HLA haplotype sharing by siblings with rheumatoid arthritis: evidence for genetic heterogeneity.

HLA haplotype sharing was studied in 35 sibships in which there were two or more members with rheumatoid arthritis (RA). Haplotype sharing RA siblings was random in 15 sibships which included members with clinical or immunological features of autoimmune thyroid disease. In the remaining 20 'non-thyroid' sibships the frequencies of RA siblings sharing 0, 1, or 2 haplotypes were 0.04, 0.48, and 0.48 respectively (p = 0.006). 67% of RA probands in the 'thyroid' families and 90% in the other families were HLA-DR4 positive. It is suggested that there is genetic heterogeneity in the pathogenesis of RA with at least two independent genes within the major histocompatibility complex (MHC) predisposing to RA. One gene is in linkage disequilibrium with HLA-DR4, while results of comparison of DR antigen frequencies in DR4 negative RA and control groups suggest that the other is in linkage disequilibrium with HLA-DR1 and 3. In the thyroid disease families both genes are frequently present and as either may predispose to arthritis, HLA haplotype sharing is random. The frequencies of HLA haplotype sharing in the 'non-thyroid' families suggest that there is a dominant susceptibility gene in linkage disequilibrium with HLA-DR4, whose frequency is 5% and penetrance about 20%.     

Effect of disease severity on rheumatoid arthritis concordance in same sexed siblings.

To assess the factors in a proband with rheumatoid arthritis (RA) that might predict the occurrence of the disease in siblings, 240 same sexed sibships (190 female, 50 male) in which the proband had classical or definite RA were clinically and immunologically documented. Sibship concordance rates were consistently higher for features of severe disease in the proband, reaching statistical significance for a clinical score of disease severity (the SS index). This trend for increasing disease severity to be associated with increasing sibship concordance rates could not be accounted for by age or disease duration of the proband. These results suggest that siblings of probands with severe RA are at greater risk of developing RA than those of probands with mild disease.     

Contribution of inherited factors to rheumatoid arthritis.

A total of 231 sibships of the same sex (186 female, 45 male), in which the proband had classical or definite rheumatoid arthritis (RA) have been selected from rheumatology clinics. Each sibship member was questioned about symptomatic joints, which were then examined. Hospital records, radiographs, and rheumatoid factor measurements allowed each sibling to be classified as having classical, definite, probable, or no RA. Each sibling was typed for HLA-A and B and was classified as sharing two, one, or zero HLA haplotypes with the proband. Concordance rates for classical and definite RA were three times greater in sibships of women than of men (9.3 v 3.0%). Concordance rates in HLA identical sibships were twice those in hemi- and non-identical sibships (15.5, 7.1, and 5.2%, respectively). Probable RA was more common in male and HLA hemi- and non-identical sibships. These results suggest that female sex and the two inherited HLA haplotypes are important for the presence and expression of RA. Although environmental factors may be shared more in twins than siblings, a concordance rate of 20.5% in seropositive HLA identical sibships of the same sex compared with 30% in monozygotic twins suggests that sex and HLA type account for about two thirds of the inherited risk of RA.     

RHEUMATOID ARTHRITIS IN THYROID DISEASE POSITIVE AND NEGATIVE SAME-SEXED SIBSHIPS

A total of 249 rheumatoid arthritis (RA) same-sexed sibshipswere clinically documented, HLA-typed and had autoantibody screensperformed. Sibships with a history of thyroid disease (TD) orsignificant thyroid antibodies were categorized as ‘thyroid’sibships and the rest ‘non-thyroid’. TD was morecommon in the female RA sibships than controls, particularlyin the RA probands. The presence of thyroid microsomal antibody,but not thyroglobulin antibody, was significantly higher inall members of the female sibships, and in the probands andnon-RA siblings of the male sibships. Comparing the thyroidand non-thyroid sibships, there was no significant differencein the distribution of HLA haplotypes in RA-RA sibling pairs,and HLA-DR status, clinical or immunological characteristicsof the probands. These data do not support the concept thatpredisposition to RA in thyroid sibships might be non-DR4 ornon-HLA linked. KEY WORDS: Thyroid autoantibodies, Prevalence, HLA haplotypes, HLA-DR, Immunogenetics     

What factors distinguish probands from multicase rheumatoid arthritis same sex sibships from sporadic disease?

