Correlation of rheumatology subspecialty choice and identifiable strong motivations, including intellectual interest.

OBJECTIVE: To describe motivations correlating with subspecialty choices, particularly rheumatology. METHODS: A total of 179 respondents answered queries about various aspects affecting specialty and subspecialty choice with ordinal ratings of importance. Likert scale response data were analyzed to determine independent predictors of being a rheumatology fellow. Multivariate logistic regression analyses were used to develop models predicting rheumatology fellowship. Factor analysis methods to condense the individual responses into fewer underlying variables or factors were employed. RESULTS: While every group ranked intellectual interest as more important than all other responses, its score in the rheumatology fellow group was significantly higher than that in the medical student group. A model using 4 composite variables based on prior literature did not fit well. Exploratory factor analysis identified 5 underlying motivations, which were designated as time, money, external constraints, practice content, and academics. All motivations except money were statistically significant, with the rheumatology fellow group attributing greater importance than medical students to time, practice content, and academics, and lesser importance than medical students to external constraints. CONCLUSION: Values and motivations leading toward rheumatology subspecialty choice can be traced to identifiable factors. Intellectual interest appears to be split between 2 distinct significant variables: practice content and academics. Time or controllable lifestyle, external constraints, practice content, and academic issues appear to be important influences on the choice of rheumatology fellowship. Such variables appear to reflect underlying values and motivations.

Interleukin-1 region meta-analysis with osteoarthritis phenotypes.

OBJECTIVE: Several research groups have examined osteoarthritis (OA) association with Interleukin-1 (IL-1) region markers and haplotypes. The results have been suggestive for hand OA, negative for knee OA, and conflicting for hip OA. DESIGN: Our aim was to address conflicts employing meta-analytical methods on data from 1238 European-descent cases with various OA phenotypes and 1269 European-descent controls from four study centers. We imputed some missing genotype data and reconstructed IL-1 region extended haplotypes. A previously reported 7-marker IL1A-IL1B-IL1RN extended risk haplotype was tested for association with each specific index phenotype. RESULTS: For hip OA, data from three centers showed heterogeneity of extended-risk-haplotype effect, two panels showing trend toward risk and another showing protection, with overall odds ratio (OR) 1.24 (95% Confidence interval (CI) 0.45-3.41, P 0.67). The heterogeneity fell partly along control ascertainment lines, chiefly between controls ascertained as spouses of arthroplasty patients and controls identified through population radiographic survey. For knee OA, the results showed no heterogeneity and no significant extended-risk-haplotype effect. For hand OA, the results showed little heterogeneity and a modest trend toward positive association (summary OR 1.34, 95% CI 0.83-2.17 P 0.23). Using a Bayesian partition modeling approach, the 7-marker extended haplotypes showed no significant effect on any OA phenotype examined. A 3-single-nucleotide polymorphism (SNP) IL1B-IL1RN haplotype rs1143627-rs16944-rs419598 showed a trend toward hand OA association (posterior probability of association 0.72) with the most prominent feature being protection from a specific haplotype representing a partial mirror image of the extended risk haplotype (OR estimated at 0.46). CONCLUSIONS: The meta-analysis data do not confirm but only suggest that some hand and hip OA risk could be associated with the IL-1 region, particularly centered in IL1B and possibly also IL1RN.

Potential influence of IL1B haplotype and IL1A-IL1B-IL1RN extended haplotype on hand osteoarthritis risk.

