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The Association of HLA and Systemic Sclerosis (SSc) in the Northeastern Thais.

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Mahakkanukrauh A, Suwannaroj S, Romphruk AV, Puapairoj C, Romphruk A, Leelayuwat C, Nanagara R

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Aim: The majority of Thai SSc patients represent a unique ethnic group found in Northeastern Thailand. Genetic susceptibility may be found in the pathogenesis of Thai SSc patients. This study aims to identify HLA genes which correlate with clinical profiles in these SSc patients.

Methods: Peripheral blood samples were taken from 60 SSc patients diagnosed using the ACR classification 1980 criteria. HLA-A, -B, and -C were analyzed using the PCR-amplification refractory mutation system, and the PCR-sequence specific primer was used for the HLA-DR and- DQ analysis. The distribution of the alleles between SSc patients and the control was found to be significant when it was tested with the corrected P value (<0.05).

Results: Of the 60 SSc patients examined; 66.7% displayed symptoms of diffuse cutaneous SSc (dcSSc), and 33.3% showed limited cutaneous SSc (lcSSc). In the Thai SSc group, the prevalence of HLA DRB1*1502 (allele frequency: AF = 32.5%) and DQB1*0501 (AF = 30.8%) which was significantly higher when compared to the control group (AF = 18.5% and 16.3%) with corrected P value (Pc) = 0.0007 and 0.0001, respectively.

Conclusions: The majority of Thai SSc patients that actually displayed dcSSc, had a high prevalence of internal organ involvement.  The results suggest a genetic susceptibility for SSc among the population of Northeastern Thailand, especially for individuals with HLA DRB1*1502.  In the West, there is less HLA DRB1*1502, and this factor could explain why dcSSc is more prevalent among the Thai population.

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systemic sclerosis; scleroderma; HLA; genetic; Thai