Linkage of HLA-DR beta specific restriction fragment length polymorphisms with Graves' disease

HLA-DR3 positive patients with Graves' disease (6 homozygotes, 7 heterozygotes, i.e. yielding 19 haplotypes) were studied by restriction fragment length polymorphism analysis using TaqI as restriction enzyme in order to look for polymorphisms in the HLA-DR3 allele of the human major histocompatibility complex. Polymorphic TaqI fragments of 11.6, 9.8 and 5.8 kb, each corresponding to HLA-DR beta sequences, were shown to differ in their prevalence in patients with Graves' disease and controls. The prevalence of DR3 polymorphisms in a total of 35 HLA-DR3-containing haplotypes was markedly different within patients with Graves' disease and Caucasian controls. Whereas a 11.6 kb fragment was rare in Graves' disease (2/19 haplotypes vs 8/16 in controls), the inverse ratio was found for a 9.8 kb fragment, with a prevalence of 17/19 and 8/16 haplotypes, respectively. A polymorphic fragment of 5.8 kb was exclusively seen in two DR3-containing haplotypes of patients with Graves' disease. Our data provide evidence that a DNA polymorphism of the HLA-DR beta genes, which is also reflected at the product level, is linked to Graves' disease.     

DNA restriction fragment length polymorphism of HLA-DR2 haplotypes in normal individuals and in patients with rheumatoid arthritis.

A strong association between HLA-DR4 and rheumatoid arthritis (RA) has been found in a number of populations. In contrast, the incidence of DR2 is decreased in patients with RA, suggesting that this specificity may confer some protection against the disease. A number of subtypes of DR2 have been defined by serology, by responses in mixed lymphocyte culture reaction, and, more recently, by restriction fragment length polymorphism. These subtypes of DR2 are in linkage disequilibrium with different subspecificities of DQw1. It is thus likely that the distribution of these subtypic DR,DQ haplotypes in DR2 positive patients with RA may be important in understanding the genetic basis of susceptibility/resistance to RA. In this paper a study of the subtypes of DR2,DQw1 haplotypes in 18 patients with RA, who required sodium aurothiomalate as a disease remitting drug, and unrelated healthy individuals is reported. Three subtypes of DR2 haplotypes, DRw15 (Dw2),DQw1.2(DQw6), DRw15(Dw12),DQw1.12(DQw6), and DRw16(Dw21),DQw1, AZH (DQw5), were analysed with a cDNA probe for the DQ beta gene. The data show that DR2 positive patients with RA carried either the DRw15(Dw2),DQw6 or DRw15(Dw12),DQw6 haplotype. No patient with RA was positive for the DRw16(Dw21),DQw5 subspecificity. In contrast, six of 29 (21%) normal healthy DR2,DQw1 positive individuals carried the DRw16(Dw21),DQw5 haplotype. These data together with earlier results on the distribution of the DR4,DQw7 haplotype in patients with RA support the hypothesis that DQB1 chain polymorphism may be important in determining susceptibility to severe RA.     

Identification of a polymorphic variant associated with HLA-DQw3 and characterized by specific restriction sites within the DQ beta-chain gene.

Restriction endonuclease digestion of genomic DNA from 24 lymphoblastoid cell lines homozygous for the HLA class II specificity DQw3, followed by hybridization with a DQ beta-chain cDNA probe, identified a genomic polymorphism with variable BamHI and HindIII recognition sites. This restriction fragment pattern was found for several haplotypes associated with the DQw3 specificity, including some haplotypes positive for the HLA-DR specificities DR4, DR5, DRw8, and DRw12. The variant fragment pattern corresponds precisely with the reactivity of a monoclonal antibody, A-10-83, previously shown to define a serologic split of DQw3. Serologic detection of the specific DQw3.1 genomic polymorphism indicated that the corresponding DQ beta-chain variants are expressed. This polymorphic restriction fragment pattern, then, represents a selective marker for DQ beta-chain genes that appear to define a DQ beta-chain-associated specificity, here called DQw3.1.     