OBJECTIVE: To assess osteoarthritis (OA) association with the human interleukin-1 (IL-1) region. DESIGN: Sixty-four European-descent cases with radiographic hand OA and 48 European-descent controls were genotyped at nine single nucleotide polymorphism (SNP), one variable-number-of-tandem-repeat (VNTR), and one microsatellite marker extending across loci for IL-1alpha (IL1A), IL-1beta (IL1B), and IL-1 receptor antagonist (IL1RN). The genotype data were used to reconstruct individual locus haplotypes, and then locus haplotypes were used as superalleles for extended haplotype reconstruction. RESULTS: Nine different extended IL1A-IL1B-IL1RN haplotypes occurred at a frequency 0.05 or greater in either cases or controls. Only two IL1A-IL1B-IL1RN extended haplotypes were consistent with previously described extended risk haplotypes and totaled n=9 in cases and n=3 in controls [odds ratio (OR) 2.1, Haldane's chi(2) 1.67, one-sided P 0.1]. Our prior report showed hand OA association with homozygous IL1B rs1143633 minor allele genotype. All except one extended risk haplotype copy also had the IL1B rs1143633 minor allele. The rs1143633 genotype association was explained by one common six-SNP IL1B haplotype bearing rs1143633 minor allele and also risk alleles at rs1143634, rs1143627, and rs16944, component markers of the previously described extended risk haplotypes. The IL1B haplotype bearing all three risk alleles was found in 16 haplotype-homozygous hand OA cases and in four haplotype-homozygous controls and conferred OR 3.4 among homozygotes (nominal P value 0.006). CONCLUSION: Our evidence broadly supports the genetic association of OA phenotypes with an IL-1 region extended risk haplotype and specifically IL1B genotype. The extended risk haplotype previously associated with hip OA appears to be less frequent and has weaker genetic effect in hand OA. Hand OA risk is conferred by homozygous state for the IL1B haplotype characteristic of the extended risk haplotype.

Utility of digital photographs of the hand for assessing the presence of hand osteoarthritis.

OBJECTIVES: Nodal osteoarthritis of the hand (hand OA) is a subset of OA with a strong heritable component. Multiple genetic analyses of this condition have been performed and are underway. Highest yield from any genetic study depends upon a clear clinical phenotype for case definition. Radiographs may provide the most detail about the nature of the lesion. Physical examination is an imperfect means of evaluating each patient, particularly when hundreds or thousands of patients are required for study. Our study evaluated the accuracy, relative to a radiograph, of a digital photograph of the hands for the presence of OA in a particular joint, as well as for the diagnosis of nodal hand OA. METHODS: Consecutive patients were evaluated as part of the I-NODAL study (Investigation of Nodal Osteoarthritis to Detect an Association with Loci encoding Interleukin-1 [IL-1]). Evaluation included a physical examination by a trained rheumatologist, a postero-anterior radiograph of the hands, and a digital photograph of each hand. Radiographs were read by one trained observer using the Kellgren-Lawrence scale. Photographs were taken by one individual and were analyzed by an experienced rheumatologist. Kappa statistics were determined for each modality and accuracy was assessed using radiographic readings as a gold standard. RESULTS: Intra-reader reliability for radiograph interpretation was good for the overall diagnosis of hand OA (kappa0.76 [0.45,1.07]), but varied widely for the presence or absence of K-L grades 2-4 in individual joints (median kappa0.70, range 0.49-0.87 for ACR index joints). Distal interphalangeal joint (DIP) nodes on physical examination were sensitive (median 96.27, 93.94-100), but not specific for radiographic hand OA in the corresponding joint (median 33.0, 17.24-42.86). Physical examination evidence of OA in the 1st carpo-metacarpal (CMC) and proximal interphalangeal (PIP) joints provided only moderate sensitivity and specificity. However, the negative predictive value of the examination of individual joints was good (median negative predictive value was 82.58 for IP joints with a range 68.29-100.00), particularly in the DIP joints. Specificity of a node visualized on hand photograph was variable (median for all IP joints and 1st CMC 83.77, range 53.37-96.97), with greatest specificity for radiographic OA in the corresponding joint found in the 1st CMC and the PIP joints. Clinical hand OA was sensitive, but not specific for the radiographic diagnosis of hand OA; while, photographic OA was moderately specific, but insensitive. CONCLUSION: The visualization of a node on a digital photograph of the hand provides fair to moderate specificity for radiographic hand OA in the corresponding joint, with generally poor sensitivity. A photograph has limited value as a screening tool for the diagnosis of radiographic hand OA.

Association of erosive hand osteoarthritis with a single nucleotide polymorphism on the gene encoding interleukin-1 beta.

