How Do We Know the Effects of a Mutation?

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We have more than 22,000 genes. Just over 5,000 of them are disease causing. Our carrier screen looks at around 300 of them. When we look at these genes, we are looking for mutations, or changes, that can lead to disease.

Patients often ask, “How do you know that this mutation causes this effect?” The first step in understanding a mutation’s effect is identifying it via sequencing.

What is gene sequencing?

Gene sequencing is like reading through the DNA code of a particular gene, a set of genes or, in some cases, someone’s full genome. It is one of the most comprehensive ways of doing genetic testing that’s available right now. For couples who want to get as much information as possible, gene sequencing may be the better option for them, as it looks for not only common mutations identified by more basic tests but also rare or novel mutations. Thus, gene sequencing can provide you with the best reduction in residual reproductive risk.

How does gene sequencing work?

Once a patient’s sample arrives at the laboratory, we prepare the DNA for testing and then run it on a sequencer (a very expensive machine), and it gives us a letter code of the patient’s DNA. We then compare that letter code to a reference code, which you can think of as being the code of a “normal” or healthy genome. What we then need to do is find the differences between that patient’s unique code and the reference code. After that comes figuring out what those differences, or variants, mean.

What is variant curation?

Variant curation is essentially the process of figuring out what the variants in someone’s DNA code mean. Not all variants are made equal. Some are ones that will not affect someone’s health in any way, shape, or form. We call these benign. Some variants will cause disease, and those we call pathogenic. For our CarrierMap screen, we only report variants that we strongly believe or know will cause disease. More certainty on your report means less uncertainty and less confusion about what to do with the information.

Who does variant curation?

We have a whole team of variant curators working on your carrier screening results. I am a member of the team and do variant curation two days a week as well as genetic counseling. All of the other members of the team are PhD level individuals with extensive training in human genetics, population genetics, and basic research. We are well-equipped to use the various tools at our disposal to make sure we’re getting you the most

 

Sequencing is like looking at your genes with a fine-toothed comb. It allows us to find mutations we weren’t looking at before. Here, variant curation becomes extremely important. The two together allows us to give you the most up-to-date and accurate information possible about your results.

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About Author

Amber Gamma

Hailing from Canada, Amber works as an Associate Genetic Counselor with CooperGenomics, providing consultations to CooperGenomics' patients and clients. Amber has a strong interest in many areas of genetic counseling, including prenatal counseling, international genetic counseling and LGBTQ issues within the field. Outside of work hours, Amber can be found roaming the streets of New York City with a book and coffee in hand, performing some poetry as part of Stageless Arts' Open Brain events or running around somewhere like the adult child she is.

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