8%. The DQ2 positivity of 85% among our first-degree CD relatives is nearly 4.5–8.5 times higher than the general north Indian population, confirming a

strong genetic association in CD. Other studies15–18 have reported 59% to 73% of all first-degree relatives to be positive for HLA DQ2/DQ8. Our figure of 85% is higher than the 73% reported by Rubio-Tapia et al.18 and this may either be due to higher enrollment and HLA DQ2/8 testing in 97% of all existing first-degree relatives in our study in comparison to 60% of all first-degree relatives by Rubio-Tapia et al. or due to genetic variation in different populations. Recognition of an HLA DQ2/DQ8-negative selleck kinase inhibitor first-degree relative, where the index case is HLA DQ2/DQ8-positive, obviates the need for further serological testing. HLA DQ2/DQ8 was negative in 14% of parents and 14.7% of siblings and this would therefore be applicable only to approximately 14.3% of all first-degree relatives in our study. The two studies of HLA DQ2/DQ8 prevalence in CD from North India showed 93% and 97.1% of cases to be HLA DQ2-positive,

respectively, and none to be DQ8-positive.33,34 In our study, 29/30 (96.6%) index cases were HLA DQ2-positive and one (3.4%) was positive only for HLA DQA1*05. In a large European genetic study of CD,35 5.6% (57/1008) of CD cases Y-27632 ic50 had only one of the DQ2 alleles, that is, HLA DQA1*05 or HLA DQB1*02. The authors recommended that clinicians should consider the presence of one half of the DQ2 heterodimer as compatible with the diagnosis of CD and it is very rare for CD to occur without one of these genotypes. In the study by Kaur et al.34 of 35 CD cases, 34 were HLA DQ2-positive and one case (2.8%) was positive only for HLA DQB1*02, which is similar Ponatinib mw to our findings. The absence of DQ8 allele in our CD cases is similar to previous Indian studies33,34 and to

a Spanish study,36 where 92.4% of CD cases were DQ2-positive and none were DQ8-positive. Also, Johnson et al.37 showed that the DQ8 allele was more prevalent in the New York CD cohort as compared to the Parisian CD cohort. We feel that this variance in DQ8 positivity in CD cases may be due to differences in genetics across different populations. In our study, IgA-tTGA-positive relatives were significantly more often symptomatic than the IgA-tTGA-negative subjects. Of the four histologically confirmed new CD cases, three (75%) were symptomatic. This is similar to the 78% (11/14) symptom prevalence in the screen-positive relatives reported by Grover R et al.38 This observation is different from that of the screening studies from the developed world where only 40%–50% of screen-detected cases are symptomatic.