OBJECTIVE: Certain forms of primary osteoarthritis (OA), particularly those affecting hand joints, have a genetic component. Recent studies have shown suggestive evidence that hand and knee OA are linked with the interleukin-1 (IL-1) region on human chromosome 2q. This study was undertaken to assess the association of primary OA of the hand (hand OA) with IL-1 region markers. METHODS: Sixty-eight US Caucasoid cases and 51 US Caucasoid controls aged 60 years or older were recruited from the Mid-Atlantic region of the United States. Hand OA was classified by American College of Rheumatology (ACR) Clinical Criteria, and cases were subjected to radiographic examination for subgrouping. Genotyping was done for seven previously described single nucleotide polymorphisms (SNPs) of genes for IL-1alpha (encoded by IL1A), IL-1beta (IL1B), and the IL-1 receptor antagonist (IL1RN), as well as an IL1RN variable number of tandem repeat (VNTR) marker. Six microsatellite markers on other chromosomes (null loci) were also typed. RESULTS: The IL1B 5810 G>A SNP genotypes marker were not in Hardy-Weinberg equilibrium (p<0.05 in both non-erosive and erosive hand OA subgroups). Statistically significant association with the IL1B 5810 AA genotype was found in the erosive hand OA subgroup (relative risk 3.8, p=0.007). This IL1B 5810 AA genotype association was also significant between erosive and non-erosive hand OA subjects (relative risk 4.01, p=0.008). As expected, significant linkage disequilibrium was present between IL1B 5810 SNP and IL1A (-)889 SNP, other IL1B SNPs, and the nearest IL1RN SNP examined. The IL1B 5810A allele occurs most frequently on haplotypes with the SNP alleles IL1B 1423C, IL1B 1903T, IL1B 5887C, and IL1A (-)889C. Genotypes at null loci failed to show evidence suggesting population stratification that might account for spurious association. CONCLUSION: Statistical evidence shows association between erosive hand OA and a genomic region containing the IL1B 5810 SNP in a US Caucasoid population. This supports a potential role for IL-1 in the pathogenesis of a severe phenotype of hand OA.

RAGE and arthritis: the G82S polymorphism amplifies the inflammatory response.

The receptor for advanced glycation end products (RAGE) and its proinflammatory S100/calgranulin ligands are enriched in joints of subjects with rheumatoid arthritis (RA) and amplify the immune/inflammatory response. In a model of inflammatory arthritis, blockade of RAGE in mice immunized and challenged with bovine type II collagen suppressed clinical and histologic evidence of arthritis, in parallel with diminished levels of TNF-alpha, IL-6, and matrix metalloproteinases (MMP) 3, 9 and 13 in affected tissues. Allelic variation within key domains of RAGE may influence these proinflammatory mechanisms, thereby predisposing individuals to heightened inflammatory responses. A polymorphism of the RAGE gene within the ligand-binding domain of the receptor has been identified, consisting of a glycine to serine change at position 82. Cells bearing the RAGE 82S allele displayed enhanced binding and cytokine/MMP generation following ligation by a prototypic S100/calgranulin compared with cells expressing the RAGE 82G allele. In human subjects, a case-control study demonstrated an increased prevalence of the 82S allele in patients with RA compared with control subjects. These data suggest that RAGE 82S upregulates the inflammatory response upon engagement of S100/calgranulins, and, thereby, may contribute to enhanced proinflammatory mechanisms in immune/inflammatory diseases.

Tumor necrosis factor markers show sex-influenced association with rheumatoid arthritis.

OBJECTIVE: The observation that not all shared-epitope genotypes confer the same risk suggests that a second HLA-region locus may confer risk. Tumor necrosis factor alpha (TNFgamma) is a possible candidate. We examined TNFalpha for sex influences on HLA-associated risk for rheumatoid arthritis (RA). METHODS: DRB1 and TNF microsatellite typing of 297 Caucasian RA patients (132 men, 165 women) and 267 Caucasian controls was performed. RESULTS: The TNFab microsatellite haplotype distribution differed among the male RA, female RA, and control groups (P < 0.01); the difference was largely an excess of TNFa2b1 haplotypes in the male RA group. However, this did not simply reflect an excess of shared-epitope haplotypes bearing TNFa2b1. In RA, not all shared-epitope-bearing haplotypes had the same TNFab. The *0401-bearing haplotypes commonly had TNFa6b5, TNFa2b1, TNFa10b4, and TNFa11b4, while the *0404-bearing haplotypes had TNFa11b4. In the female RA group, TNFa2b1 was most often on *0401-bearing haplotypes. In the male RA group, there was a surprise: TNFa2b1 was often on HLA haplotypes without shared-epitope DRB1 alleles. To estimate the relative strength of associated HLA markers, we performed logistic regression analyses stratified by sex and controlling for a potential confounder, age at disease onset. Among women, TNFa2b3 favored RA (odds ratio 1.932, P < 0.05) while TNFa6b5 was protective (odds ratio 0.522, P < 0.05). Among males, TNFa2b1 and TNFa11b4 conferred elevated odds ratios (2.58 and 1.681, respectively, P < 0.05). However, the odds ratios for TNFa2b1 in men and TNFa2b3 in women were generally well below those for RA-associated DRB1 markers (for example, DRB1*0401 3.553 in male RA patients and 6.991 in female RA patients). CONCLUSION: Certain TNFab-bearing HLA haplotypes modify RA risk in a manner influenced by sex but independent of DRB1, particularly TNFa2b1 in men.