HLA-DQ-RELATED RESTRICTION FRAGMENT LENGTH POLYMORPHISMS IN RHEUMATOID ARTHRITIS: EVIDENCE FOR A LINK WITH DISEASE EXPRESSION

Eighty-three patients with rheumatoid arthritis (RA) were investigatedfor HLA-DQ and DR locus restriction fragment length polymorphisms(RFLP). Of the 83 patients, 61 (73%) possessed the DR4 alleleand within this group we have investigated the relative frequenciesof two DQ beta gene variants of DQw3, DQw7 and DQw8, one ofwhich we had previously found to be raised in Felty's syndrome.This analysis revealed a significantly higher frequency of DQw7containing haplotypes in DR4 positive rheumatoid patients (64%)than in DR-matched healthy controls (42%). Furthermore, thedistribution of DQw7 was biased towards those patients withgreater disability indicated by the HAQ score, more systemicdisease and higher titres of rheumatoid factor, suggesting thatDQw7 may contribute to disease expression. KEY WORDS: HLA system, Disease association, Rheumatoid factor     

Novel genetic markers of rheumatoid arthritis in Chilean patients, by DR serotyping and restriction fragment length polymorphism analysis.

OBJECTIVE. The analysis of genetic markers of rheumatoid arthritis (RA) in a population in which the DR4 serotype is not strongly associated with the disease. METHODS. Chilean RA patients (56 seropositive and 22 seronegative) and 141 controls were studied by serotyping. Southern blot analysis of Bam HI restriction fragment length polymorphism (RFLP) was done in genomic DNA from 46 patients with seropositive RA, 17 patients with seronegative RA, and 45 controls, using a complementary DNA probe specific for DRB1 genes. RESULTS. The prevalence of the HLA-DR9 haplotype was strikingly higher in seropositive RA patients (21%) than in controls (3%) (Pcorr less than 0.0008, by Fisher's exact test; relative risk [RR] = 9.34). The prevalence of DR4 and DR1 haplotypes, although slightly increased, did not achieve a significant preponderance. The simultaneous presence of two Bam HI fragments (3.6 kb and 4.5 kb) was found with higher prevalence in seropositive patients (83%; RR = 9; Pcorr less than 0.00002) than in controls (36%), and seemed higher in seronegative RA patients as well (71%; RR = 4). Furthermore, its prevalence remained increased in comparisons of DR4 positive controls (36%) with DR4 positive seropositive patients (100%; RR = 67; Pcorr less than 0.0002) and DR4 positive seronegative patients (100%; RR = 36; Pcorr less than 0.006), even after excluding the DR9 positive individuals. A tendency toward higher association with DR1 seropositive RA patients (67%; RR = 12), a group with no DR4 or DR9 positive individuals, than in DR1 positive controls (14%), was also observed. CONCLUSION. The HLA-DR9 haplotype was definitively consolidated as a very strong genetic marker exclusively for seropositive RA in Chilean patients, as suggested by our previous observations. RFLP analysis showed that the simultaneous presence of 3.6-kb and 4.5-kb Bam HI fragments constituted a better RA marker than did any of the heretofore studied haplotypes. These fragments together would be linked to RA independently of the DR1, DR4, and DR9 haplotypes. The overall evidence indicates that Chilean seropositive RA patients display a genetic background that is different from that underlying RA susceptibility in other populations and suggests the existence of common, as well as distinct, genetic elements predisposing to seronegative and seropositive RA.     

A variant of HLA-DR4 determines susceptibility to rheumatoid arthritis in a subset of Israeli Jews

HLA-DR4 is associated with risk for developing rheumatoid arthritis (RA) in most populations. In Israeli Jews, in whom the Dw10 subtype of DR4 predominates, no association of RA with DR4 has been found. The inability to detect an association could be due to the high frequency of DR4-Dw10. We used DNA typing with amplification by the polymerase chain reaction and dot-blotting with allele-specific oligonucleotides to determine DR4 variants in 131 Jewish RA patients living in Israel and 134 controls. In both Ashkenazi Jews and non-Ashkenazi Jews, the rare variant Dw15 (previously identified in Japanese populations and in Japanese patients with RA) was found to be the main allele associated with the risk of developing RA (relative risk = 9.2, corrected P less than 0.001). However, this low-frequency allele could be responsible for susceptibility in only 11.5% of the patients. Susceptibility for rheumatoid factor-positive RA was associated with Dw4 and Dw15; the risk for rheumatoid factor-negative RA was associated only with Dw14. The distribution of the HLA-DQ alleles associated with DR4 showed that more than half of the RA patients with Dw15 also had HLA-DQw2. The frequencies of DQw7 and DQw8 were not different in RA patients compared with controls. The results suggest that, as in other populations, susceptibility for the development of RA in Israeli Jews is associated with DRB1 locus alleles of the DR4 group.     

Restriction fragment length polymorphism analysis of HLA-DR, DQ, DP and C4 alleles in Caucasians with systemic lupus erythematosus.

