ERAP1 rs30187 single nucleotide polymorphism does not confer disease susceptibility in North Indian children with enthesitis-related arthritis

Predictors of long-term functional outcomes of juvenile idiopathic arthritis-enthesitis-related arthritis: a single centre experience

OBJECTIVES

Long-term functional outcomes in enthesitis-related arthritis (ERA) is limited from developing countries. We assessed the clinical and genetic factors that predicted the long-term functional outcome in ERA.

METHODS

Patients with ERA having ≥5 years of disease and >16 years of age were included in this cross-sectional study. Data on clinical features within 6 months of disease onset was collected from hospital records. Bath indices, HAQ Disability Index (HAQ-DI) and World Health Organization's Quality of Life (WHO-QOL) were assessed at last visit. Poor functional outcome (PFO) was defined as BASFI > 1.5 or HAQ-DI > 1. Persistent disease activity (PDA) was defined as BASDAI ≥ 4. Endoplasmic reticulum aminopeptidase 1 (ERAP1) and IL-23 receptor single nucleotide polymorphism genotyping was performed with the TaqMan method and HLA-B27 by PCR.

RESULTS

One hundred and eighty-one patients [170 male, median (interquartile range) age of disease onset 12.5 (10-15) years, disease duration 7 (5-11) years] were recruited. There was a delay in diagnosis of 3 (1-5) years. The median Ankylosing Spondylitis Disease Activity Score (ASDAS)-ESR, BASDAI, HAQ-DI and BASFI at inclusion were 2.6 (1.8-3.6), 2.6 (1-5.2), 0.5 (0-0.5) and 1.6 (0.3-3.2), respectively. BASFI and HAQ-DI correlated with ASDAS-ESR, ASDAS-CRP and WHO-QOL-BREF. Those with PFO (n = 98) had a longer delay in diagnosis (4 vs 2 years, P < 0.001), lower prevalence of arthritis at onset [odds ratio (OR) = 0.3; 95% CI: 0.1, 0.8], higher prevalence of ERAP1 (rs27044) allele C (OR = 7.2; 95% CI: 1.5, 33.7) and higher disease activity currently. Delay in diagnosis (OR = 1.2; 95% CI: 1.08, 1.4) was the sole predictor of PFO in multivariate analysis. One-third of patients had PDA. Tarsitis at disease onset was the sole predictor of PDA (OR = 2.3; 95% CI: 1.009, 5.4).

CONCLUSIONS

PFO was seen in one-half of JIA-ERA in the long-term and was associated with active disease with delay in diagnosis as its sole predictor.

Influence of ERAP1 and ERAP2 gene polymorphisms on disease susceptibility in different populations

The endoplasmic reticulum aminopeptidases (ERAPs), ERAP1 and ERAP2, makes a role in shaping the HLA class I peptidome by trimming peptides to the optimal size in MHC-class I-mediated antigen presentation and educating the immune system to differentiate between self-derived and foreign antigens. Association studies have shown that genetic variations in ERAP1 and ERAP2 genes increase susceptibility to autoimmune diseases, infectious diseases, and cancers. Both ERAP1 and ERAP2 genes exhibit diverse polymorphisms in different populations, which may influence their susceptibly to the aforementioned diseases. In this article, we review the distribution of ERAP1 and ERAP2 gene polymorphisms in various populations; discuss the risk or protective influence of these gene polymorphisms in autoimmune diseases, infectious diseases, and cancers; and highlight how ERAP genetic variations can influence disease associations.