HLA DMA and DMB show no association with rheumatoid arthritis in US Caucasians.

HLA DM is a heterodimeric molecule functioning in normal antigen presentation; it is encoded by adjacent HLA-region loci, HLA DMA and DMB, located between DP and DQ. Some previous studies have suggested that HLA susceptibility to rheumatoid arthritis (RA) is associated with certain DMA and DMB alleles. Our aim was to examine whether this association is also present in US Caucasians. We studied 288 US Caucasian subjects with rheumatoid arthritis and 263 US Caucasian control subjects. DMA and DMB typing was achieved by PCR amplification followed by sequence-specific oligonucleotide hybridization and by PCR-restriction fragment length polymorphism. There was no frequency difference for DMA alleles or DMB alleles between RA and control subjects, indicating no association. Neither was a difference apparent when data were analysed in subgroups based on shared-epitope DRB1, on the rheumatoid factor test, on radiographic changes of RA, or on sex. DRB1-DQB1-DMB analyses for linkage disequilibrium showed that the DRB1*0401-DQB1*0301 haplotype had the DMB*0103 allele more often than DMB*0101 (estimated haplotype frequencies 0.08 and 0.039 in RA, respectively). In contrast, the DRB1 *0401-DQB1 *0302 haplotype usually had the DMB*0101 allele (haplotype frequency 0.084 compared to 0.01 for DMB*0103). Thus, neither HLA DMA nor DMB was associated with RA in this population, and not all shared-epitope-bearing haplotypes had the same DMB allele distribution.

Tumor necrosis factor microsatellite markers TNFa5b5 and TNFa6b5 influence adverse reactions to parenteral gold in Caucasians.

OBJECTIVE: To investigate which HLA haplotypes identified by DRB1 or tumor necrosis factor (TNF) microsatellite markers are associated with adverse reactions to parenteral gold injections. METHODS: We retrospectively studied 193 Caucasian subjects with rheumatoid arthritis (RA) who had received parenteral gold injections from a university faculty outpatient practice (n = 163) and outpatient clinics at a Department of Veterans Affairs Medical Center (n = 30). DRB1 typing was done by several DNA based techniques. TNF microsatellite genotypes were derived by polymerase chain reaction amplification, sequencing-type gel electrophoresis, and silver staining. RESULTS: Seventy-six subjects had experienced adverse reactions to gold injections (other than nitritoid reactions), 18 of whom had 2 concurrent toxicities. The numbers with adverse reactions included: mucocutaneous (57), proteinuria (25), hematuria without proteinuria (5), thrombocytopenia (3), and miscellaneous (11). By frequency comparisons, no DR was associated with adverse reactions to parenteral gold (chi-squared 4.7, 6 df, NS). Specifically, there was no increased risk of proteinuria or mucocutaneous side effects in the DR3 positive RA group, almost all of whom had the DRB1 allele *0301. By logistic regression modeling controlling for sex and onset age, DR12 and the TNF microsatellite markers a5b5 and a6b5 were associated with mucocutaneous reactions (p < 0.05 for each). The odds ratios favoring mucocutaneous adverse reactions were 3.72 with TNFa5b5 and 2.03 with TNFa6b5. TNFa5b5 was commonly found on the HLA haplotypes bearing DRB1*0101, and TNFa6b5 was on the ones bearing DRB1 alleles of the DR1, DR2, DR3, DR5, or DR6 groups or the DRB1*0401 allele. CONCLUSION: HLA haplotypes conferring risk of gold induced mucocutaneous reactions were better identified by certain HLA class III markers, namely TNFa5b5 and TNFa6b5, than by any previously associated DR groups.

