| 1. |
- Abelson, Anna-Karin, et al.
(författare)
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No evidence of association between genetic variants of the PDCD1 ligands and SLE
- 2007
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Ingår i: Genes and Immunity. - : Springer Science and Business Media LLC. - 1466-4879 .- 1476-5470. ; 8:1, s. 69-74
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Tidskriftsartikel (refereegranskat)abstract
- PDCD1, an immunoreceptor involved in peripheral tolerance has previously been shown to be genetically associated with systemic lupus erythematosus (SLE). PDCD1 has two ligands whose genes are located in close proximity on chromosome 9p24. Our attention was drawn to these ligands after finding suggestive linkage to a marker (gata62f03, Z=2.27) located close to their genes in a genome scan of Icelandic families multiplex for SLE. Here, we analyse Swedish trios (N=149) for 23 single nucleotide polymorphisms (SNPs) within the genes of the PDCD1 ligands. Initially, indication of association to eight SNPs was observed, and these SNPs were therefore also analysed in Mexican trios (N=90), as well as independent sets of patients and controls from Sweden (152 patients, 448 controls) and Argentina (288 patients, 288 controls). We do not find support for genetic association to SLE. This is the first genetic study of SLE and the PDCD1 ligands and the lack of association in several cohorts implies that these genes are not major risk factors for SLE.
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| 2. |
- Johansson, C. M., et al.
(författare)
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Characterization of a susceptibility locus for SLE, SLEB5, on chromosome 4p14-13
- 2006
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Ingår i: Scandinavian Journal of Immunology. - : Wiley. - 0300-9475 .- 1365-3083. ; 64:3, s. 308-313
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Tidskriftsartikel (refereegranskat)abstract
- Systemic lupus erythematosus is a systemic autoimmune disorder of unknown aetiology but is most likely caused by an interaction between several genetic factors and the environment. In a previously published genome scan we presented linkage to a marker on chromosome 4p13 in Icelandic families. Fine mapping of the region has been performed using 10 multicase families from Iceland and the maximum two-point LOD score was given by marker D4S2974 (Z = 3.57, alpha = 1). Multipoint analyses of the markers in the region suggest a putative disease gene to be located between markers D4S405 and D4S2381. The maximum multipoint LOD score (Z = 3.76) was given for marker D4S2974 in combination with the novel repeat GT4C2. A family-specific haplotype was segregating with the disease in each of eight families although a founder haplotype could not be identified. Analysis of recombination events in the patients delimited the susceptibility locus to approximately 3 cM. The susceptibility locus identified probably contains a mutation that has been enriched in the Icelandic population but is less common in other populations. We also show that this region is not identical to a susceptibility locus for SLE located on 4p16 where we detect no linkage.
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| 3. |
- Kristjánsdóttir, Helga, 1966-, et al.
(författare)
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A study of the genetic basis of C4A protein deficiency. Detection of C4A gene deletion by long-range PCR and its associated haplotypes.
- 2004
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Ingår i: Scandinavian Journal of Rheumatology. - : Informa UK Limited. - 0300-9742 .- 1502-7732. ; 33:6, s. 417-22
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Tidskriftsartikel (refereegranskat)abstract
- Objective: Study the frequency of C4A gene deletions as the genetic basis of C4A protein deficiency (C4AQ0) and its associated haplotypes in Icelandic SLE families. Materials and methods: Nine multiplex SLE families were genotyped for C4A gene deletions using LR-PCR and MHC haplotypes were defined. Results: Of SLE patients, first- and second-degree relatives, 53,8%, 47,9% and 28,6% had C4AQ0, respectively. A C4A gene deletion is the genetic basis for C4AQ0 in 64,3% of SLE patients, 60,0% of first-degree and 50,0% of second-degree relatives. All individuals carrying haplotype B8-C4AQ0-C4B1-DR3 had a deletion and the deletion was also found on haplotypes B8-C4AQ0-C4B1-DR7 and B7-C4AQ0-C4B1-DR3. Conclusion: The study shows that a C4A gene deletion is the most common genetic basis for C4AQ0. It accounts for 2/3 of C4AQ0 and is found on different MHC haplotypes. 1/3 of C4AQ0 is due to other yet undefined genetic changes. The results thus demonstrate a heterogeneous genetic background for C4AQ0, giving further support for the hypothesis that C4AQ0 may be an independent risk factor for SLE.
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| 4. |
- Kristjánsdóttir, Helga, 1966-, et al.