Thirty-two of 243 same sex sibships in which the proband had rheumatoid arthritis (RA) had at least one same sex sibling with RA ("familial" RA) and 211 did not ("sporadic" RA). The most important factors accounting for familial RA were the sibship size, and the proportion of siblings sharing both HLA haplotypes with the proband. Demographic and clinical details, autoantibodies and HLA-DR status were similar between the 2 groups, with the exceptions of regular use of artificial teardrops, and involvement of distal interphalangeal joints, which were both more prevalent in familial RA. The extrapolation of results from familial to sporadic RA appears to be justified.     

Extreme genetic risk for type 1A diabetes

Type 1A diabetes (T1D) is an autoimmune disorder the risk of which is increased by specific HLA DR/DQ alleles [e.g., DRB1*03-DQB1*0201 (DR3) or DRB1*04-DQB1*0302 (DR4)]. The genotype associated with the highest risk for T1D is the DR3/4-DQ8 (DQ8 is DQA1*0301, DQB1*0302) heterozygous genotype. We determined HLA-DR and -DQ genotypes at birth and analyzed DR3/4-DQ8 siblings of patients with T1D for identical-by-descent HLA haplotype sharing (the number of haplotypes inherited in common between siblings). The children were clinically followed with prospective measurement of anti-islet autoimmunity and for progression to T1D. Risk for islet autoimmunity dramatically increased in DR3/4-DQ8 siblings who shared both HLA haplotypes with their diabetic proband sibling (63% by age 7, and 85% by age 15) compared with siblings who did not share both HLA haplotypes with their diabetic proband sibling (20% by age 15, P < 0.01). 55% sharing both HLA haplotypes developed diabetes by age 12 versus 5% sharing zero or one haplotype (P = 0.03). Despite sharing both HLA haplotypes with their proband, siblings without the HLA DR3/4-DQ8 genotype had only a 25% risk for T1D by age 12. The risk for T1D in the DR3/4-DQ8 siblings sharing both HLA haplotypes with their proband is remarkable for a complex genetic disorder and provides evidence that T1D is inherited with HLA-DR/DQ alleles and additional MHC-linked genes both determining major risk. A subset of siblings at extremely high risk for T1D can now be identified at birth for trials to prevent islet autoimmunity.     

HLA: linkage with rheumatoid arthritis or seropositivity

HLA haplotype sharing was compared in sibships from multicase families with rheumatoid arthritis (RA), subdivided by rheumatoid factor status, to investigate the claim that HLA is linked more to RA severity than susceptibility. Considerable deviation from expected (Mendelian) inheritance towards greater sharing of inherited parental haplotypes was observed in the sibships as a whole and when subdivided according to the serological status of the sibship's members. Further, there was no evidence that linkage was stronger in the seropositive concordant than in the other sibships. Linkage was also demonstrated between HLA and seropositivity even in sibships where not all members expressed clinical RA. These results, therefore, do not support the existence of genetic heterogeneity between seropositive and seronegative RA, a possibility previously suggested from population studies of antigen associations.     

HLA-linked hemochromatosis alleles in sporadic porphyria cutanea tarda

We tested the hypothesis that the hepatic siderosis that characterizes sporadic porphyria cutanea tarda is due to the presence of HLA-linked hemochromatosis alleles. We studied 21 probands with sporadic porphyria cutanea tarda and 135 of their relatives by determining HLA haplotypes and measuring transferrin saturation and serum ferritin concentration. Liver biopsies were performed in all probands and in relatives when appropriate. Seventeen pedigrees were available and were studied by both likelihood analysis and by a gene counting method. We estimated that 10 of the 17 probands with available living relatives possessed at least one hemochromatosis allele. Thirteen of the 21 probands (62%) possessed at least one HLA-A3 alloantigen. Eighteen of 69 relatives who shared an HLA haplotype with a proband (26%) had an elevation of transferrin saturation or serum ferritin concentration. Only one first-degree relative not sharing an HLA haplotype with a proband had an elevated transferrin saturation or serum ferritin concentration. These findings indicate that HLA-linked hemochromatosis alleles are far more common in patients with sporadic porphyria cutanea tarda than in individuals in the general population and may be responsible for the hepatic siderosis associated with most cases of sporadic porphyria cutanea tarda.     