HLA-DR, DQ, DP and C4 null alleles were determined by restriction fragment length polymorphism (RFLP) analysis in 60 Caucasian patients with systemic lupus erythematosus (SLE) and 66 controls. DR3 (DRw17) and DQw2.1 were increased in frequency in the patients with SLE associated with the presence of C4A null genes. HLA-DP alleles determined by RFLP analysis of genomic DNA as well as of PCR amplified DNA were not associated with SLE or any clinical or autoantibody subset thereof. No DR, DQ, or C4 null gene association was found with renal or neuropsychiatric involvement or nDNA antibodies (or levels thereof). These data suggest that the primary predisposition to SLE lies with HLA-DR or C4 null alleles, and not with HLA-DP.     

DNA analysis of HLA-DR, DQ and DP genes in pauciarticular juvenile rheumatoid arthritis.

HLA-DR, DQ, and DP alleles were determined by restriction fragment length polymorphism (RFLP) and oligonucleotide hybridization analysis in 50 Caucasian children with pauciarticular juvenile rheumatoid arthritis (PaJRA) and 82 controls. There was an increased frequency of DR5, DRw8, and DQw4, as well as individual DQ alpha and beta chains, DQA*0401 and DQB1*0402, respectively, in this group of patients. There was an absolute association between DRw8, DQw4, DQA1*0401, and DQB1*0402 in the patient population. HLA-DPw2.1 was also increased in frequency. There was little evidence of linkage disequilibrium found between DPw2.1 and DR5, DRw8, or DQw4. These MHC Class II associations were more characteristic of those patients with young age of onset (less than 5 years), rather than those with onset greater than or equal to 5 years of age. Our data confirmed the previous associations of HLA-DR5, DRw8, and DPw2.1 with PaJRA and suggested a new association for DQ alpha and beta genes in the clinical expression of this disease.     

Detection of disease-specific restriction fragment length polymorphisms in pemphigus vulgaris linked to the DQw1 and DQw3 alleles of the HLA-D region

Pemphigus vulgaris in Israeli Ashkenazi and non-Ashkenazi Jews and in Austrian non-Jewish patients is strongly associated with the DR4 and DRw6 alleles of the HLA-D region class II genes. Restriction fragment length polymorphism analysis was undertaken with DQ beta, DQ alpha, and DR beta cDNA probes. Hybridization with the DQ beta probe identifies Pvu II, BamHI, and EcoRV fragments that absolutely discriminate pemphigus vulgaris patients from healthy DR-, DQ-, and ethnic-matched controls. In contrast the DQ alpha and DR beta probes failed to identify disease-specific restriction fragment length polymorphism fragments. These studies indicate that DQw1 and DQw3 polymorphisms carried by pemphigus vulgaris patients may be directly involved in predisposition to the disease or may be tightly linked to the susceptibility gene itself. To our knowledge, this is the first example of an HLA restriction fragment length polymorphism that is highly associated with susceptibility to autoimmune disease.     

Linkage between rheumatoid arthritis susceptibility and the presence of HLA-DR4 and DR beta allelic third hypervariable region sequences in southern Chinese persons.

OBJECTIVE. To analyze HLA-DR and DQ associations with rheumatoid arthritis (RA) in patients from southern China. METHODS. In 66 patients and 45 controls, restriction fragment length polymorphism studies were performed using DRB, DQA, and DQB probes, and DRB allele-specific typing of polymerase chain reaction-amplified DRB DNA. RESULTS. The frequency of HLA-DR4 was significantly increased among RA patients (42.4% versus 17.8%). Increased frequencies of the DQA3 allele (77.8% versus 48.9%) and the DQB1*0302 allele (71.0% versus 46.3%), which are in linkage disequilibrium with DR4, were also found. Oligonucleotide typing showed that the amino acid sequence LLEQRRAA, spanning amino acid positions 67-74 of the DR beta molecule, was found in 19 of 49 patients and 5 of 32 controls. The main DR4 allelic subtypes found in the population were DRB1*0404 and DRB1*0405, both of which carried the sequence. There was no difference in subtype distribution between patients and controls. CONCLUSION. Chinese RA patients have an increased frequency of HLA-DR4 alleles which possess the same DRB third allelic hypervariable sequence shown to be associated with susceptibility in Caucasian RA patients.     

