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how can genetics help to predict diseases

How Accurate are DNA Tests at Identifying Health Risks?

Because this is such an important topic, I’ll start with the bottom line for those who want a quick answer before they order a DNA health test.

Consumer DNA tests, the kind you order online not the one you get at a hospital, are sometimes accurate at identifying health risks.

But they do not provide a full picture of your health, and sometimes, they can result in a false positive.

A DNA health test is useful if you are worried that there is a hereditary disease such as breast cancer running through your family. But do not act on the results or panic without consulting your doctor or a genetic counselor.

If a DNA health test clears you of a particular disease-causing gene variant, it doesn’t mean that you cannot get that disease.

It may have missed other genetic mutations that might contribute to the disease. Additionally, lifestyle and environmental factors also play a significant role in diseases like cancer.

That’s the short answer. Keep reading for a more detailed explanation of the accuracy of health DNA tests.

How Can Genetics Help to Predict Diseases?

Genetics Help to Predict Diseases

Genetic mutations cause genetic diseases.

A mutation occurs when a gene changes permanently such that it differs from the gene generally found in other people.

Genetic mutations are not always bad. Most are cause no change while some are beneficial.

In some cases, however, a change in the structure of a gene can cause disease. This mutation can also be passed down to your children, increasing the risk of inherited disease.

In decades of DNA research, scientists have identified various genetic mutations that seem to increase the risk of certain diseases.

For instance, mutations in the BRCA1 and BRCA2 genes are strongly associated with breast cancer.

When you provide a DNA sample to 23andMe or whichever other DNA testing service, they look for these known mutations.

Based on the mutations they find the test report can predict, though not always accurately, which diseases you might get.

23andMe currently provides a report on Type 2 diabetes, breast and ovarian cancer, macular degeneration, celiac disease, and several other conditions.

Why The Test May not Always Be Right or Complete

DNA Tests

Health DNA tests are right most of the time. They can accurately find a genetic variant associated with a specific disease.

It doesn’t mean you’ll get the disease, but you are at risk.

However, they also get it wrong many times. Here are a couple of reasons why.

1. They Only Study Part of the Genome

This is the most significant limitation of health DNA tests.

The human DNA has about 20,000 genes.

Out of these, however, only about 2,000 have been studied intensively. 5,400 genes have not been studied at all.

Most of these companies can’t study the entire genome. So they only look for known mutations.

But in the part of the genome that’s left untouched, there could very well be other mutations that increase or decrease the risk of a particular disease.

2. Limited Genetic Research

Most of what 23andMe tells you about your health risks come from external research. But there is no guarantee that the research is accurate.

Some studies identify variants that affect various populations differently.

Some testing companies stretch the truth, taking what a research paper might have cited as probable and interpret it as definite.

Here’s What Experts Recommend

DNA Tests at Identifying Health Risks

As you might expect, experts are hesitant to recommend health DNA tests to people. They are afraid that the information provided is too shallow or even wrong or that people might misinterpret the results.

Their fears are not unfounded.

One analysis of health DNA test reports found that 40% of them were false positives. That is, customers were told they had a particular disease-causing variant when in fact, they did not.

But these tests can also be beneficial as one woman discovered. A 23andMe test resulted in her choosing to get a double mastectomy after she discovered she was at risk of breast cancer.

However, she first got a confirmatory test with a genetic counselor.

That’s the path many experts recommend.

If you do take the test and get a positive result, do not panic, and do not take any action.

Find a genetic counselor and get another in-depth test. Based on the second test, discuss your options with the counselor (if you don’t know any genetic counselor ask your doctor to refer you to a good one).

The same recommendation applies if you upload raw data to third-party services like Prometheus.

Also, keep in mind that a negative test is not a get out of jail free card. You can still get a particular disease, because of mutations that were missed the lifestyle and environmental factors.

About the Author Charles McKnight

I'm just another amateur genealogist investigating my American-Scots-Irish lineage. I built MyFamilyDNATest.com after buying all of the leading DNA tests to discover everything I could about my family history. Hopefully, this site will save you time and demystify the emerging science of DNA-based genealogy, for your family project.

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