Allelic and haplotypic HLA analysis in patients with psoriatic arthritis: Low frequency of common alleles.

INTRODUCTION

Psoriatic arthritis is a complex disease, and human leukocyte antigens (HLA) are key to its development. Latin America and, specifically, Colombia, has scarce data about patients with psoriatic arthritis.

OBJECTIVE

To describe the genotypic, allelic and haplotypic frequency of HLA alleles in psoriatic arthritis and associate them with clinical variables.

MATERIALS AND

METHODS

We conducted a retrospective study involving adult patients with psoriatic arthritis, evaluated according to CASPAR criteria, between 2012 and 2023. We included healthy donors whose HLA-A, B, C, and DR were genotyped by PCR/SSO in a Luminex 100/200 xMAP™ device. We performed an HLA comparative analysis between healthy donors and psoriatic arthritis patients.

RESULTS

We included 401 healthy controls and 37 patients with psoriatic arthritis, in which we identified 46 genotypes, 75 alleles, and 32 haplotypes. The most frequent HLA were HLA-A*24 (37.1%), HLA-B*35 (20.8%), HLA-C*3 and HLA-C*7 (19.9% each), and HLADR* 4 (30%). Compared to healthy donors, the patient’s genotypic frequency was lower for HLA-A*02, HLA-A*11, HLA-B*35, HLA-DR*01, HLA-DR*07, HLA-DR*13, and HLA-DR*15 (p < 0.05), which means that even though HLA-B*35 was frequent in psoriatic arthritis, it's frequency was lower when compared to that of healthy controls. The frequency of HLA-A*24 and HLA-B*44 was different in cutaneous involvement (p < 0.05), HLA-B*40 and HLA-B*35 in joint involvement (p < 0.05), and HLA-A*26 and HLA-C*16 in extra-articular manifestations (p < 0.05). The allelic frequency of HLA-A*26:01 and HLA-C*16:01 in extra-articular manifestations was also significant. The frequency of HLA-Cw*6 was 6.7% and the allele HLA-B*27 was absent.

CONCLUSIONS

The HLA analysis in psoriatic arthritis showed a low frequency of HLA-C*06 and absence of HLA-B*27, different from the information reported for Caucasian population. These results also revealed other alleles of interest. Found differences could be related to the important racial mixing of our population.