We have described suggestive linkage between microsatellite markers within the cytogenetic region 18q21-23 and SLE, a region where linkage with other autoimmune diseases has also been detected. The Bcl-2 gene located within this region, is a candidate gene because of its role in apoptosis, a physiological mechanism that could be deregulated in autoimmune disease. Furthermore, several studies have found abnormalities of Bcl-2 expression in SLE patients. We therefore sought to determine if the Bcl-2 gene is involved in SLE by studying members of a large cohort of Mexican SLE patients (n = 378) and 112 Swedish simplex families. Using a microsatellite marker and two single nucleotide polymorphisms located within the gene, we were unable to detect association between Bcl-2 and SLE in either population. We also tested whether combinations of alleles of the Bcl-2 and IL-10.G microsatellites would increase the risk for SLE. Our results do not support such hypothesis. Our findings suggest that linkage between SLE and the 18q21-23 region is due to a gene other than Bcl-2.
The association of antibodies to cardiolipin, beta 2-glycoprotein I, prothrombin, and oxidized low-density lipoprotein with thrombosis in 292 patients with familial and sporadic systemic lupus erythematosus.
To determine the prevalence of antibodies to phospholipid-binding plasma proteins (aPL) and to oxidized low-density lipoprotein (OX-LDL), and to study the association of these antibodies with thrombosis and coronary heart disease (CHD) in patients with systemic lupus erythematosus (SLE).
Clinical data and sera from 89 Finnish patients with familial and 203 with sporadic SLE were available for the study. Enzyme-linked immunosorbent assays (ELISA) were used for antibody determination.
The occurrence of thrombosis in our SLE patients was 13.7% (40/292) and of clinically diagnosed CHD was 1.4% (4/292). All antibody assays, except IgM-aCL, were significantly associated with thrombosis. IgG-aCL alone or in combination with anti beta 2-GPI or with anti OX-LDL were reasonably sensitive (38%, 48%, and 58%, respectively) and specific (87%, 80% and 72%, respectively) for a history of thrombosis. A high risk of arterial thrombosis (TIA or stroke) was associated with positivity of IgG-aCL, anti beta 2-GPI, and anti-prothrombin. Venous thrombosis was significantly associated with all other assays except IgM-aCL and anti-prothrombin. No test correlated with CHD, but the number of affected patients was small. There were three multiplex SLE families with two patients having a history of thrombosis: no consistent pattern of aPL or anti OX-LDL was found in these patients.
IgG-aCL alone or in combination with anti beta 2-GPI or anti OX-LDL are sensitive and specific tests for detecting SLE patients at increased risk of thrombosis. The aetiopathogenesis of thrombosis in familial SLE appears to be multifactorial.
C1q deficiency is a rare condition associated with a systemic lupus erythematosus (SLE)-like syndrome and recurrent infections. Here we present the molecular basis behind C1q deficiency in three sisters of Inuit origin. Initial examination for complement deficiency showed no function of the classical complement activation pathway in the patients; the lectin and alternative pathways were intact. No C1q or low molecular weight C1q was detected in sera and no anti-C1q autoantibodies were found. Sequencing of the C1q genes revealed a novel missense mutation (Gly-Arg) in codon 217 of the B chain. All sisters were homozygous for the mutation: both parents were heterozygous. None of 100 healthy controls carried the mutation. Our findings define a third class of molecular mechanisms behind C1q deficiency, where missense mutations cause a lack of detectable C1q-antigen in serum.
