The prevalence of celiac disease among family members of celiac disease patients.

Introduction: Celiac disease (CD) is more common in certain risk groups. Family members of known celiac patients represent the most important group. Serological screening enables us to detect patients before they develop serious complications. HLA typing has also proven to be a valuable diagnostic tool, especially in excluding the disease.

Methods: To assess the prevalence of CD among family members, we screened 106 first-degree relatives (73 parents, 33 siblings; mean age 27.9 years) of 45 celiac patients in NE Slovenia. We analysed antigliadin (AGA) and antiendomysium (EMA) antibodies. Levels of IgG and IgAAGA were determined using the ELISA method, and EMA using indirect immunofluorescence. Serologically positive patients were recalled for intestinal biopsy and were HLA typed. Intestinal biopsy was performed by peroral aspiration capsule or during upper GI endoscopy. Biopsy specimens were examined histologically.

Results: Six family members (5.67%) were both AGA IgG and EMA positive, and one (0.94%) was only EMA positive. All were either HLA DQ2 or DQ8 positive. Nine family members (8.49%) were only AGA IgG positive, two of them lacked the HLA DQ susceptibility alleles. Intestinal biopsy was performed in six family members, and the diagnosis of CD confirmed in five. All were both AGA IgG and EMA positive. They were either symptom-free or had only mild gastrointestinal symptoms, and carried the known HLA DQ risk alleles. The minimum prevalence of CD among family members in NE Slovenia can therefore be estimated at 4.72%.

Discussion: The prevalence of CD among first-degree relatives is much higher than the prevalence of the disease in the general population. Most of these patients have an atypical form of the disease and would therefore be overlooked without an active search. Serological testing is recommended for all first-degree relatives of CD patients; they should also undergo HLA typing to detect those whose HLA phenotype is consistent with CD. This approach can also help in excluding individuals who do not need further diagnostic procedures for CD.