October 28, 2014 6:22 pm
Updated: November 25, 2014 12:26 pm

What you should know about genetic testing kits

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Watch above: Dr. Samir Gupta talks to Leslie Roberts about genetic testing kits. 

TORONTO –Testing for genes associated with certain diseases can be attractive for would-be parents looking to protect their unborn children but there are some risks associated with the practice.

Namely, eliminating the genes associated with certain diseases might not stop a person from contracting the disease.

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“Most common diseases and traits are actually inherited in a polygenic fashion, which means that many different genes actually play a role in that disease and the interplay between those genes and the environment,” Global News medical contributor Dr. Samir Gupta said.

Gupta explains researchers conduct genome wide association studies to look for gene variants and test whether they are associated with a certain disease. Sometimes, one gene variant may be found in 20 per cent of people with the disease – but not everyone.

“It doesn’t mean that if you have the mutation you’ll get the disease, nor does it mean that if you don’t have the mutation you’re protected from the disease,” Gupta said.

But genetic testing kits aren’t useless: they can provide information to scientists trying to figure out which genes are involved in a disease.

The United States Food and Drug Administration (FDA) recently banned 23andMe, an American genetic testing company, from marketing health-related reports as part of its kits.

The FDA said the company failed to show the tests are safe and effective and could cause customers to seek unnecessary or ineffective care.

Now the company has moved into Canada, offering health and ancestry information based on DNA analysis.  The test gives customers access to 108 health-related reports including information on genetic risk factors.

“The health information available to Canadians focuses on individual genetic markers with well-established associations that have clinical validity and that could be incorporated into the management of an individual’s health,” said 23andMe CEO Anne Wojcicki.

But there are other worries about the tests in Canada: health insurance companies can demand the information. And if you don’t give it up, they can revoke your coverage.

But the tests can test well for monogenic diseases.  Dr. Samir Gupta lists five such diseases:

Cystic Fibrosis

Cystic fibrosis is a rare, destructive lung disease. A person has to receive a faulty gene from each of their parents to have a chance of contracting the disease.

Sickle cell anemia

Sickle cell anemia is a mutation in one of the genes for hemoglobin, which carries oxygen inside red cells. The mutation causes anemia and other complications.

Much like cystic fibrosis, a person needs two copies of the gene for the disease.

Haemophilia

Haemophilia is a genetic mutation which prevents blood from clotting properly and can result in excessive bleeding.  One defective gene is enough to get the disease. The disease also only affects males.

BRCA-1

BRCA-1 is a cancer gene and people would have heard about it because of Angelina Jolie.

The disease is associated with a 60 per cent chance of breast cancer and almost as high a chance of ovarian cancer.

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