(författare)
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Association of three systemic lupus erythematosus susceptibility factors, PD-1.3A, C4AQ0, and low levels of mannan-binding lectin, with autoimmune manifestations in Icelandic multicase systemic lupus erythematosus families
- 2008
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Ingår i: Arthritis and Rheumatism. - : Wiley. - 0004-3591 .- 1529-0131. ; 58:12, s. 3865-3872
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Tidskriftsartikel (refereegranskat)abstract
- Objective: To study autoimmune diseases and autoantibodies in Icelandic multicase systemic lupus erythematosus (SLE) families and to determine the association of 3 SLE susceptibility factors, PD-1.3A, C4AQ0, and low levels of mannan-binding lectin (MBL), with autoimmune disease in this population. Methods: Eight SLE multicase families were studied, comprising a total of 124 family members (23 patients with SLE and 101 relatives). The diagnosis of an autoimmune disease was established and autoantibodies were measured in each family. In addition, PD-1.3A alleles were genotyped, and C4AQ0 allotypes were established by electrophoresis and haplotype analysis. Low levels of MBL were determined using enzyme-linked immunosorbent assay and variant-allele genotyping. Results: In the SLE multicase families there was a high frequency of other autoimmune diseases (32.2%) and a high frequency of autoantibodies (53.2%). Of all family members, 59.7% were determined to have SLE, other autoimmune diseases, antinuclear antibodies, and/or other autoantibodies. The families showed genetic heterogeneity for PD-1.3A, C4AQ0, and low MBL levels; the frequency of each factor ranged from 0% to 85%. The frequencies of PD-1.3A and C4AQ0 were significantly increased in patients with SLE, relatives with other autoimmune diseases, and non-autoimmune disease relatives compared with controls. In the 7 families whose members had low levels of MBL, this factor was significantly associated with SLE, but the frequency of low MBL was decreased in relatives with other autoimmune diseases as compared with non-autoimmune disease relatives and controls. There were indications of an additive effect, and 91% of patients with SLE, 78% of relatives with other autoimmune diseases, and 75% of non-autoimmune disease relatives carried at least 1 of the 3 factors. Conclusion: These results demonstrate a high frequency of autoimmune diseases and autoantibodies in SLE multicase families. PD-1.3A and C4AQ0 are part of a predisposing genetic background. Other genetic and/or environmental factors are necessary for disease expression, demonstrated by a high frequency of PD-1.3A and C4AQ0 in non-autoimmune disease relatives. Low MBL levels may be one such contributing factor. The results of this study provide an example of epistatic genetic effects and overlapping genetics in autoimmune diseases.
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| 5. |
- Kristjánsdóttir, Helga, 1966-, et al.
(författare)
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Lower expression levels of the programmed death 1 receptor on CD4+CD25+ T cells and correlation with the PD-1.3A genotype in patients with systemic lupus erythematosus
- 2010
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Ingår i: Arthritis and Rheumatism. - : Wiley. - 0004-3591 .- 1529-0131. ; 62:6, s. 1702-1711
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Tidskriftsartikel (refereegranskat)abstract
- OBJECTIVE.: A genetic polymorphism, PD1.3A, in the PDCD1 gene encoding the co-inhibitory immunoreceptor PD-1, has been associated with SLE. The aim of the study was to assess PD-1 receptor expression in SLE patients, relatives and controls and correlate with PD-1.3A. METHODS.: Icelandic and Swedish SLE patients, relatives and controls were studied. PBMCs were stimulated with alphaCD3/CD28 and PD-1 expression analyzed by flow cytometry. PD-1.3A/G genotyping was performed by PCR-RFLP. RESULTS: I. PD-1 expression on PBMCs was induced after stimulation, by 2.1-fold in SLE patients, 3.1-fold in relatives and 5.1-fold in controls.II. The frequency of PD-1+ cells was significantly lower in SLE patients compared to relatives and controls. PD-1 expression on PD-1+ cells was significantly lower in SLE patients and relatives.III. PD-1 expression on CD4+CD25+ T cells was significantly lower in SLE patients and relatives.IV. PD-1 expression was significantly higher on CD25(high) compared to CD25(intermediate) and (low) cells.V. PD-1 expression on CD25(high) and CD25(intermediate) cells was significantly lower in SLE patients compared to controls.VI. PD-1 was expressed on both FoxP3- and FoxP3+ cells.VII. Lower PD-1 expression was significantly correlated with the PD-1.3A/G genotype. CONCLUSION.: The study demonstrates significantly lower PD-1 receptor expression in SLE patients and relatives and a significant correlation of lower PD-1 expression with the PD-1.3A allele. We conclude that PD-1.3A may be contributory to abnormalities in PD-1 receptor expression on CD4+CD25+ T-cells in SLE, providing support for an important role for the PD-1 pathway in SLE and possibly other autoimmune diseases.