DNA analysis of HLA-DR and DQ genes in American blacks with systemic lupus erythematosus

We studied DNA polymorphisms of HLA-DR and DQ alleles in 63 American black patients with systemic lupus erythematosus (SLE). We found no HLA-DR beta, DQ alpha, or DQ beta restriction fragment length polymorphism (RFLP) or RFLP-determined DR or DQ specificity associated with SLE in either the patients or in 57 control subjects. DRw52b was positively associated with renal involvement and negatively associated with anti-nuclear RNP antibodies. Antibodies to Ro (SS-A) and La (SS-B) were associated with DR3(DRw17), DQw2.3. Early-onset SLE (less than or equal to 20 years of age) was associated with DRw8, and the frequency of neuropsychiatric involvement correlated negatively with a 3.7-kb Taq I DQ alpha RFLP. This suggests a role for DR and DQ genes in the clinical and serologic expression of SLE in American blacks.     

IMMUNOGENETICS OF GRAVES'' OPHTHALMOPATHY

We have performed an immunogenetic analysis of 53 patients with severe Graves' ophthalmopathy, 51 patients with Graves' disease but little or no clinically apparent eye disease, and 90 controls. The distribution of restriction fragment length polymorphisms was analysed in the three groups, using probes for the HLA-DQ alpha and DR beta regions, the T-cell receptor C alpha, V alpha, C beta and J gamma genes and the immunoglobulin gene switch regions, S alpha and S mu. There was no abnormal distribution of these polymorphisms in either group of Graves' patients, or differences between the Graves' patients with or without eye disease. It was possible to assign HLA-DR types in most patients using the polymorphisms found after probing with DQ alpha and DR beta; there was no abnormal distribution of DR types (including HLA-DR3) assigned by restriction fragment polymorphisms in the two Graves' groups. These results fail to confirm the reported associations between ophthalmopathy and HLA-DR3 and between Graves' disease and the T-cell receptor C beta polymorphism; they also argue against a strong influence of Gm allotypes in Graves' disease since these genes are in linkage disequilibrium with the S alpha polymorphisms. The association of Graves' disease with HLA-DR3, defined hitherto using serological reagents, may be less strong than previously described.     

HLA-DR alleles with naturally occurring amino acid substitutions and risk for development of rheumatoid arthritis

To determine the HLA-DR4 subtypes associated with rheumatoid arthritis (RA), we performed amplification of DR4 DRB1 genes by the polymerase chain reaction and dot-blots with oligonucleotide probes. In 52 HLA-DR4+ RA patients, Dw4 was the predominant subtype. This subtype was found in 45 of 52 patients (86.5%) compared with 33 of 59 DR4+ controls (55.9%; P less than 0.001). In the whole population, Dw4 also gave the highest relative risk for RA (RR = 5.31). Relative risk was also associated with DR1.1, the common white DR1 (Dw1) type, which has a third hypervariable region amino acid sequence similar to some forms of DR4 and has glycine at position 86. Variants of DR1 (DR1.2) or DR4 (Dw13.1, Dw14.1) with valine at position 86 appeared less able to confer risk for RA. Substitution of residues in the third hypervariable region of the first domain of DRB1 appeared to correlate with relative risk for RA. Among subjects having 0-1 amino acid substitutions, RA developed in 53%, whereas in subjects with 2-4 amino acid changes, RA was present in only 17.4% (P less than 0.00001). DQw7 (formerly DQw3.1) was slightly increased in DR4+ RA patients compared with controls, but a striking excess of Dw4,DQw7 homozygous patients was observed. The results suggest that DQw7 may have an additional effect, possibly with a recessive mechanism, since it was observed only in DR4 homozygous patients.     

Structural analysis of the HLA-DR, -DQ, and -DP alleles on the celiac disease-associated HLA-DR3 (DRw17) haplotype

Celiac disease is strongly associated with the HLA class II D-region serologic markers DR3 (DRw17) and DQw2. Moreover, by restriction fragment length polymorphism analysis, greater than 90% of DR3 (DRw17), DQw2 celiac disease patients have a polymorphic 4.0-kilobase Rsa I DP B gene DNA fragment. The present study sought to determine if there is a unique HLA class II D-region A or B gene structural variant on the DR3 (DRw17) haplotype found in celiac disease. The polymorphic second exons of the coding DRB, DQA and DQB, and DPA and DPB genes in celiac disease patients with the DR3 (DRw17) haplotype were sequenced after amplification by the polymerase chain reaction. To define the DP B genes associated with celiac disease, the second exons of the coding DP B genes from 27 celiac disease patients were amplified similarly and probed by using a panel of sequence specific oligonucleotides. The HLA-DR, -DQ, and -DP A and B gene second exon sequences of celiac disease patients were noted to be identical to sequences that can be found also, although at a significantly lower frequency, in unaffected individuals. This is compatible with a disease model wherein the HLA class II genes on the DR3 (DRw17) haplotype are necessary, but not sufficient, for the phenotypic expression of celiac disease. Analysis of the DP B genes revealed a significant increase in the frequency of the alleles DPB1 and DPB3 in celiac disease. Furthermore, the increased frequency of the 4.0-kilobase Rsa I DP B gene restriction fragment length polymorphism in celiac disease can be accounted for by the overrepresentation in disease of the alleles DPB1 and DPB3. The HLA-associated susceptibility to celiac disease appears to be multigenic, with specific, but structurally normal, allelic variants in the DP and DQ/DR subregions contributing to disease susceptibility.     