HLA-DRB1 genotype influences risk for and severity of rheumatoid arthritis.

OBJECTIVE: To examine how HLA-DRB1 genotypes influence rheumatoid arthritis (RA) risk and clinical severity. METHODS: We performed polymerase chain reaction based DRB1 and tumor necrosis factor (TNF) genotyping of 309 Caucasian RA and 283 Caucasian control subjects. For risk analyses, we grouped the DRB1 alleles encoding each specific shared epitope: *0401 alone, *0404 with *0102, *0405 with *0408 and *0101, and *1001 alone. For estimates of RA outcome, we retrospectively obtained data regarding ARA classification criteria, age of disease onset and disease duration, number of slow acting antirheumatic drugs (SAARD) used, and rheumatoid factor (RF). RESULTS: Homozygous shared-epitope DRB1 genotypes, compound heterozygous genotypes, and simple heterozygous genotypes all conferred elevated relative risk (RR) for RA (RR 4.3, 11.7, and 3.5, respectively). However, compound heterozygous genotypes conferred more risk than either simple heterozygous genotype (RR 3.3, p = 0.004) or homozygous genotype (RR 2.8, p = 0.036). There was a trend toward more compound heterozygous genotypes in the male RA group than in the female RA group (p < 0.1), and male sex was associated with higher frequency of rheumatoid nodules (56 vs 35% for female RA). RA outcome was estimated by number of SAARD used; mean SAARD used was higher in male than in female RA (p < 0.01) and higher in genotypes containing one or 2 shared epitope DRB1 alleles than in those negative for shared epitope DRB1 alleles (p < 0.05). Analyses also suggested that shared epitope DRB1 genotype significantly influenced the occurrence of seropositive RA. Seropositive RA fraction was related to either number of shared epitope alleles (0, 1, or 2) represented in the DRB1 genotype, or, alternatively, to the combination of sex with shared epitope DRB1 genotype. The presence of one or 2 shared epitope DRB alleles influenced the occurrence of high titer seropositive RA as defined by sheep cell agglutination test (p < 0.01). TNFab microsatellite markers and TNF promoter polymorphisms did not influence SAARD number, seropositive RA, or high titer seropositive RA. CONCLUSION: Not all shared epitope DRB1 genotypes conferred the same relative risk, and the male RA group tended to have more compound heterozygous genotypes and more severe RA as indicated by rheumatoid nodules and SAARD usage. DRB1 genotypes with one or 2 shared epitope DRB1 alleles influenced the RA outcome as estimated by numbers of SAARD used and RF.

Sex influences on the penetrance of HLA shared-epitope genotypes for rheumatoid arthritis.

The association between rheumatoid arthritis (RA) and HLA DRB1 alleles may arise through linkage disequilibrium with a disease locus or the direct involvement of HLA alleles in RA. In support of the latter possibility, the shared-epitope hypothesis has been postulated, stating that conformationally similar DR beta chains encoded by several DRB1 alleles confer disease susceptibility. To examine these alternative hypotheses of marker-disease association and to investigate gender differences in RA susceptibility, we analyzed the distributions of PCR-based DRB1 genotypes of 309 Caucasian RA patients and 283 Caucasian controls. Initially, the marker-association-segregation chi 2 method was used to evaluate evidence for linkage disequilibrium and the direct involvement of markers DR4 Dw4, DR4 Dw14, and DR1 in RA susceptibility. Additional shared-epitope models that grouped DRB1 alleles into five classes (*0401, *0404/*0102, *0405/*0408/*0101, *1001, and all others) and postulated relationships between genotypes and RA susceptibility were also fitted to observed genotypic distributions by the method of minimal chi 2. For females, a linkage-disequilibrium model provided a good fit to the data, as did a shared-epitope model with RA most penetrant among individuals with the *0401,*0401 genotype. For males, the best model indicated highest RA penetrance among shared-epitope compound heterozygotes. Clinically, male RA patients had more subcutaneous nodules and greater use of slowly acting antirheumatic drugs, while female RA patients had earlier disease onset. This study therefore suggests that sex-related factors influence the RA penetrance associated with DRB1 shared-epitope genotypes and that DRB1 effects on RA prognosis and pathogenesis should be considered separately for men and women.

