AB0117 HLA B27*SUBTYPES FREQUENCIES IN COLOMBIAN PATIENTS WITH SPONDYLOARTHRITIS AND HEALTHY SUBJECTS TYPED IN HIGH-RESOLUTION TECHNIQUE
Authors: C. Romero-Sánchez, W. Bautista-Molano, Y. M. Chamorro-Melo, A. Beltrán-Ostos, J. De Avila, J. M. Bello-Gualtero, A. Ramos-Casallas, L. Chila, C. F. Pacheco Tena, P. Chalem, C. Florez, V. Parra-Izquierdo, D. Jaimes
Journal: Annals of the Rheumatic Diseases (2020)

Background: HLA-B*27 has been identify as a susceptibility and prognostic factor associated to axial spondyloarthritis. HLA-B*27 allele has been described to be present in about 90% of patients with ankylosing spondylitis, and with a different frequency in patients with other subtypes of SpA. In contrast, this allele has been observed to be present only in 7–8% in general population. A remarkable heterogeneity in HLA-B*27 alleles has been reported. They have been determined at DNA sequence and some subtypes have been associated increasing the risk to develop the disease Objectives: To establish the frequencies of HLA-B27 subtypes in a group of Colombian patients with SpA and healthy population Methods: In total, 61 Blood samples from Colombian mestizo individuals with SpA according to ASAS classification-criteria were evaluated by Sequencing Technology: Illumina Sequencing/PacBio Sequencing with analysis of the second and third exon. Results reported with six digits (including null alleles). In total, 294 results of peripheral blood from healthy individuals without joint symptoms were analyzed. Frequencies were obtained for demographic and genetic variables. Ethic Committee approval code 2018-020/2017-023 Results: The SpA group had a mean age of 45,88 ± 11,67, 62.3% of them were male, 6.6% reported current smoking and 37.7% reported smoking sometime in life. In total, 67.2% had inflammatory back pain, 14.8% had dactylitis, 63.9% enthesitis and 57.4% arthritis. Thirty patients were HLA-B*27 positive with a genotypic frequency of 50.8% and an allelic frequency of 24.6%. In this group of patients, the mean age was 43,5 ± 11,8, 76.6% were male, 86.7% of them were subtype B*27:05:02g and 13.3% presented the B27:02:01g. None of the SpA patients had both B*27 alleles. On the other hand, the healthy individuals were men in 51.0% and the mean age was 37±15.4 years. Ten subjects were positive for the HLA-B*27 allele with a genotypic frequency of 3.4% and an allelic frequency of 1.7%. In this group of individuals 50.0% were male gender with a mean age of 38.4±17.9. No individuals were found to have the two alleles or homozygous for the B*27 allele. In all of them the subtype B*27:05:02g was observed in high-resolution sequencing Conclusion: The SpA group had a mean age of 45,88 ± 11,67, 62.3% of them were male, 6.6% reported current smoking and 37.7% reported smoking sometime in life. In total, 67.2% had inflammatory back pain, 14.8% had dactylitis, 63.9% enthesitis and 57.4% arthritis. Thirty patients were HLA-B*27 positive with a genotypic frequency of 50.8% and an allelic frequency of 24.6%. In this group of patients, the mean age was 43,5 ± 11,8, 76.6% were male, 86.7% of them were subtype B*27:05:02g and 13.3% presented the B27:02:01g. None of the SpA patients had both B*27 alleles. On the other hand, the healthy individuals were men in 51.0% and the mean age was 37±15.4 years. Ten subjects were positive for the HLA-B*27 allele with a genotypic frequency of 3.4% and an allelic frequency of 1.7%. In this group of individuals 50.0% were male gender with a mean age of 38.4±17.9. No individuals were found to have the two alleles or homozygous for the B*27 allele. In all of them the subtype B*27:05:02g was observed in high-resolution sequencing Acknowledgments: Hospital Militar Central (Grant 2017-023/2018-020), the Government Institute of Science, Technology, and Innovation, Francisco Jose de Caldas—COLCIENCIAS (Grant No. 130877757442) and Colombian Rheumatology Association (Grant-Conv-2019) Disclosure of Interests: None declared