There has been a lot of talk about Direct-To-Consumer (DTC) genetic testing and the caveats that come along with that type of testing, but what does it all really mean? What is the actual difference between a DTC genetic test and a genetic test ordered by a medical professional through a clinical laboratory? There are several things that make these tests different but the biggest difference to be aware of is the thoroughness of the testing. 

Think of your genome as a book about you. Each one of your genes is a chapter in the book. Your DNA sequence is all of the letters that make up the words in each chapter.

Testing from a quality clinical laboratory will read each word in a requested chapter, and it will also make sure that large sections of the chapter are not missing or duplicated by mistake.

Most DTCs do their testing with an assay called a SNP array. This type of testing reads only specific letters in a chapter but not the whole chapter. Not even a whole sentence. In addition, this type of testing does not look for large sections that are missing or duplicated at all.

For example, 23andMe has recently been FDA approved to report on 3 specific alterations in BRCA1 and BRCA2 genes. These two chapters (genes) together contain roughly 16,000 letters.  The 3 alterations being analyzed and reported on involve only 4 out of the roughly 16,000 letters in both chapters. The rest of the letters/words are not read.

While DTC tests are very popular and can be entertaining, it is important for individuals to be aware of what they get with this testing and what they DON’T get – especially when dealing with health related topics that could impact an individual’s medical management.