“Genetic testing has lots of complexities,” says Kotze. “So it’s very important to integrate it with the person’s family history, clinical information and lifestyle. This is what makes our service unique — we look at the full picture, not just the genes. But, whatever genetic test you do, you need to know how you’ll have to change your accordingly lifestyle if you test positive. If you carry familial breast cancer genes, you might need a preventative mastectomy, and if you have the Apo E4 mutation, you’ll need to stop smoking or drinking to reduce the risk of heart disease and Alzheimer’s disease. You have to be prepared for these possibilities before you discover the truth.”
Kotze also told Shape about some of the susceptibility genes that Gene Care tests for and what they say about health…
> LIPID METABOLISM — We test for two forms of the Apo E gene. The Apo E2 mutation is associated with high triglyceride levels, and Apo E4 with elevated cholesterol. If you carry two copies of either gene, your risk is greater than if you carry one, and in the case of the E2 gene, you need a second risk factor (like type-2 diabetes or obesity) to trigger the effect. Thirty to 40% of people carry Apo E4, and if you test positive, smoking or drinking alcohol (even infrequently) leads to a 40% higher risk of heart disease and a two times greater risk of Alzheimer’s. We can also test for the Familial Hypercholesterolemia gene, which increases heart disease risk by 80%.
> FOLATE METABOLISM — The presence of the 677 mutation on the MTHFR gene leads to decreased homocysteine metabolism, particularly if you have low levels of folate and the B vitamins. High homocysteine levels are associated with many conditions (including cancer, osteoporosis, Alzheimer’s and multiple sclerosis) so people with this gene need to consume two times more folate than those without the gene. The 677 mutation also contributes to folate neural tube birth defects in babies. More than 50% of people carry at least one copy of this gene.
> THROMBOTIC RISK FACTORS — The Factor V Leiden gene is present in about 5% of people and increases the risk of venous thrombosis (blood clots) by 50–100% in people with two copies, and 5–10% in people with one. If the prothrombin gene mutation is also present the risk is increased more than 40 times. People with these genes are at risk of traveller’s thrombosis and should take precautions when flying. The thrombosis genes are also implicated in miscarriage and should be considered by reproductive-aged women.
> CANCER Testing can be done for a number of cancer genes, including those for breast (BRCA1 and BRCA2) and inherited colon cancers. If you test positive for a familial breast cancer gene and someone in your family already has the condition, your risk is 80%. But remember that there are many genes involved in this form of cancer, so even if you test negative for these genes, if you have a family history your risk is still two to three times greater than the normal population.
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