High-resolution HLA analysis of primary and secondary Sjogren's syndrome: a common immunogenetic background in Mexican patients

To compare the distribution of HLA-A, B, DRB1 and DQB1 alleles among Mexican patients with primary Sjogren Syndrome (pSS), secondary SS (sSS), connective tissue disease (CTD) without (w/o) SS and historical ethnically healthy controls. We included 28 pSS, 30 sSS, 96 CTD w/o SS patients and 234 controls. HLA-A, B, DRB1 and DQB1 were amplified and sequenced using the Allele SEQR Sequenced Based Typing Kits and analyzed on the ABI Prism*3130 DNA Analyzer using the Assign software. Gene frequencies were obtained by direct counting. Contingence tables of 2 x 2 were generated and analyzed by the Mantel-Haenzel chi (2) or Fisher's test (EPIINFO program). We reported odds ratios (OR) and corrected p values. SS patients showed increased frequencies of A*68:01 and DRB1*14:06 alleles when compared to CTD w/o SS (OR 4.43, 95 % CI 1.35-14.14, p = 0.007 and OR 14, 95 % CI 1.68-116, p = 0.001, respectively) and a higher prevalence of DRB1*01:01 (OR 5.9, 95 % CI 2.13-16.56, p = 0.003) and HLA-B*35:01 (OR 3.70, 95 % CI 1.92-7.12, p = 0.004) when compared with controls. pSS patients had a higher frequency of DRB1*14:06 allele than sSS (OR 16, 95 % CI 1.59-390, p = 0.001). Anti-Ro/SSA positivity was associated with B*51:01 (OR 10.11, 95 % CI 1.09-245, p = 0.02) and DRB1*03:01 alleles (OR 4.26, 95 % CI 1.01-18.89, p = 0.029), whereas the A*01:01 allele was associated with anti-La/SSB positivity (OR 4.75, 95 % CI 1.32-16.92, p = 0.003). In our population, the DRB1*14:06 allele was associated with primary and secondary SS implying that both varieties bear a similar immunogenetic background.