Association of DQw7 (DQB1*0301) with ocular cicatricial pemphigoid.

Ocular cicatricial pemphigoid (OCP) is an autoimmune blistering disease that affects the conjunctiva and multiple mucous membranes. Class I and II and complement genetic markers of the major histocompatibility complex were studied in 20 Caucasian OCP patients and members of their families. Frequencies of individual alleles and common fixed or extended haplotypes in the patients were compared with those in normal family control haplotypes and with overall normal Caucasian haplotypes. The most striking increase compared with overall controls was noted in HLA-DQw3 (P = 0.006), unassociated with any extended haplotype. All but 1 of the 20 patients carried DQw3 in linkage with HLA-DR4 (increased significantly with P = 0.042 compared with overall normal genotype controls) or DR5. The DQw3, on analysis by restriction fragment length polymorphism in genomic DNA, was, in every instance, DQw7 (3.1, DQB1*0301). The frequency of DQB1*0301 in patient haplotypes compared with overall normal DR4 and DR5 DQw3-bearing haplotypes was statistically significantly increased (P less than 0.003, relative risk = 9.6). The distribution of homozygotes and heterozygotes for DQB1*0301 among the patients was consistent with dominant but not recessive inheritance of DQB1*0301 or a gene, probably a class II allele, in linkage disequilibrium with it as the major histocompatibility complex susceptibility gene for OCP.     

HLA haplotypes in Type 1 (insulin-dependent) diabetes mellitus: molecular analysis of the HLA-DQ locus

Summary In Caucasians the predisposition to Type 1 (insulin-dependent) diabetes mellitus has been shown to associate with HLA-DR3,DQw2 and DR4,DQw8 and with the presence of amino acids other than aspartic acid at position 57 on the HLA-DQ chain. In Finland the haplotype-specific absolute risk for developing Type 1 diabetes differs between various DR3 and DR4 positive haplotypes. The aim of our present analysis was to find out whether this variation is attributable to polymorphism at the DQ locus. As part of a nationwide prospective study including 757 serologically HLA genotyped families, we determined HLA-DQ and DQ restriction fragment polymorphisms in 17 selected families with important susceptibility haplotypes. Additionally, the DQA1 alleles were determined from 19 haplotypes using sequence-specific oligonucleotide probes, and the DQB1 second exon was sequenced from nine haplotypes. The DR3 as well as DR4 positive haplotypes frequently found in Type 1 diabetic patients showed no variation at the HLA-DQ locus, and they were DQw2 and DQw8, respectively. The absolute risk for Type 1 diabetes for DR4,DQw8 positive haplotypes A2,Cw4,Bw35,DR4 A3,Cw3,Bw62,DR4, A24,Cw7,Bw39,DR4, A2,Cw3,Bw62, DR4, and A2,Cw1,Bw56,DR4 was 35/100,000, 130/100,000, 166/100,000, 196/100,000, and 218/100,000, respectively. The absolute risks for DR3,DQw2 positive haplotypes A1, Cw7,B8,DR3 and A2,Cw7,B8,DR3 were 68/100,000 and 103/100,000, respectively. These results provide further evidence that not only the polymorphism at the DQ locus but also other genes of the haplotypes contribute to susceptibility to Type 1 diabetes.     

HLA class II sequence polymorphisms and susceptibility to rheumatoid arthritis in Greeks. The HLA-DR beta shared-epitope hypothesis accounts for the disease in only a minority of Greek patients.

