Celiac.com 01/03/2008 - It’s pretty well documented that HLA-DQ2 and HLA-DQ8 sereotypes are closely associated with celiac disease. Patients who test positive for both sereotypes are at much greater risk for developing celiac disease. Celiac disease is closely associated with the presence of HLA-DQ2 and HLA-DQ8, and has also been tied to variations in the MY09B gene on the 19th chromosome.
Homozygosity is the condition of having two identical genes, of many possible combinations, on a single chromosome site.
HLA-DQ2 homozygosity means that a person has inherited the HLA-DQ2 gene from both parents.
In addition to having a much higher risk of developing celiac disease in general, people with HLA-DQ2 homozygosity have a much higher risk of developing refractory celiac disease type II, and enteropathy-associated T-cell lymphoma. Refractory celiac disease is a rare type of celiac disease in which a gluten-free diet fails to eliminate symptoms and to reverse celiac-associated damage. Eneteropathy-associated T-cell lymphoma is a type of cancer that often develops in people with advanced intestinal damage such as commonly found in celiac patients.
A team of Dutch doctors recently set out to determine if the presence of the MY09B gene carries an elevated risk of refractory celiac disease type II, and enteropathy-associated T-cell lymphoma.
The research team evaluated 62 people who were confirmed to have both refractory celiac disease type II and enteropathy-associated T-cell lymphoma. They also evaluated 421 people with simple celiac disease, along with a control group of 1624 people without celiac disease.
The team conducted genotyping of MY09B along with molecular HLA-DQ2 typing on all of the patients.
The tests showed that one nucleotide variation in MY09B was substantially different in the refractory celiac group than in either the simple celiac or the control group.
The allele in question is known as the rs7259292 T allele, and the results of the tests showed that it occurs far more frequently in patients with refractory celiac and enteropathy-associated T-cell lymphoma than in either the control group or the group with simple celiac disease. In fact, the halpotype that carries the rs7253292 T allele occurs in 11% of the patients with refractory celiac disease type II, and enteropathy-associated T-cell lymphoma compared with just 2% of the control group and 3% or patients with regular celiac disease.
Additionally, the results showed that patients who carry the MY09B rs7259292 allele or who showed HLA-DQ2 homozygosity faced similarly high risk levels for refractory celiac disease type II, and enteropathy-associated T-cell lymphoma compared to patients with simple celiac disease.
The results did not show any connection or interaction between the MY09B rs7259292 allele and HLA-DQ homozygosity.
Clinical Gastroenterology and Hepatology; 2007: 5(12): 1399-1405