Celiac disease (CD) is frequently associated with an autoimmune disorder (AD). The aim of the study was to establish if an AD is more frequent than expected in relatives of CD patients and, in particular, if it is related to the presence of silent unrecognised CD. We also evaluated the prevalence of ADs in CD patients and compared it with that in a control series. A structured questionnaire was used to evaluate the prevalence of ADs in 125 (51 males and 74 females with a mean age of 8.9 years) children with CD (group A), 125 (67 males and 58 females with a mean age of 8.1 years) matched "healthy" children (group B), all 1352 first- and second-degree relatives of the 125 children with CD (group C), all 1238 first- and second-degree relatives of the control group B of "healthy" children (group D), and all 205 first- and second-degree relatives of 20 children with AD (group E). We also used the antiendomysium antibody assay to screen 354 of the 373 first-degree relatives of group C. An AD was present in 9 of the 125 (7.2\%) children with CD (group A), in 1 of the 125 (0.8\%) healthy children (group B), in 67 of the 1352 (4.9\%) relatives of CD patients (group C), in 14 of the 1238 (1.1\%) relatives of healthy children (group D), and in 7 of the 205 (3.4\%) of relatives of patients with AD (group E). Clinically silent CD was found in 20 of the 354 first-degree relatives of CD patients (5.6\%), and the risk of silent CD was significantly higher, reaching 25\% (4/16) in the subgroup of relatives also affected by another AD. Relatives of CD patients had an increased prevalence of AD compared to control groups, and relatives of CD patients with ADs, have a risk as high as 25\% of being silent celiacs: they should thus be screened for CD.