Does genetic anticipation occur in familial rheumatoid arthritis?

OBJECTIVE--To determine if there is evidence for genetic anticipation in rheumatoid arthritis (RA) by analysing the possibility that parental disease status and age at proband conception influence the age of onset and disease severity of the proband. METHOD--RA outpatients were identified and data were also taken from Newcastle multicase RA pedigrees. Comparisons of age of onset and parental age at proband conception were made for pedigrees grouped according to the disease status of the parents. Correlation coefficients and linear regression models were calculated for the age of RA onset in the probands. Measures of disease severity were compared in RA mother-proband pairs. RESULTS--The results were similar in both the outpatient (n = 153) and multicase pedigree (n = 15) samples. Significant results were confined to pedigrees in which the mother had RA (20 of the outpatient probands and seven of the multicase group). Probands in these sibships had a younger age of RA onset than their affected mothers (38.3 years (95% confidence interval (CI) 33.8 to 42.8) versus 53.7 (47.3 to 60.0) (p = 0.002) in the outpatient sample; 32.4 years (25.3 to 39.6) versus 43.4 years (29.0 to 57.9) (p = 0.1) in the multicase pedigrees). In the maternal RA group, both the maternal and paternal age at proband conception showed significant negative correlations (r = -0.65, p = 0.002 and r = -0.60, p = 0.005, respectively in the outpatient sample) and linear regression coefficients with age of proband disease onset. In seven affected mother-proband pairs, the probands had a tendency to more severe disease, despite shorter disease duration and younger age. CONCLUSIONS--This preliminary analysis has suggested that within pedigrees in which the mother has RA, the features of genetic anticipation and observations consistent with premutation models may prevail.     

Familial aggregation of rheumatoid arthritis in The Netherlands: a cross-sectional hospital-based survey. European Consortium on Rheumatoid Arthritis families (ECRAF).

OBJECTIVES: To study the familial aggregation of rheumatoid arthritis (RA) in The Netherlands and to analyse the effect of proband characteristics on the concordance rates for RA. Secondary aims were to compare the characteristics of patients in an early RA inception cohort with those of regular patients and to select Dutch families for the genome-wide scan carried out by the European Consortium on RA families (ECRAF). METHODS: A cross-sectional, hospital-based survey aimed to identify affected sibpair (ASP) families among our whole RA population. Familial RA, or an ASP family, was defined by the presence of at least two siblings fulfilling the 1987 ACR criteria for RA. RESULTS: The estimated prevalence for familial RA was 9.8% and similar to that found in previous hospital series. The true-positive reporting rate for RA in sibs was 60%. Sibship size in ASP families (mean +/- S.D. = 7.8+/-3.3) was significantly larger than in the Dutch population. Probands with familial RA were more often rheumatoid factor positive and had a longer follow-up. Male gender and history of joint replacements were associated with higher concordance rates for RA. However, regression analysis showed that, correcting for sibship size, the concordance rate for RA was largely not explained by proband characteristics. Compared to regular RA patients, our inception cohort encompassed more male and/or rheumatoid factor-negative patients, but had similar performance in the study and rate of familial aggregation. CONCLUSIONS: The familial aggregation of RA in The Netherlands is not increased and occurs preferentially in large sibships. Among proband characteristics, sibship size is most clearly related to the recurrence of RA in particular families. Patients' recognition of RA manifestations in relatives is not optimal.     

Influence of familial factors on radiologic disease progression over two years in siblings with osteoarthritis at multiple sites: a prospective longitudinal cohort study

