Association of PPP2CA polymorphisms with systemic lupus erythematosus susceptibility in multiple ethnic groups.

OBJECTIVE: T cells from patients with systemic lupus erythematosus (SLE) express increased amounts of PP2Ac, which contributes to decreased production of interleukin-2 (IL-2). Because IL-2 is important in the regulation of several aspects of the immune response, it has been proposed that PP2Ac contributes to the expression of SLE. This study was designed to determine whether genetic variants of PPP2AC are linked to the expression of SLE and specific clinical manifestations and account for the increased expression of PP2Ac. METHODS: We conducted a trans-ethnic study of 8,695 SLE cases and 7,308 controls of 4 different ancestries. Eighteen single-nucleotide polymorphisms (SNPs) across PPP2CA were genotyped using an Illumina custom array. PPP2CA expression in SLE and control T cells was analyzed by real-time polymerase chain reaction. RESULTS: A 32-kb haplotype comprising multiple SNPs of PPP2CA showed significant association with SLE in Hispanic Americans, European Americans, and Asians, but not in African Americans. Conditional analyses revealed that SNP rs7704116 in intron 1 showed consistently strong association with SLE across Asian, European American, and Hispanic American populations (odds ratio 1.3 [95% confidence interval 1.14-1.31], meta-analysis P=3.8 710(-7)). In European Americans, the largest ethnic data set studied, the risk A allele of rs7704116 was associated with the presence of renal disease, anti-double-stranded DNA, and anti-RNP antibodies. PPP2CA expression was 3c2-fold higher in SLE patients carrying the rs7704116 AG genotype than those carrying the GG genotype (P=0.007). CONCLUSION: Our data provide the first evidence of an association between PPP2CA polymorphisms and elevated PP2Ac transcript levels in T cells, which implicates a new molecular pathway for SLE susceptibility in European Americans, Hispanic Americans, and Asians

A systemic sclerosis and systemic lupus erythematosus pan-meta-GWAS reveals new shared susceptibility loci.

Systemic sclerosis (SSc) and systemic lupus erythematosus (SLE) are two archetypal systemic autoimmune diseases which have been shown to share multiple genetic susceptibility loci. In order to gain insight into the genetic basis of these diseases, we performed a pan-meta-analysis of two genome-wide association studies (GWASs) together with a replication stage including additional SSc and SLE cohorts. This increased the sample size to a total of 21,109 (6835 cases and 14,274 controls). We selected for replication 19 SNPs from the GWAS data. We were able to validate KIAA0319L (P = 3.31 7 10(-11), OR = 1.49) as novel susceptibility loci for SSc and SLE. Furthermore, we also determined that the previously described SLE susceptibility loci PXK (P = 3.27 7 10(-11), OR = 1.20) and JAZF1 (P = 1.11 7 10(-8), OR = 1.13) are shared with SSc. Supporting these new discoveries, we observed that KIAA0319L was overexpressed in peripheral blood cells of SSc and SLE patients compared with healthy controls. With these, we add three (KIAA0319L, PXK and JAZF1) and one (KIAA0319L) new susceptibility loci for SSc and SLE, respectively, increasing significantly the knowledge of the genetic basis of autoimmunity

Transancestral mapping and genetic load in systemic lupus erythematosus

Systemic lupus erythematosus (SLE) is an autoimmune disease with marked gender and ethnic disparities. We report a large transancestral association study of SLE using Immunochip genotype data from 27,574 individuals of European (EA), African (AA) and Hispanic Amerindian (HA) ancestry. We identify 58 distinct non-HLA regions in EA, 9 in AA and 16 in HA ( 3c50% of these regions have multiple independent associations); these include 24 novel SLE regions (P<5 7 10-8), refined association signals in established regions, extended associations to additional ancestries, and a disentangled complex HLA multigenic effect. The risk allele count (genetic load) exhibits an accelerating pattern of SLE risk, leading us to posit a cumulative hit hypothesis for autoimmune disease. Comparing results across the three ancestries identifies both ancestry-dependent and ancestry-independent contributions to SLE risk. Our results are consistent with the unique and complex histories of the populations sampled, and collectively help clarify the genetic architecture and ethnic disparities in SLE