
Patients who were classified as alcohol or tobacco users, defined as those who had smoked or drank alcohol in the previous year, developed cancer at a younger age than non-drinkers and non-smokers. Current alcohol and tobacco users developed cancer an average of 7.8 years earlier (age 63.2 years in women and 62.1 years in men) than those who had never drank or smoked. Those who had never smoked but drank or who had never drank but smoked were each an average of 5.2 years younger at cancer diagnosis than those who neither smoked nor drank. Individuals who stopped drinking one year or more prior to the study and had never smoked developed cancer an average of 2.1 years earlier than those who had never drank or smoked. The effect of smoking appeared to be particularly large for women; women who smoke but never drank developed cancer 6.3 years younger than those who never drank or smoked, compared with 3.7 years in men. In additional, current alcohol and tobacco consumption was associated with an increased likelihood of distal colorectal cancer, although women in all categories were less likely to have distal cancer than men.
These findings suggest that individuals who smoke and drink should undergo screening for colorectal cancer beginning at a younger age, the authors write. In addition, women who do not smoke or drink may be more prone to proximal cancers and might therefore want to consider undergoing colonoscopy instead of flexible sigmoidoscopy. "In the future, we envision the development of risk scores with exogenous (e.g., alcohol and tobacco use, age, body mass index, diet and calcium consumption) and hereditary factors to tailor an individual's colorectal cancer screening program," they conclude.
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