It is well known that celiac disease is a genetic disease. The two most common genes associated with celiac disease are human histocompatibility leukocyte antigen (ok, let’s just stick with HLA) DQ2 and DQ8.
Reaching back to my college days I remember loving my genetics course. A very basic review—people inherit one set of genes from each parent. So, for each of our 20,000-25,000 genes we are either heterozygous (different) or homozygous (the same).
For example, we recently found out our daughter is homozygous for the DQ2 gene, meaning she inherited the DQ2 gene from both my husband and me (much to my husband’s surprise!)
The table below shows the opportunity for each of our kids to inherit one of our genes. Mom’s genes down the left hand column, Dad’s genes across the bottom row. So, assuming my husband and I are heterozygous for the DQ2 gene, each of our children would have a 50% (2 out of 4) chance of being heterozygous for the DQ2 gene and 25% each of being homozygous or not carrying the DQ2 gene at all. Clear as mud, right? I’m no genetics instructor! Somehow my college professor made it much more clear and interesting.
|**||heterozygous||**** (unlikely to develop celiac disease)|
The risk categories of developing celiac disease based on your genetic make-up look like this (per Prometheus Therapeutics and Diagnostics):
|Category #||DQ Genotype||Increased Risk||Relative Risk|
|8||DQ2 Homozygous||31X||Extremely High|
|7||DQ2/other high risk gene||16X||Very High|
|2||DQ2/other low risk gene||<1X||Low|
|1||Negative for DQ2 and DQ8||<0.1X||Extremely Low|
Most celiac patients will carry either the DQ2 (95% of celiac disease patients) or the DQ8 (5% of celiac patients). A word of caution, these genetic statistics do not pertain to those with gluten sensitivity.
So, is genetic testing for everyone? Probably not. We had hoped to test the genetics in both our children to compare and better determine the risk of our son, Cohen, developing celiac disease; or (I was hoping) rule out celiac disease. However, due to lab order errors, the genetic portion of the tests were not done on Cohen. In the end it doesn’t really change anything for Emerson-but it certainly is interesting. The fact is, Cohen has a 75% chance of having at least 1 DQ2 gene and will likely mean continued annual antibody screening for him. Hopefully each year the blood draw will get easier and will not include me pulling Emerson from under the chair in the waiting room, needing 3 people to hold Cohen down, and everyone: Emerson, Cohen, me, and grandma (who had graciously agreed to come help me) leaving the clinic in tears.
**The genetic risk category information was taken directly from the Prometheus lab report with my daughter’s results. I am not a genetic counselor and encourage everyone to speak with their physician if they have questions regarding genetic testing.