B lymphocytic clonal expansion in rheumatoid arthritis.

OBJECTIVE: To learn whether rheumatoid factor (RF), HLA-DR4, or current therapy influences clonal expansion of B lymphocytes (B cells) in persons with rheumatoid arthritis (RA). METHODS: We measured clonal expansion by analysis of cell surface staining for immunoglobulin light chains. Double staining methods detected a B cell marker (CD19) plus either kappa or lambda on peripheral blood lymphocytes from subjects with RA (n = 26) and controls (n = 26). The difference between frequency histograms of surface kappa and lambda staining was determined by the Kolmogorov-Smirnov statistic D that represents the fraction of clonally expanded B cells. RESULTS: The mean D value in RA was over 50% higher than in the controls [0.225 +/- SD 0.155 versus 0.144 +/- 0.025 (p < 0.0001)]. Ten subjects with RA had values exceeding +2 SD for controls (p = 0.0007). Mean D correlated with RF titer (Spearman's rank correlation coefficient rSp + 0.53, p = 0.006). All 10 high D values were found in the RA subgroups with positive serum tests for RF and with the HLA-DR4 positive genotype. The channel of maximal difference between kappa and lambda staining was higher in the RA group than in controls, showing that clonal expansion was most marked among brightly staining cells. Patients with RA currently receiving low dose methotrexate (MTX) tended to have higher D values than those not receiving MTX (mean 0.29 versus 0.18, respectively, p < 0.025). The RA group currently receiving MTX had a higher frequency of abnormal D values (7 of 11 versus 3 of 15 not currently receiving MTX, p = 0.03). This probably reflects preferential use of MTX for severely affected individuals. Confirmatory studies to detect clonal immunoglobulin gene rearrangements were attempted in selected individuals with high D values, but none was demonstrated in total leukocytic or B cell enriched fractions. CONCLUSION: Findings consistent with B cell clonal expansion occur in about 40% of persons with RA, particularly in the subgroups with positive serum tests for RF and with the HLA-DR4 genotype. However, the clonal expansion level must be below the sensitivity of confirmatory methods.

The genotypic distribution of shared-epitope DRB1 alleles suggests a recessive mode of inheritance of the rheumatoid arthritis disease-susceptibility gene.

OBJECTIVE: To test whether the genotypic distribution of rheumatoid arthritis (RA)-associated DRB1 alleles suggests that the DRB1-associated disease-susceptibility gene has a recessive or additive (dominant) mode of inheritance. METHODS: Caucasian patients with RA and control subjects were recruited from a faculty outpatient practice. DRB1 typing was done by several DNA-based techniques: polymerase chain reaction (PCR), followed by dot-blot hybridization with sequence-specific oligonucleotides, conventional and PCR-based restriction fragment length polymorphisms (RFLPs), and a multiplex amplification-refractory mutation RFLP system. The genotypic distribution of shared-epitope DRB1 alleles was analyzed by antigen genotype frequency among patients. The analytical method postulates a linkage-disequilibrium model with a disease locus close to a marker locus and a marker allele in linkage disequilibrium with the disease-susceptibility allele. In this instance, the marker allele was defined alternatively by any DR4-group allele, by any DR4-group or DR1-group allele, by any DR4-group shared-epitope allele, by any DR4-group shared-epitope allele plus DRB1*0101, or by any shared-epitope DRB1 allele. Observed numbers were compared with those predicted for recessive mode or additive (dominant) mode of inheritance of the DRB1-associated RA disease-susceptibility gene. RESULTS: The genotypic distribution of shared-epitope DRB1 alleles (DRB1*0401, *0404, *0405, *0408, *0101, *0102, or *1001) fit that predicted for a recessive mode of inheritance and was significantly different from that predicted for an additive (dominant) mode. When the analysis was restricted to shared-epitope DR4 alleles alone (DRB1*0401, *0404, *0405, or *0408), the observed genotype numbers fit the recessive mode best. When DR1-group alleles were added to DR4-group alleles, or alternatively, when the major shared-epitope DR1 allele (*0101) was added to DR4-group shared-epitope alleles, there was a less significant deviation from the additive mode of inheritance. The reason for this was derived by comparison of observed genotype frequencies to those expected under Hardy-Weinberg equilibrium; there was a deficit of persons with DRB1*0401, *0101 and an excess of *0101,X. CONCLUSION: The genotypic distribution of shared-epitope DRB1 marker alleles suggests that the mode of inheritance of the DRB1-associated disease susceptibility gene must be recessive and not additive (dominant).

