Laura Ioana Cherciu, Marius Cherciu, Luis Ovidiu Popa, Mihai Bojinca, Monica Irina Dutescu, Violeta Bojinca, Constantin Bara and Olivia Mihaela Popa

ABSTRACT

Objective. Our aim was to investigate whether two ERAP2 single nucleotide polymorphisms (rs2910686 and rs2248374) influence spondyloarthritis (SpA) susceptibility in Romanians.
Methods. The case control study included 139 controls and 192 SpA patients. The two polymorphisms were genotyped by real time polymerase chain reaction (RT-PCR). The association tests for allele, genotype and haplotype frequencies for each polymorphism were performed with PLINK 1.9.
Results. The genotypes and allele frequencies of the two SNPs in general SpA group vs. controls showed no association except for a possible marginal one for the minor allele A of rs2248374 (p = 0.08). In HLA-B27 negative SpA cohort the minor allele (A) frequency (55.4%) of SNP rs2248374 was significantly higher than the one in HLA-B27 controls (44.5%) (p = 0.012). HLA-B27 negative carriers of minor allele A present a higher risk of developing SpA (p = 0.015). Also for the second ERAP2 gene variant investigated (rs2910686) the minor allele T frequency was significantly higher (46.5%) in HLA-B27 negative SPA patients when compared with HLA-B27 negative controls (36%) (p = 0.02). The haplotype of the minor alleles (AC) is a risk factor for HLA-B27 negative SpA (p = 0.019), while the haplotype of the major alleles (GT) is a protective one against the disease in HLA-B27 negative cohorts (p = 0.009).
Conclusions. Both ERAP2 gene polymorphisms investigated, especially rs2248374, influence SpA susceptibility, but this influence is limited only to the HLA-B27 negative individuals.

Keywords: ERAP2 gene, seronegative spondyloarthropathies (SpA), human leukocyte antigen (HLA)-B27, single nucleotide polymorphisms (SNPs)

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Laura Ioana Cherciu, Marius Cherciu, Luis Ovidiu Popa, Mihai Bojinca, Monica Irina Dutescu, Violeta Bojinca, Constantin Bara and Olivia Mihaela Popa

ABSTRACT

Objective. The aim of this study was to investigate whether two IL1A gene polymorphisms, rs17561 and rs1800587, influence disease susceptibility for seronegative spondyloarthropathies (SpA) in Romanians. Subsequently, we analysed separately ankylosing spondylitis (AS) and psoriatic arthritis (PsA) subgroups in relation with the two IL1A gene variants.

Methods. The study included 240 SpA patients (140 AS and 100 PsA patients) and 160 healthy controls. Real-time polymerase chain reaction (RT-PCR) was used to genotype the two single nucleotide polymorphisms (SNPs). Allele, genotype and haplotype frequencies of each SNP were compared between SpA patients and controls and also between AS and PsA cohorts and controls. The PLINK 1.9 software package was used to assess the potential associations; p values ≤ 0.05 were considered significant.

Results. The minor allele T frequency for rs17561 polymorphism was similar in general SpA cohort (31.4%) compared with controls (32.8%), the statistical analyses confirming the lack of association (p=0.67). Almost identical results were found for rs1800587: minor allele T frequency was 29.1% in SpA patients and 29.7% in controls (p=0.85). The same pattern persisted for the separate analysis of HLA-B27 positive SpA patients or AS and PsA cases against controls.

Conclusions. The IL1A gene polymorphisms (rs17561 and rs1800587) do not influence the disease predisposition for seronegative spondyloarthropathies in general, nor for ankylosing spondylitis and psoriatic arthritis in particular, in Romanians.

Keywords: IL1A gene, seronegative spondyloarthropathies (SpA), ankylosing spondylitis (AS), psoriatic arthritis (PsA), single nucleotide polymorphisms (SNPs)

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