Celiac disease is an autoimmune condition where ingesting gluten, a protein found in wheat, barley, and rye, triggers an immune response. This reaction damages the small intestine’s lining, impairing nutrient absorption. Because the condition requires a specific genetic makeup, it is highly hereditary and often runs in families. The presence of a family member with Celiac disease is a significant risk factor.
The Specific Risk Percentages for Relatives
The risk of developing Celiac disease is elevated for first-degree relatives, such as an affected parent, child, or sibling. While the disorder affects approximately 1 in 100 people in the general population, the chance for a first-degree relative is much higher, generally cited as 1 in 10 (a 5% to 15% likelihood). Recent research suggests that for children with an affected first-degree relative, the risk might increase with age, potentially reaching up to 17.5% by age ten. The risk level decreases for second-degree relatives, such as aunts, uncles, or grandparents, but remains higher than for the general population.
The Role of Specific Genes in Transmission
Celiac disease susceptibility is linked to two specific human leukocyte antigen (HLA) genes: HLA-DQ2 and HLA-DQ8. These genes code for proteins on immune cells that present foreign substances to the immune system. In genetically predisposed individuals, the receptors produced by these genes bind to gluten protein fragments, initiating the autoimmune process. Nearly all people with Celiac disease (over 95%) carry one or both of these genetic markers. However, 30% to 40% of the general population carries HLA-DQ2 or HLA-DQ8 without developing the condition, demonstrating that these genes are necessary but not sufficient to cause the disease.
Why Genetic Risk Does Not Guarantee Disease
The low rate of actual disease despite the high prevalence of risk genes indicates that Celiac disease is a multifactorial disorder. Only 3% to 5% of individuals who carry the HLA-DQ2 or HLA-DQ8 genes ultimately develop the condition. The onset of Celiac disease requires both genetic predisposition and the occurrence of one or more environmental factors that act as triggers.
One major area of investigation involves infections, as certain viral or intestinal infections may temporarily disrupt the immune system or alter gut health. Changes in the gut microbiome, such as reduced microbial diversity, have also been associated with an increased susceptibility to the disease. The timing and amount of gluten consumption, especially in early childhood, are also considered potential variables that influence the disease’s activation.
Other factors that can precede the onset of symptoms include periods of physical or emotional stress, major surgery, or significant hormonal changes like pregnancy. These events may cause a shift in the body’s internal environment, leading the immune system to react to gluten in a destructive manner. Understanding these potential triggers is important for those with genetic susceptibility.
Recommended Screening and Monitoring for At-Risk Individuals
Given the elevated risk, medical professionals recommend proactive screening for asymptomatic first-degree relatives. Initial screening typically involves a blood test for specific antibodies, primarily tissue transglutaminase IgA (tTG-IgA) and total IgA. For accurate results, the person undergoing antibody testing must be regularly consuming a gluten-containing diet.
Genetic screening, or HLA typing, checks for the presence of the HLA-DQ2 and HLA-DQ8 genes. A negative genetic test effectively rules out the possibility of ever developing Celiac disease. If the genetic test is positive but antibody tests are negative, at-risk individuals should undergo repeat antibody screening every three to five years.