HLA-DQ2/DQ8 genotyping is appropriate only in cases of uncertain diagnosis and in subjects with increased risk, like family members of celiac patients (to exclude from subsequent repeated controls the subjects who are negative) and patients with a disease implying an increased risk of celiac disease (such as diabetes mellitus type 1, selective IgA deficiency, autoimmune thyroiditis, hepatitis autoimmune, Down syndrome, Turner syndrome, Williams syndrome). The test has a limited diagnostic value, because the at risk HLA alleles are also frequent in the healthy population and they are not themselves sufficient to determine the disease, which appears only after exposure to environmental triggers and in the presence of other genetic factors. The analysis of HLA susceptibility genes has mainly a negative predictive value, as the absence of the alleles at risk makes very unlikely the development of the disease. The purpose of the test is to evaluate whether to continue the follow-up in selected cases.