Frequency of HLA-DQ, susceptibility genotypes for celiac disease, in Brazilian newborns

Abstract

Background: The frequency of HLA-DQ2 and DQ8 predisposing genotypes for celiac disease (CD) has shown significant variation among different world regions and has not been previously determined among the highly interbred Brazilian population. The aim of this study was to investigate the frequency of these genotypes among Brazilian newborns (NB). Methods: We typed DQA1*05 - DQB1*02 (DQ2.5) and DQA1*03 - DQB1*03:02 (DQ8) alleles in 329 NB using qPCR technique. Subsequently we confirmed our results by PCR-SSP using a reference kit which further identified DQ2.2 (DQA1*02:01 - DQB1*02). Results: Among the 329 NB, using qPCR technique: 5 (1.52%) carried both DQ2.5 and DQ8 variants; 58 (17.63%) carried only DQ2.5 (DQA1*05 and DQB1*02) and 47 (14.29%) carried only the DQ8 (DQA1*03 and DQB1*03:02) variant. The use of the PCR-SSP method yielded further information; among the 329 samples: 34 (10.34%) tested positive for DQ2.2 and among the 47 previously DQ8 positives samples, we found 10 (3.04%) that also tested positives for DQ2.2. Conclusion: 43.7% of the analyzed individual tested positive for at least one of the CD predisposing HLA-DQ genotypes in our group of Brazilian NB. The highest frequency was found for DQ2.5 positive subjects (17.6%) followed by DQ8 (11.3%); DQ2.2 (10.3%); DQ8 and DQ2.2 (3.0%); DQ2.5 and DQ8 (1.5%). We found no positive sample for DQ2.5 associated with DQ2.2.