Different genetic effect of PXK on systemic lupus erythematosus in the Korean population.

PXK was identified as a novel candidate gene for systemic lupus erythematosus (SLE) from genome-wide association studies (GWAS) in Caucasians. But a recent replication study in Hong Kong Chinese reported that PXK was not associated with SLE. The aim of this study was to determine whether PXK is associated with SLE in Koreans. We genotyped single nucleotide polymorphism (SNP) rs6445975 of PXK using the TaqMan assay in 527 Korean patients with SLE and 517 healthy Korean control subjects. Genotypic associations were assessed using multiple logistic regression models. Additional analyses were also performed by subphenotype stratification. No association was detected between PXK rs6445975 and SLE (odds ratio (OR) = 1.06, P = 0.57). PXK rs6445975 showed positive associations with photosensitivity (P = 0.02) and the production of anti-Sm Ab (P = 0.04) among SLE patients. Thus, the association of PXK rs6445975 with SLE that was previously observed in Caucasians was not replicated in Koreans or in Hong Kong Chinese. It is possible that PXK has different genetic contribution on SLE between Caucasians and Asians and that the gene is associated with disease subphenotypes rather than with overall susceptibility.