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| 6. |
- Kristjánsdóttir, Helga, 1966-
(författare)
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The PD-1 pathway and the complement system in systemic lupus erythematosus
- 2009
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Autoimmune diseases occur in up to 3-5% of the general population and represent a diverse collection of diseases with regards to clinical manifestations. The unifying factor of autoimmune diseases is tissue and organ damage as a result of an immune response mounted against self-antigens. Systemic lupus erythematosus (SLE) is considered a prototype of human systemic autoimmune diseases. The etiology of SLE is as yet largely unknown, but both epidemiological and genetic data suggest an interplay between numerous and varying genetic and environmental factors. There is compelling evidence for a strong genetic component in SLE. The disease has a high λsibs value and familial clustering is apparent. Multiple susceptibility loci have been identified, some of which are syntenic between humans and mice and some of which overlap with other autoimmune diseases. This thesis is based on analysis of Icelandic multicase SLE families and Swedish SLE patients. Paper I is a study of the association of C4A protein deficiency (C4AQ0) with SLE in the multicase families and shows a significantly increased frequency of C4AQ0 in the families. The genetic basis for C4AQ0 varies and C4AQ0 is found on different MHC haplotypes, pointing to C4AQ0 as an independent risk factor for SLE. Paper II describes the association of low MBL serum levels with SLE in the families and identifies low MBL as risk factor for SLE in families that carry the defect. Low MBL was furthermore found to mediate an additive risk when found in combination with C4AQ0. In paper III cellular expression the PD-1 co-inhibitory receptor on T cells was studied. A polymorphism in the PDCD1 gene, PD-1.3A was previously associated with SLE in the multicase families. The polymorphism is thought to disrupt expression of the gene and may lead to decreased expression of the PD-1 receptor. The study demonstrates lower PD-1 expression in SLE patients and relatives in correlation to the PD-1.3A genotype. Paper IV is a compiled analysis of the SLE families, including PD-1.3A, C4AQ0, low MBL, autoimmune diseases and autoantibody profiles. The study demonstrates clustering of different autoimmune diseases and autoantibodies in families that are heterogenic with regards to the genetic susceptibility factors, PD-1.3A, C4AQ0 and low MBL.
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| 7. |
- Prokunina, Ludmila, et al.
(författare)
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A regulatory polymorphism in PDCD1 is associated with susceptibility to systemic lupus erythematosus in humans
- 2002
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Ingår i: Nature Genetics. - : Springer Science and Business Media LLC. - 1061-4036 .- 1546-1718. ; 32:4, s. 666-669
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Recension (övrigt vetenskapligt/konstnärligt)abstract
- Systemic lupus erythematosus (SLE, OMIM 152700) is a complex autoimmune disease that affects 0.05% of the Western population, predominantly women. A number of susceptibility loci for SLE have been suggested in different populations, but the nature of the susceptibility genes and mutations is yet to be identified. We previously reported a susceptibility locus (SLEB2) for Nordic multi-case families. Within this locus, the programmed cell death 1 gene (PDCD1, also called PD-1) was considered the strongest candidate for association with the disease. Here, we analyzed 2,510 individuals, including members of five independent sets of families as well as unrelated individuals affected with SLE, for single-nucleotide polymorphisms (SNPs) that we identified in PDCD1. We show that one intronic SNP in PDCD1 is associated with development of SLE in Europeans (found in 12% of affected individuals versus 5% of controls; P = 0.00001, r.r. (relative risk) = 2.6) and Mexicans (found in 7% of affected individuals versus 2% of controls; P = 0.0009, r.r. = 3.5). The associated allele of this SNP alters a binding site for the runt-related transcription factor 1 (RUNX1, also called AML1) located in an intronic enhancer, suggesting a mechanism through which it can contribute to the development of SLE in humans.
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| 8. |
- Saevarsdottir, S., et al.
(författare)
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Mannan-binding lectin and complement C4A in Icelandic multicase families with systemic lupus erythematosus
- 2006
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Ingår i: Annals of the Rheumatic Diseases. - : BMJ. - 0003-4967 .- 1468-2060. ; 65:11, s. 1462-7
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Tidskriftsartikel (refereegranskat)abstract
- Objective: To determine whether low mannan-binding lectin (MBL) and C4A null alleles (C4AQ0) are associated with systemic lupus erythematosus (SLE) in multicase families with SLE. Methods: Low MBL level was determined by measuring serum levels and by genotyping for mutant structural (B/C/D, designated as 0) and promoter (LX) alleles (by real-time polymerase chain reaction). C4AQ0 was detected by protein electrophoresis and corroborated with haplotype and genotype analysis. In nine Icelandic families, 24 patients with SLE were compared with 83 first-degree and 23 second-degree relatives without SLE. Twenty four unrelated family members and a population group of 330 Icelanders served as controls. Results: Overall, the frequency of low MBL genotypes (0/0, LX/0 and wild-type/0) tended to be higher in patients with SLE than in their first-degree and second-degree relatives (p = 0.06), but the frequency was similar in the families and in the controls (p = 0.6). The frequency of C4AQ0 was, however, increased in patients and their relatives compared with that in the controls (p = 0.04). The combination of low MBL genotypes and C4AQ0 was found more often in the patients than in their relatives (p = 0.03) and controls (p = 0.02). However, low MBL level was observed only in patients and first-degree relatives in five of the nine multicase families. In these five families, patients with SLE had low MBL genotypes more often (64%) than their first-degree (38%) and second-degree (0%) relatives (p = 0.001), and the patients with SLE also had, accordingly, lower MBL levels than their relatives (p = 0.001). Conclusions: These findings indicate that low MBL levels can predispose people to SLE and highlight the genetic heterogeneity of this disease.
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