HLA class I and discoveries of the HLA-K (pseudogene) related to disease severity and progression in patients with spondyloarthritis in Dr. Soetomo General Hospital, a tertiary health care center in Surabaya, Indonesia

Background: Spondyloarthritis (SpA) is a chronic inflammatory disease characterized by enthesitis, sacroiliitis, and axial joint involvement. Although the association of HLA with SpA has been widely reported, there have been no studies of HLA type in the Indonesian population within the last 20 years. This study aims to identify the HLA type in SpA patients at Dr. Soetomo General Hospital, Indonesia. Methods: This study used a cross-sectional analytical design with samples that met the criteria for SpA according to the 2009 ASAS. The clinical scores used in this study were mSASSS, BASFI, ASDAS, and Schober. Genetic identification using PCR was performed followed by sanger sequencing to determine the HLA type in the patient. DNA sequences were aligned with BLAST, and a phylogenetic tree was created using MEGA 11. Descriptive and comparative analyzes were performed using GraphPad Prism 9. Results: This study founded four types of HLA in SpA patients at Dr. Soetomo General Hospital, that is HLA-B with six alleles; -B*2704 (12.86%), -B*2705 (1.43%), -B*2706 (1.43%), -B*1802 (4.28%), -B*57v (1.43%), -B*35 (2.86%), HLA - C (21.43%), and HLA - K (52.83%). Clinical scoring of HLA-C and HLA-K indicated severe and progressive disease activity. The HLA-K had the highest mSASSS (26, 95% CI: 22–28), while HLA-C had the highest BASFI score (60, 95% CI: 55–68), the lowest Schober score (12, 95% CI: 10–14), and the shortest duration of illness (22, 95% CI: 12–36). There is no significant difference in the ASDAS score among types. Conclusions: The most common HLA types found in SpA patients at Dr. Soetomo were HLA-C and HLA-K, with the most progressive disease activity indicated by poor mSASSS, BASFI, ASDAS, and Schober scores with a short duration of illness.