OBJECTIVE: The contribution of genetics to osteoarthritis (OA) progression is not known. To gain more insight into whether familial factors play a role in disease progression of OA, we analyzed familial aggregation of radiologic OA progression in a study of sibling pairs (the Genetics, Arthrosis, and Progression [GARP] study). METHODS: A total of 105 white probands and their 105 siblings with OA at multiple joint sites were included in a prospective cohort study. Radiologic progression of OA was defined as a 1-point score increase in total scores for severity of joint space narrowing (JSN) or osteophytes on standardized radiographs of the hands, knees, and hips obtained at baseline and after 2 years. Odds ratios were calculated for siblings and probands sharing radiologic disease progression. RESULTS: A total of 100 probands and 93 siblings were followed for 2 years (median age 60 years, 80% women). In 92 sibling pairs both the proband and sibling had complete radiographic followup. Radiologic progression of JSN and osteophytes was present in 47% and 42% of the probands and 34% and 37% of the siblings, respectively. The odds ratios (95% confidence intervals), adjusted for age, sex, and body mass index, of a sibling having radiologic progression if the proband had progression were 3.0 (1.2-7.8) for JSN progression and 1.5 (0.6-3.6) for osteophyte progression. A dose-response relationship was found between the amount of increase in JSN total scores among probands and the progression of JSN in siblings. CONCLUSION: Familial factors played a role in the radiologic progression of JSN over 2 years in patients with OA at multiple sites.     

HLA-linked control of predisposition to lepromatous leprosy

In order to investigate if genes conferring susceptibility to leprosy and/or predisposition to a particular leprosy type are linked to HLA, we performed HLA-A and HLA-B typing on members of 29 families containing at least two siblings affected with leprosy from a leprosy endemic area in Jiangsu Province, People's Republic of China. Moreover, we performed a lepromin test in nearly all of the members of eight families containing at least two siblings affected with lepromatous leprosy. For 26 families the data permitted analyses of the segregation of parental HLA-haplotypes observed among children in relation to leprosy status. Siblings affected with lepromatous (LL or BL) leprosy shared parental HLA-haplotypes significantly more often than expected (p less than 0.05), and a highly significant deficit (p less than 0.0005) of shared HLA-haplotypes was observed among affected siblings discordant for leprosy type. These data confirm the HLA-linked control of leprosy type and, in particular, recently obtained evidence for linkage of predisposition to lepromatous leprosy with HLA. Healthy siblings did not share a haplotype more often than expected, and those haplotypes which were shared among all leprosy patients of a sibship did not occur less frequently than expected among the healthy siblings of the same sibship. The latter data confirm the absence of linkage of genes conferring susceptibility or resistance to leprosy with HLA. An analysis of the lepromin test results observed among healthy siblings showed no evidence for cosegregation of the results with HLA.     

HLA in maturity-onset type of hyperglycemia in the young

HLA haplotypes in a kindred with a maturity-onset type of hyperglycemia in the young (MOHY) were studied. All diabetics had mild hyperglycemia of early onset, and the inheritance pattern suggested an autosomal dominant trait. Eight of 11 subjects with hyperglycemia shared haplotype A3, Bw15. When only this haplotype was considered, there appeared to be a significant association with hyperglycemia chi2 = 6.36). However, since both haplotypes in the proband could be associated with hyperglycemia (both proband's parents had hyperglycemia), the data for both haplotypes were combined, and analysis for an association between both haplotypes and hyperglycemia was not significant (chi2 = 2.53). Linkage between a diabetes gene causing MOHY and the HLA, evaluated by lod score analysis, was suggested, but the values were not significant.     

Common variable immunodeficiency and IgG subclass deficiency in central Alabama hemochromatosis probands homozygous for HFE C282Y

