The HLA-DRB4 gene is present in half of the Spanish HLA-DQ2-negative celiac patients

We studied nine consecutive DQ2-negative celiacs [from a group of 186 consecutive celiac disease (CD) patients] for the presence of the HLA-DSB1, DRB1, and DRBx alleles. HLA-DR53 was present in only 5 out of 9 (55%) of DQ2-negative patients. DRB4 (DR53) positivity -39% of chromosomes among Spanish DQ2-negative CD patients is due to both DR4- and DR7-positive cases. Spanish DQ2-positive patients show a high frequency of DR7/DR11 heterozygous carriers of DRB4 (DR53). One-third of our DQ2-negative celiac patients have DRB1*04 (DR4). Six patients are DR4 negative: at least one of the DQ2 alleles (DQA1*0501/DQB1*02) is present in four cases, but none of the alleles of risk, including DR53, were found in the remainding two cases, both of whom carry DQB1*06 alleles (*0602/3 and 0604). The fact that half of our DQ2-negative patients lack DRB4 (DR53) leads us to believe that this gene is not an essential factor to confer CD susceptibility.