Washington, April 8 (IANS): The US Food and Drug Administration (FDA) has allowed 23andMe, a genetic testing company, to market its "controversial" direct-to-consumer tests for assessing the risk for 10 diseases or conditions, including Alzheimers and Parkinsons disease.

These are the first direct-to-consumer tests authorised by the FDA that provide information on an individual's genetic predisposition to certain medical diseases or conditions, which may help to make decisions about lifestyle choices or to inform discussions with a health care professional.

"Consumers can now have direct access to certain genetic risk information," Jeffrey Shuren, Director of the FDA's Center for Devices and Radiological Health, said in an official statement this week. 

"But it is important that people understand that genetic risk is just one piece of the bigger puzzle, it does not mean they will or won't ultimately develop a disease," Shuren noted.

The FDA approval will likely reignite a long-simmering debate about when and how such tests should be used. Even when there are strong links between certain gene variants and medical conditions, genetic information often remains difficult to interpret, the Scientific American reported on Friday.

The US FDA also cautioned that genetic health risk tests are intended to provide genetic risk information to consumers, but the tests cannot determine a person's overall risk of developing a disease or condition. 

In addition to the presence of certain genetic variants, there are many factors that contribute to the development of a health condition, including environmental and lifestyle factors.

The 23andMe genetic health risk tests work by isolating DNA from a saliva sample, which is then tested for more than 500,000 genetic variants. 

The presence or absence of some of these variants is associated with an increased risk for developing any one of the following 10 diseases or conditions:

Parkinson's disease, a nervous system disorder impacting movement;

Late-onset Alzheimer's disease, a progressive brain disorder that destroys memory and thinking skills;

Celiac disease, a disorder resulting in the inability to digest gluten;

Alpha-1 antitrypsin deficiency, a disorder that raises the risk of lung and liver disease;

Early-onset primary dystonia, a movement disorder involving involuntary muscle contractions and other uncontrolled movements;

Factor XI deficiency, a blood clotting disorder;

Gaucher disease Type-1, an organ and tissue disorder;

Glucose-6-Phosphate Dehydrogenase deficiency, also known as G6PD, a red blood cell condition;

Hereditary hemochromatosis, an iron overload disorder; and

Hereditary thrombophilia, a blood clot disorder.

The US FDA also announced that it plans to offer 23andMe exemptions for similar genetic health risk tests in the future, without requiring them to be submitted for premarket review.