Table 3. Groups at increased risk of developing celiac disease^*1.

Group/disease	Frequency of celiac disease
Children, siblings, parents of celiac patients	Sisters and daughters: 12 to 15%Brothers and sons: 6 to 7% Parents: 3 to 4%
Diabetes mellitus type 1	5 to 9%, of whom 1/3 on diagnosis
Trisomy 21	5 to 6 %
Ullrich–Turner syndrome	6 to 9%
Selective IgA deficiency*2	2 to 8%
Autoimmune thyroiditis	3 to 7%
Autoimmune hepatitis	12 to 13%
IgA nephropathy	3 to 5%

^*1Children and adolescents in these at-risk groups should undergo serum testing for celiac disease even if asymptomatic (2, 3). Whether adults in at-risk groups should be tested is still under discussion. The limited evidence on diet in terms of mortality and morbidity should be borne in mind when deciding this. *2For IgA deficiency, an IgG-based test (tTG, EmA, or DGP) is indicated