HLA-B and HLA-C Alleles in Patients with Psoriasis, Psoriatic Arthritis and Undifferentiated Spondyloarthritis in a Tertiary Care Hospital of Bangladesh

Background: The frequency of HLA-B and HLA-C alleles differs among psoriasis, psoriatic arthritis, and undifferentiated spondyloarthritis, showing unique genetic risks. These genetic links demonstrate how MHC class I alleles affect immune issues, influencing clinical classification andresearch for specific treatments.

Objective: To determine the frequency of HLA-B and HLA-C alleles in patients with psoriasis, psoriatic arthritis (PsA), and psoriatic phenotype of undifferentiated spondyloarthritis (uSpA), with clinical features suggestive of psoriatic arthritis but do not fulfill the CASPAR criteria.

Methods: The cross-sectional study involved 29 patients with PsA, 23 with uSpA, 33 with psoriasis, and 30 healthy controls. Symptoms in uSpA patients suggest PsA, including dactylitis, enthesitis, back pain, DIP involvement, and FADES-like skin changes. HLA-B and HLA-C alleles were detected.

Results: In PsA patients HLA-B*27 allele was detected in 9 (31.03%, p=0.67); HLA-B*15 in 9 (31.03%, p=0.49), HLA-B*38 in 2 (4.5%, p=0.20) and HLA-C*8 in 10 (34.5%, p=0.02). In uSpAfrequency of HLA-B*38 (N=15, 65.21%, p=0.07) and HLA-C*4 alleles (N=8, 34.8%, p=0.20) were more frequent than the healthy controls. Among uSpA patients with DIP involvement, the frequency of HLA-B*38 (N=7, 43.8%, p=0.01) was increased and those who had FADES like skin lesions, HLA-B*38 (N=5, 45.5%, p=0.999) was also increased. Increased frequency of HLA-B*57 was found in psoriatic patients (N=13, 39.4%, p=0.52).

Conclusion: The prevalence of HLA-B*27 and HLA-C*8 is notably elevated in patients with psoriatic arthritis (PsA), whereas HLA-B*38 is found at a lower frequency. In the case of undifferentiated spondyloarthritis (uSpA), individuals exhibiting distal interphalangeal (DIP) joint involvement and presenting with FADES-like skin lesions may show a higher occurrence of HLA-B*38. This observation implies that some patients currently classified as uSpA according to existing criteria might have psoriatic arthritis.