OBJECTIVE. In Northern Europeans, rheumatoid arthritis (RA) is strongly associated with a relatively conserved pentapeptide sequence of HLA-DR beta found notably in the HLA-DR4 subtypes Dw4 and Dw14 and in DR1. A previous serologic study of HLA class II polymorphism in a Greek population with RA failed to show significant associations with any antigen. METHODS. We characterized HLA-DRB polymorphisms in Greek patients with RA and in control subjects by restriction fragment length polymorphism analysis. Allelic DRB subtypes were examined by polymerase chain reaction amplification and oligonucleotide hybridization. RESULTS. DNA analysis in the RA patients showed that although individual HLA-DR allelic associations were weak, a relatively conserved HLA-DR beta motif was significantly associated with RA in this population of Greek patients. The third hypervariable region amino acid sequences QRRAA, QKRAA, or RRRAA were found in the HLA-DR beta 1 of 43.5% of the RA patients versus 15.5% of the controls (uncorrected P = 0.00004). CONCLUSION. Sequences shown to influence susceptibility to RA in patients in the UK also play a role in patients in Greece. However, 57% of Greek patients lack the putative HLA-DR beta motif, which suggests that considerable immunogenetic heterogeneity underlies disease susceptibility in this population.     

HLA class II DR, DQ, and DP restriction fragment length polymorphisms in rheumatoid arthritis.

HLA class II restriction fragment length polymorphisms (RFLPs) were studied in 43 individuals with established seropositive rheumatoid arthritis (RA) and in a group of healthy controls. All patients and controls were tissue typed for HLA-A, B, and DR antigens. Rapid, initial screening for RA associated RFLPs was conducted by pooling DNA samples from 11 HLA-DR4 positive patients with RA and comparing the RFLP patterns with those seen in a pool of DNA samples drawn from 11 HLA-DR4 positive healthy controls. Candidate RA associated RFLPs were examined in our full panel of patients with RA and controls. In most cases the RFLPs detected showed no significant association with RA. An exception was a 13.0 kb DraI DQ beta associated RFLP, which, when HLA-DR4 positive patients with RA and controls were considered alone, showed a weak positive association with susceptibility to RA. This RFLP was not associated with known DR, DQ, or Dw specificities. These results show a distinct paucity of class II RA associated RFLPs but may indicate a role for DQ beta genetic variation in the aetiology of RA.     

Primarily chronic progressive and relapsing/remitting multiple sclerosis: two immunogenetically distinct disease entities

HLA class II gene polymorphism was investigated in 100 patients with clinically definite multiple sclerosis (MS) by restriction fragment length polymorphism analysis of Taq I-digested DNA using DRB, DQA, and DQB cDNA probes. Twenty-six patients had primarily chronic progressive MS and 74 had relapsing/remitting MS. The latter group included patients with a secondary progressive evolution of symptoms. Both clinical forms of MS were found to be associated with the DRw15,DQw6 haplotype. In addition, primarily chronic progressive MS was positively associated with the DQB1 restriction fragment pattern seen in DR4,DQw8, DR7,DQw9, and DRw8, DQw4 haplotypes, as well as negatively associated with the Taq I DQB1 allelic pattern corresponding to the serological specificity DQw7. Relapsing/remitting MS was positively associated with the DQB1 allelic pattern observed in the DRw17,DQw2 haplotype. These three DQB1 alleles are in strong negative linkage disequilibria with DRw15. The two susceptibility markers of each clinical form of MS act additively in determining the genetic susceptibility, as the relative risks for individuals carrying both markers roughly equal the sum of respective risks. Different alleles of the DQB1 locus defined by restriction fragment length polymorphisms contribute to susceptibility and resistance to primarily chronic progressive MS as well as to susceptibility to relapsing/remitting MS. The observed immunogenetic heterogeneity between the different clinical forms of MS favors the hypothesis that primarily chronic progressive MS and relapsing/remitting MS are two distinct disease entities.     

DQ beta polymorphism and genetic susceptibility to Felty's syndrome

We used an oligonucleotide probe specific for a polymorphic sequence in the HLA-DQ beta gene to investigate the role of DQ polymorphism in genetic susceptibility to Felty's syndrome (FS) and rheumatoid arthritis (RA). The sequence of this gene was identified from a complementary DNA library derived from an RA patient's B lymphoblastoid cell line. With this probe, we studied the prevalence of the specific DQ beta allele in DR4 positive FS patients, RA patients, and normal control subjects. Significantly more FS patients (17 of 25) showed hybridization with this oligonucleotide probe, compared with the number of DR4 positive non-FS RA patients (7 of 23) and normal controls (7 of 21). The findings indicate that genes linked to the DQ region are important in determining susceptibility to FS.