Rheumatoid arthritis in Poland and Lithuania: different clinical course and HLA associations despite similar genetic background

Application of plantography examination to the assessment of foot deformity in patients with rheumatoid arthritis

INTRODUCTION

Rheumatoid arthritis (RA) is a chronic, inflammatory and multiple-system disorder of connective tissue. It frequently affects joints and periarticular structures of feet that constitute a significant supporting element underlying normal gait and motion of the body centre of gravity. The aim of the study was to evaluate foot deformities on the basis of plantography examination in RA patients according to the severity of the disease.

MATERIAL AND METHODS

The study was performed on 54 RA patients. The control group consisted of 34 volunteers free of any disorders. Plantography examination was carried out by means of a CQ ST2K podoscope. The following parameters were applied to the assessment of the disturbances of foot statics: hallux valgus angle (α), Sztriter-Godunow index (KY), Wejsflog's index (Wwp) and Clarke's angle (CL).

RESULTS

Markedly higher values of the α angle were noted in RA patients, reflecting the presence of hallux valgus. Moreover, values of the α angle were higher in patients in the third stage of radiological changes than those in the second one. On the other hand, values of Clarke's angle for the right foot were significantly higher in men in the second and third stage of RA compared to the control group. The most common deformities in RA patients include HV and transverse flat foot, more explicit in women in the third stage of RA.

CONCLUSIONS

Plantography examination has been shown to constitute a useful diagnostic tool for assessment and monitoring of foot deformities in RA patients.

Association of HLA-DRB1 amino acid residues with giant cell arteritis: genetic association study, meta-analysis and geo-epidemiological investigation

INTRODUCTION

Giant cell arteritis (GCA) is an autoimmune disease commonest in Northern Europe and Scandinavia. Previous studies report various associations with HLA-DRB1*04 and HLA-DRB1*01; HLA-DRB1 alleles show a gradient in population prevalence within Europe. Our aims were (1) to determine which amino acid residues within HLA-DRB1 best explained HLA-DRB1 allele susceptibility and protective effects in GCA, seen in UK data combined in meta-analysis with previously published data, and (2) to determine whether the incidence of GCA in different countries is associated with the population prevalence of the HLA-DRB1 alleles that we identified in our meta-analysis.

METHODS

GCA patients from the UK GCA Consortium were genotyped by using single-strand oligonucleotide polymerization, allele-specific polymerase chain reaction, and direct sequencing. Meta-analysis was used to compare and combine our results with published data, and public databases were used to identify amino acid residues that may explain observed susceptibility/protective effects. Finally, we determined the relationship of HLA-DRB1*04 population carrier frequency and latitude to GCA incidence reported in different countries.

RESULTS

In our UK data (225 cases and 1378 controls), HLA-DRB1*04 carriage was associated with GCA susceptibility (odds ratio (OR) = 2.69, P = 1.5×10(-11)), but HLA-DRB1*01 was protective (adjusted OR = 0.55, P = 0.0046). In meta-analysis combined with 14 published studies (an additional 691 cases and 4038 controls), protective effects were seen from HLA-DR2, which comprises HLA-DRB1*15 and HLA-DRB1*16 (OR = 0.65, P = 8.2×10(-6)) and possibly from HLA-DRB1*01 (OR = 0.73, P = 0.037). GCA incidence (n = 17 countries) was associated with population HLA-DRB1*04 allele frequency (P = 0.008; adjusted R(2) = 0.51 on univariable analysis, adjusted R(2) = 0.62 after also including latitude); latitude also made an independent contribution.

CONCLUSIONS

We confirm that HLA-DRB1*04 is a GCA susceptibility allele. The susceptibility data are best explained by amino acid risk residues V, H, and H at positions 11, 13, and 33, contrary to previous suggestions of amino acids in the second hypervariable region. Worldwide, GCA incidence was independently associated both with population frequency of HLA-DRB1*04 and with latitude itself. We conclude that variation in population HLA-DRB1*04 frequency may partly explain variations in GCA incidence and that HLA-DRB1*04 may warrant investigation as a potential prognostic or predictive biomarker.