Molecular characterization of rat Crry: widespread distribution of two alternative forms of Crry mRNA.

The rat complement regulator 5I2 antigen/Crry is present in a widespread distribution as at least two discrete proteins of Mr 65000-70000 and 75000-85000. The molecular basis for the different proteins has not been determined. We screened a cDNA library derived from cultured rat glomerular epithelial cells with a polymerase chain reaction (PCR)-generated nucleotide probe for CR1 and Crry. Two identical clones with 1.8 kilobase inserts were obtained. Clone 6.1 consisted of 1811 nucleotides. The sequence was identical to nucleotides 42-1666 of the cDNA for rat 5I2 antigen/Crry except for 11 nucleotides at the extreme 5' and 3' ends and an exact duplication of 186 bases that would encode an additional complete short consensus repeat (SCR). By reverse transcription PCR, we show that the two forms of Crry mRNA exist in all rat cells/tissues examined. It is likely that these two Crry mRNA species differ by the absence or presence of a 186 base repeat that encodes a complete SCR. These are translated into Crry proteins, containing six and seven SCRs, respectively, which explains the different sizes of Crry proteins. The role of the SCR duplication remains to be defined.

Systemic lupus erythematosus is not associated with allotypic markers of immunoglobulin kappa in Caucasians.

OBJECTIVE: To determine whether systemic lupus erythematosus (SLE) is associated with a specific Km genotype or allele. Specific genetic markers located both within the major histocompatibility complex (MHC) and outside the MHC have been associated with SLE. However, serologic studies of Km allotypes have led to contradictory results. METHODS: A novel molecular genetic technique was used to determine Km genotypes. First, the kappa constant segment (C kappa) was amplified from genomic DNA by the polymerase chain reaction (PCR). Then the resulting PCR product was subjected to restriction enzyme digestion. AccI cleavage of the C kappa PCR product correlated with Km (3) allotype, and presence or absence of an MaeII site correlated with Km (1) or Km (1, 2), respectively. RESULTS: There was no difference in the distribution of Km genotypes or alleles between Caucasian patients with SLE (n = 26) and controls (n = 107). Clinical features did not differ in 4 Km (1, 2) positive patients with SLE compared to 22 Km (1, 2) negative patients with SLE, nor did the frequency of anti-Sm or antinative DNA autoantibodies (2 Km (1, 2/3) versus 4 Km (3/3); and 1 versus 6, respectively). No Km (1, 2/3) positive individual had anti-La (anti-SSB) autoantibodies. CONCLUSION: Genotypic frequencies of C kappa coding region markers (Km allotypes) do not differ between Caucasian patients with SLE and controls.

Gout attacks in chronic alcoholics occur at lower serum urate levels than in nonalcoholics.

OBJECTIVE: To determine if patients with gout with chronic alcoholism have lower serum urate levels than nonalcoholic patients. METHODS: Of 95 consecutive consults for acute gout at a VA medical center, 42 were excluded from study due to lack of crystal documentation, lack of urate value within 2 years, or treatment with allopurinol or probenecid. The remaining 53 patients were grouped by alcohol use and a retrospective chart review was done for these patients. RESULTS: Mean intercritical serum urate values for chronic alcoholics and nonalcoholics were similar at 9.7 +/- 2.1 for alcoholics and 9.5 +/- 2.1 for nonalcoholics. Yet, despite these similar intercritical serum urate values, and despite no difference between chronic alcoholics and nonalcoholics in frequency or severity of acute gout flares, patients with chronic alcoholism had index serum urate levels which were significantly lower than those of nonalcoholics. These mean index values, with standard deviations, were 7.7 +/- 1.3 for 15 chronic alcoholics and 10.1 +/- 1.3 for 34 nonalcoholics; p < 0.01). CONCLUSION: Alcoholics and nonalcoholics had comparable intercritical values. However, on presentation with acute arthritis, the index serum urate values for alcoholics were lower than in nonalcoholics. Values for serum urate below 8.5 mg/dl are of less value in excluding gout in chronic alcoholics than in nonalcoholics presenting with acute gout flares.