Systemic Lupus Erythematosus (SLE) is a systemic autoimmune disease in which the type I interferon pathway has a crucial role. We have previously shown that three genes in this pathway, IRF5, TYK2 and STAT4, are strongly associated with risk for SLE. Here, we investigated 78 genes involved in the type I interferon pathway to identify additional SLE susceptibility loci. First, we genotyped 896 single-nucleotide polymorphisms in these 78 genes and 14 other candidate genes in 482 Swedish SLE patients and 536 controls. Genes with P
HLA-DRB1, -DRB3, -DQA1 and -DQB1 alleles were determined by DNA typing in 51 Scandinavian patients with systemic lupus erythematosus (SLE) and 129 controls. DRB1*03,DRB3*0101,DQA1*0501,DQB1*0201 were significantly increased in the patient group, with relative risks (RR) of 2.80, 3.07, 3.55 and 2.12, respectively. These alleles are in strong linkage disequilibrium, and their possible relative contributions in predisposition to SLE are difficult to distinguish. The strongest association was found for DQA1*0501, which is in linkage disequilibrium with DRB1*03 as well as DRB1*11,12 (DR5). An increased frequency of DRB1*11,12 was observed (RR = 1.89, ns). No association with DRB1*15,16 (DR2) was found. The patients had a higher frequency of HLA class II homozygosity than the controls (RR = 5.05, p = 0.0005). When compared to the low-risk group (nonDRB1*03 class II heterozygotes), the cases homozygous for DRB1*03,DQA1*0501,DQB1*0201, known to be in linkage disequilibrium with the complement allele C4A*Q0, had the highest relative risk of developing SLE (RR = 16.39, p = 0.0002). However non[DRB1*03,DQA1*0501,DQB1*0201] class II homozygotes had a higher relative risk (RR = 4.68, p = 0.0147) than DRB1*03,DQA1*0501,DQB1*0201 heterozygotes, known to carry the C4A*Q0 allele (RR = 2.72, p = 0.0088). This may suggest that HLA class II molecules are directly involved in susceptibility to SLE.
In order to find potential correlations between HLA class II alleles and anti-SS-A, -SS-B, -Sm and anti-snRNP responses among Norwegian patients with systemic lupus erythematosus (SLE), HLA-DRB1, -DRB3*0101, -DQA1 and -DQB1 alleles were determined by DNA typing 50 patients and 108 controls. HLA distributions were analysed in the following autoantibody subgroups: anti-SS-A with -SS-B, anti-SS-A without -SS-B, anti-snRNP without -Sm, anti-SS-A without -snRNP and anti-snRNP without -SS-A. The autoantibodies were detected by EIA (enzyme immunuassay). Patients with anti-SS-A and -SS-B had significantly increased frequencies of DRB1*03, DRB3*0101, DQA1*0501, DQB1*0201 (in linkage disequilibrium) versus controls and versus patients without anti-SS-A and -SS-B. No differences in HLA distribution were found when the group with anti-SS-A alone was compared to the group with anti-SS-A and concomitant -SS-B. Comparing the groups with and without anti-SS-A and -SS-B, the highest RR were found for the alleles DRB1*03, DRB3*0101, DQB1*0501, DQB1*0201 (in linkage disequilibrium) with RR: 16.8, 5.0, 19.6, 10.3, respectively, P
The restriction enzymes MspI and BglII identify two different two-allele restriction fragment length polymorphisms (RFLP) in the human IL-6 genes of healthy Danes. Co-dominant segregation was demonstrated for both marker-systems and the test for Hardy-Weinberg equilibrium showed no significant deviation from expectations. There is a strong correlation between the two marker systems. The two IL-6 RFLP's were studied in Danish patients with rheumatoid arthritis, pauciarticular juvenile rheumatoid arthritis, and systemic lupus erythematosus. The frequencies of the MspI and BglII marker phenotypes did not differ between healthy controls and the three disease groups. No extra or missing DNA fragments were observed in the disease groups when compared with controls.
Ncf1 polymorphisms leading to low production of reactive oxygen species (ROS) are strongly associated with autoimmune diseases in animal models. The human NCF1 gene is very complex with both functional and non-functional gene copies and genotyping requires assays specific for functional NCF1 genes. We aimed at investigating association and function of the missense single nucleotide polymorphism (SNP), rs201802880 (here denoted NCF1-339) in NCF1 with systemic lupus erythematosus (SLE).
We genotyped the NCF1-339 SNP in 973 Swedish patients with SLE and 1301 controls, using nested PCR and pyrosequencing. ROS production and gene expression of type 1 interferon-regulated genes were measured in isolated cells from subjects with different NCF1-339 genotypes.
We found an increased frequency of the NCF1-339 T allele in patients with SLE, 11% compared with 4% in controls, OR 3.0, 95%?CI 2.4 to 3.9, p=7.0×10(-20). The NCF1-339 T allele reduced extracellular ROS production in neutrophils (p=0.004) and led to an increase expression of type 1 interferon-regulated genes. In addition, the NCF1-339 T allele was associated with a younger age at diagnosis of SLE; mean age 30.3 compared with 35.9, p=2.0×1(-6).
These results clearly demonstrate that a genetically controlled reduced production of ROS increases the risk of developing SLE and confirm the hypothesis that ROS regulate chronic autoimmune inflammatory diseases.