Eight hemochromatosis probands with HFE C282Y homozygosity had frequent, severe, or unusual infections and common variable immunodeficiency (CVID) or immunoglobulin (Ig) G subclass deficiency (IgGSD). Thus, we performed serum Ig isotyping and other characterization of 43 additional unselected probands, 5 human leukocyte antigen (HLA)-identical siblings, and 240 consecutive CVID or IgGSD index patients. C282Y allele frequencies were estimated in 58 CVID or IgGSD index patients without hemochromatosis phenotypes and in 341 controls. HLA-A and -B haplotypes and frequencies were determined in all 51 probands, 186 CVID or IgGSD index patients without hemochromatosis phenotypes, and 751 controls. Thirteen unselected probands (30%) had CVID or IgGSD. Among all 21 hemochromatosis probands with CVID (n = 4) or IgGSD (n = 17), Ig subclass deficiency patterns were IgG(1) (n = 5), IgG(1) and IgG(3) (n = 6), IgG(3) (n = 9), and IgG(1), IgG(3), and IgG(4) (n = 1). IgG(2) or IgA deficiency was not detected; one proband had IgM deficiency. Mean values of total IgG, IgG(1), and IgG(3) were significantly lower in probands with CVID or IgGSD. Mean values of age, transferrin saturation, and ferritin at diagnosis and phlebotomy units required to induce iron depletion were similar in probands with or without CVID or IgGSD; phlebotomy had no apparent effect on IgG levels. C282Y frequencies were similar in CVID or IgGSD index cases without hemochromatosis phenotypes and in controls. There was concordance of Ig and hemochromatosis phenotypes in probands and respective HLA-identical siblings. Eight of 240 CVID or IgGSD index patients had hemochromatosis phenotypes and C282Y homozygosity (3 vs 0.7% and 0.2% controls; P < 0.0001, respectively). The frequency of A*03-B*07 was greater in CVID and IgGSD index cases without hemochromatosis phenotypes than in controls (0.0968 vs 0.0546, respectively; P = 0.0032). HLA-A*03-B*07 was the predominant haplotype in probands grouped by presence or absence of CVID or IgGSD. Some probands in each group were A*03-B*07 homozygotes; group A*03-B*07 frequencies were similar. We conclude that serum IgG abnormalities characteristic of CVID or IgGSD are common in hemochromatosis probands, and that the prevalence of hemochromatosis is increased in CVID and IgGSD index cases. These observations could be explained by the increased frequencies of HLA-A*03-B*07 in C282Y homozygotes and in CVID and IgGSD, and by the common occurrence of putative CVID or IgGSD allele(s) on haplotypes bearing C282Y.     

A poly(ADP-ribose) polymerase haplotype spanning the promoter region confers susceptibility to rheumatoid arthritis

OBJECTIVE: To investigate the association of the poly(ADP-ribose) polymerase 1 (PARP-1) gene promoter polymorphism with rheumatoid arthritis (RA) predisposition. METHODS: An association study with 213 Spanish RA patients and 242 healthy subjects was carried out to investigate the association of all known PARP-1 gene promoter polymorphisms, i.e., a CA microsatellite repeat, a poly(A)(n), and 3 single point mutations (C410T, C1362T, and G1672A), with disease susceptibility. Additionally, we analyzed the distribution of PARP-1 polymorphisms in 58 Spanish families with 1 or more affected members. RESULTS: Upon complete genotyping of the panel of 455 samples, strong linkage disequilibrium was observed among the 5 PARP-1 polymorphisms. Only 2 PARP-1 haplotypes were detected: haplotype A (410T-[A](10)-[CA](10-12)-1362C, which includes short PARP-1 CA alleles) and haplotype B (410C-[A](11)-[CA](13-20)-1362T, always paired with long PARP-1 CA variants). Regarding the G1672A variation, although linkage disequilibrium was detected, it did not seem to be part of the conserved haplotypes described. Haplotype B was statistically overrepresented in the RA patient group compared with the healthy subjects (odds ratio 1.42, 95% confidence interval 1.06-1.91, P = 0.019). In addition, a significant dose effect of PARP-1 haplotype carriage on disease predisposition was observed. Of note, within haplotype B, the PARP-1 CA 97-bp allele was found to be the RA-predisposing marker (odds ratio 2.17, 95% confidence interval 1.27-3.72, P = 0.003, corrected P < 0.05). CONCLUSION: Our results demonstrate the existence of 2 unique PARP-1 haplotypes in the Spanish population and provide the first evidence that PARP-1 haplotypes play a role in susceptibility to RA.     

Glucose tolerance in siblings of Type 1 diabetic patients relationship to HLA status

Summary In this report, we present an analysis of glucose and insulin responses during oral glucose tolerance tests in 369 siblings of Type 1 diabetic patients. All have been HLA typed at the A, B and C loci. Though most had normal glucose tolerance by National Diabetes Data Group criteria (92% of the males and 95% of the females), siblings who shared both HLA haplotypes with the diabetic patient in the family had higher mean 3-hour glucose areas than those who shared one or neither HLA haplotype (p < 0.01). This difference was more marked in males and older siblings. Insulin concentrations did not differ significantly between the two groups except that, for those aged <16 years, the group sharing both haplotypes had lower fasting insulin concentrations (p = 0.05); for 16–29 year olds, the corresponding group had marginally higher 3-hour insulin areas than the remainder of siblings (p = 0.17). Little association with specific haplotypes (A₁B₈ or A₂B₁₅) was seen. Multivariate analyses, adjusting for age and obesity, eliminated the 3-h glucose difference in females by HLA sharing status (p = 0.37) although in males it remained significant (p < 0.001). Failure to account for age, sex and obesity may explain some of the conflicts in the reported literature. The glucose tolerance differences seen by HLA haplotype sharing status did not correlate with the presence of anti-islet cell antibodies. These results are consistent with the hypothesis that the HLA identical siblings, particularly males, have different (i. e. worse) glucose tolerance than their haplo-identical and non-HLA identical siblings.     

