Is there a genetic test for Type 1 Diabetes?

Is there a genetic test for Type 1 Diabetes?
Type 1 Diabetes is a chronic condition that impacts the ability of a person’s pancreas to create sufficient insulin. Without insulin, blood sugar can’t get into the cells and stays in the bloodstream. Whether you have a family member with Type 1 Diabetes or you’re curious about what the latest science has to offer, let’s understand what’s currently possible to detect through genetic testing. 
Written by Christina Ren, Certified Genetic Counselor 
Orchid offers advanced genetic testing for couples who want their child to have the best shot of a healthy life. “Genetics for Humans” is where we unpack how genetics impacts our everyday lives and the latest tools to help you build a healthier family.

What is Type 1 Diabetes and how does it impact individuals?

“Diabetes” is a term thrown around a lot, and what most people are referring to is Type 2 Diabetes, which often develops later in life. Type 1 Diabetes (T1D), however, typically impacts individuals in their early childhood to young adulthood years. It is thought to be an autoimmune disease in which the body attacks its pancreatic cells that produce insulin by mistake. 

There is currently no prevention or cure, and individuals with T1D are dependent on injecting or pumping insulin for life. Managing blood sugar levels is critical since very low or high blood sugar levels can be life-threatening, and health complications can also arise. Managing T1D involves a lifetime of ever-changing challenges as it never just “goes away” — here are a collection of stories from people about their life with T1D. 

How common is Type 1 Diabetes? 

In the United States, about 1.6 million people are living with T1D. Many individuals develop symptoms during childhood or adolescence. 64,000 Americans are newly diagnosed each year. 

Is Type 1 Diabetes genetically inherited? 

Evidence that there is a strong genetic component to T1D comes from studies of identical twins since they share 100% of their DNA. 

Early studies have found that if one twin develops type 1 diabetes, the other twin has about a 1 in 2 chance, or 50%, of developing it, too. This is true even if they were raised separately, meaning they had different environmental exposures, and the only common thread is sharing the same genes.

We also see T1D “clustering” in families — first-degree relatives (children, full siblings) of an individual with T1D have an 8 to 15-fold increased chance of developing T1D compared to the general population. Fathers with T1D also tend to impact their child’s chances of developing diabetes more often than mothers with T1D. 

Is there a single genetic cause for Type 1 Diabetes?

The short answer is no — there isn’t a specific “Type 1 Diabetes Gene” like the Huntington’s disease gene that explains it all. 

In the past, what researchers have found is that there is a cluster of genes that encode for immune response proteins that often don’t work properly in individuals with T1D. Known as the human leukocyte antigen (HLA) complex, these proteins help the immune system properly recognize which are the body’s own cells and what are foreign invaders like viruses and bacteria. If the HLA complex fails to recognize the body’s own cells, stuff like the pancreatic cells that produce insulin being mistakenly destroyed can happen. 

But knowing what variation your HLA genes have is not predictive enough. HLA variations account for 40-50% of genetic risk for Type 1 Diabetes. This means you can have the normal working versions of the HLA genes and still develop T1D. If you were to just do genetic testing looking for these HLA variations, it wouldn’t be a good predictive test to tell you whether you or your future child could develop Type 1 Diabetes. 

So what’s beyond HLA genotyping? It turns out there are even more genes involved. What’s become increasingly apparent for the vast majority of people with Type 1 Diabetes is that there is no single genetic cause. The reality is more complex. To properly measure genetic predisposition to T1D, you have to assess the whole landscape by looking at many genes and genetic markers combined.  

Is there a genetic test for Type 1 Diabetes today?

Yes, there is now a way to measure your genetic predisposition to Type 1 Diabetes with considerably better prediction capabilities than HLA genotyping alone. This is different from a diagnosis; however, environmental risk factors such as early childhood infection exposures can trigger disease development. Genetic screening can tell you if you are more or less likely to develop Type 1 Diabetes than the average person based on your genetic background. 

So, with advanced genetic testing like what we do here at Orchid, you can get a sense of your genetic predisposition to Type 1 Diabetes and remove some of the guesswork on what you can pass on to your future children. 

This is done by comparing the genetic makeup of tens of thousands of individuals diagnosed with Type 1 Diabetes (“cases”) with individuals without T1D (“controls”). This analysis finds many genetic markers that show up more often in people with T1D than the general population. Researchers found that individuals with an elevated genetic risk (over the 90th percentile) represent 77% of T1D cases in the general population. 

What actions can I take based on the information from a genetic test for Type 1 Diabetes?

If your future child has an elevated genetic risk for Type 1 Diabetes, the risk of developing T1D at some point in their life can be up to 10, to even 30, times higher than in the general population. 

The useful thing about your results is that if you identify certain genetic vulnerabilities that can impact your future children, you can potentially do something about it and mitigate these risks. 

Key takeaways 

  • Type 1 Diabetes is an autoimmune condition that involves a lifetime of medical management without any current cure. 
  • Past family studies have shown that genetics plays a big role in the chance of developing Type 1 Diabetes. 
  • Advanced genetic testing can now see if this genetic component to Type 1 Diabetes can be quantified for you and your family. 

Orchid offers advanced genetic testing for couples planning on building their family. We use advanced tools and smart, caring humans to help you give your future children the best shot of a healthy life. Conceive with greater confidence and peace of mind

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