Polymerase chain reaction-based genotyping for allotypic markers of immunoglobulin kappa shows allelic association of Km with kappa variable segment.

Allotypic markers of immunoglobulin kappa (Km) may be determined using a novel method of amplification of the constant segment (C kappa) (IGKC) by polymerase chain reaction (PCR) followed by restriction enzyme digestion. Restriction sites in the C kappa PCR product correlate with allotypic differences among Km(1), Km(1,2), and Km(3) alleles. An AccI site in the PCR product correlates with Km(3); and presence or absence of a MaeII site correlates with the Km(1) or Km(1,2) allele, respectively. Km allelic frequencies were determined in a Caucasian population and compared to genotypic frequencies of nearby polymorphic markers. Among unrelated individuals with rheumatoid arthritis (RA) and controls, there is no evidence of allelic association between CD8A and polymorphic markers of the immunoglobulin kappa region [a V kappa (IGKV) BglII polymorphism about 24 kb centromeric to C kappa, Km allotype, and a SacI polymorphism 3.5 kb telomeric to the C kappa segment]. Similarly, there is no allelic association of the SacI C kappa polymorphism with Km or with the BglII V kappa polymorphism. However, there is evidence of allelic association of V kappa B3 and Km, specifically between the V kappa BglII 2.2-kb allele and Km(3) and also between the V kappa 3.5-kb allele and Km(1,2). Therefore, Km typing by PCR-based methods suggests the presence of allelic association between polymorphisms within the coding region of the C kappa segment and the nearest V kappa segment.

Variable-constant segment genotype of immunoglobulin kappa is associated with increased risk for rheumatoid arthritis.

OBJECTIVE: To further investigate the association of rheumatoid arthritis (RA) with a particular genotype identified by a restriction site polymorphism near the constant segment of immunoglobulin kappa (C kappa). METHODS: The frequencies of genomic DNA polymorphisms detected within or near C kappa (the most C kappa-proximal variable segment [V kappa] B3 and a T lymphocyte marker [CD8A]) were determined by Southern blotting and hybridization. The frequencies of coding-region polymorphisms of C kappa (Km allotypes) were determined by amplification by polymerase chain reaction followed by restriction enzyme digestion. RESULTS: Although the frequencies of B3, Km, and CD8A genotypes were not different between RA and normal control populations, more individuals were homozygous for both C kappa and B3 in the RA group (relative risk 2.2, P less than 0.01), especially in the DR4-negative RA subgroup (relative risk 3.9, P less than 0.001). CONCLUSION: The homozygous genotype of an approximately 30,000-base region including the C kappa segment confers an elevated risk for RA, particularly in the DR4-negative subgroup.

Synovial fluid levels of complement SC5b-9 and fragment Bb are elevated in patients with rheumatoid arthritis.

To determine whether complement turnover in synovial fluids of patients with rheumatoid arthritis (RA) reflects activation by the classical or alternative pathway, we used novel immunoassays to measure products of complement activation (the membrane attack complex SC5b-9 and the cleavage fragments Bb and C4d). Mean synovial fluid levels of SC5b-9 were more than 8 times higher in RA than in crystal-induced arthritis (gout and pseudogout) and over 16 times higher than in degenerative joint disease (DJD). Similarly, Bb levels were more than 3 times higher in RA synovial fluids than in crystal-induced arthritis and over 7 times higher than in DJD. Levels of C4d did not differ among the groups. SC5b-9 levels correlated with synovial fluid C3 anaphylatoxin (C3a), Bb, and C4d levels (r = 0.81, 0.62, and 0.51, respectively). In patients with RA, synovial fluid SC5b-9 levels correlated with C3a and Bb (r = 0.6 and 0.56, respectively) but not with C4d. Therefore, novel assays for complement activation indicate that both classical and alternative pathways are involved in complement turnover and that the alternative pathway contributes more to complement activation in RA than in DJD or crystal-induced arthritis.