HLA haplotypes and susceptibility to rheumatoid arthritis. More than class II genes

Our aim was to examine, using microsatellite (ms) markers, the contribution of the telomeric part of the HLA region to rheumatoid arthritis (RA) predisposition in the Spanish population. We have looked at the distribution of DQB1, DRBI and five ms loci (D6S1014, D6S273, D6STNFa, MIB and C1-2-5) within the HLA region in 147 Spanish RA patients and 202 control subjects. A total of 19 conserved ms configurations were observed, twelve of them in linkage disequilibrium with particular DQB1-DRB1 haplotypes. Interestingly, haplotype c1 (DQB1*0201-DRB1*0301-D6S1014*143-D6S273*139-D6STNFa*99-MIB*350-C1-2-5*196) was significantly associated with RA predisposition. As part of this haplotype, the MIB*350 allele was found to be a risk factor independently of the RA-predisposing haplotypes. The present results along with data from others prove the existence of a second predisposing locus located inside the MHC region, and suggest that might be located within the TNFa-HLA-B region.     

HLA haplotypes in a family with multiple cases of rheumatoid arthritis

Population studies have identified the histocompatibility antigen HLA-DR4 to be a genetic marker of significantly increased risk for the development of rheumatoid arthritis (RA). Family studies are now beginning to elucidate the role of this and other genetic factors in the pathogenesis of RA. We have studied a large family in which the mother and 3 of the 6 children have seropositive RA. One maternal and 1 paternal HLA haplotype contain HLA-DR4. The mother and the 2 children with the maternal DR4 containing haplotype have RA. One sibling inherited neither of the DR4 haplotypes, yet developed RA at age 20. The inheritance of RA in this family illustrates the complexity of the genetic predisposition to this immunologically mediated disorder.     

Family study of fibromyalgia

OBJECTIVE: To assess for familial aggregation of fibromyalgia (FM) and measures of tenderness and pain, and for familial coaggregation of FM and major mood disorder (major depressive disorder or bipolar disorder). METHODS: Probands meeting the American College of Rheumatology criteria for FM and control probands with rheumatoid arthritis (RA) and no lifetime diagnosis of FM were recruited from consecutive referrals to 2 community-based rheumatology practices. Probands were ages 40-55 years and had at least 1 first-degree relative age 18 years or older who was available for interview and examination. All probands and interviewed relatives underwent a dolorimeter tender point examination and a structured clinical interview. Interviewed relatives were asked about first-degree relatives who were not available for interview, using a structured family interview. Logistic and linear regression models, adjusting for the correlation of observation within families, were applied to study the aggregation and coaggregation effects. RESULTS: Information was collected for 533 relatives of 78 probands with FM and 272 relatives of 40 probands with RA. FM aggregated strongly in families: the odds ratio (OR) measuring the odds of FM in a relative of a proband with FM versus the odds of FM in a relative of a proband with RA was 8.5 (95% confidence interval [95% CI] 2.8-26, P = 0.0002). The number of tender points was significantly higher, and the total myalgic score was significantly lower in the relatives of probands with FM compared with the relatives of probands with RA. FM coaggregated significantly with major mood disorder: the OR measuring the odds of major mood disorder in a relative of a proband with FM versus the odds of major mood disorder in a relative of a proband with RA was 1.8 (95% CI 1.1-2.9, P = 0.013). CONCLUSION: FM and reduced pressure pain thresholds aggregate in families, and FM coaggregates with major mood disorder in families. These findings have important clinical and theoretical implications, including the possibility that genetic factors are involved in the etiology of FM and in pain sensitivity. In addition, mood disorders and FM may share some of these inherited factors.