Analysis of SAA1 gene polymorphisms in the Greek population: rheumatoid arthritis and FMF patients relative to normal controls. Homogeneous distribution and low incidence of AA amyloidosis

Objective. To address whether or not the rarity of amyloidosis in Greek patients with rheumatoid arthritis (RA) is related to specific alleles of single nucleotide polymorphisms (SNPs) in the 5′-flanking region and the exon 3 of the SSA1 gene.

Methods. The genotypes of the ?13T/C SNP in the 5′-flanking region of the SAA1 gene and the two SNPs within exon 3 of SAA1 (2995C/T and 3010C/T polymorphisms) were determined in 88 Greek patients with RA, 14 patients with familial Mediterranean fever (FMF) and 110 healthy controls. Linkage disequilibrium and haplotype frequencies involving ?13T/C, 2995C/T and 3010C/T in these populations were tested and estimated, respectively.

Results. The genotypic distribution and allelic frequencies were similar in all groups tested. SNPs 2995 and 3010 were in linkage disequilibrium for all study populations (p < 0.05), whereas SNP ?13 was not in linkage disequilibrium with either 2995 or 3010 (p ≥ 0.05). Two major haplotypes presented in all patients with RA and FMF and controls: ?13C; 2995T; 3010C (?13C; α) and ?13C; 2995C; 3010T (?13C; β). The ?13T allele was linked with the γ haplotype in Greek patients with RA and controls. The frequency of the ?13T allele was found to be very rare in all groups tested.

Conclusions. In conclusion, the rarity of the putative amyloidogenic ?13T allele in Greek populations may be related to low prevalence of AA amyloidosis development in Greek RA patients.     

SAA1 gene polymorphisms and the risk of AA amyloidosis in Japanese patients with rheumatoid arthritis

To investigate the precise modality of association between SAA1 gene polymorphisms and the development of AA amyloidosis in patients with rheumatoid arthritis (RA), Japanese patients with RA (n = 153), among whom 29 were histologically diagnosed as having amyloidosis, were genotyped for three single nucleotide polymorphisms (SNPs), C-13T, C2995T, and C3010T, in the SAA gene. Pairwise linkage disequilibrium coefficients between each pair of SNPs were calculated and estimated haplotype frequencies were compared between patients with and without amyloidosis. Possible associations between these SNPs and amyloidosis were analyzed by a case–control study and by the Kaplan–Meier method, in which the endpoint was defined as the time of diagnosis of AA amyloidosis. The -13T and 2995C alleles, which were in a tight linkage disequilibrium, were more frequent in the patients with amyloidosis, and the groups with the -13TT and 2995CC genotype had worse survival curves than patients without these genotypes, whereas C3010T was not associated with amyloidosis. Moreover, the haplotype containing −13C and 2995T was found to be protective. Both C-13T and C2995T were associated with the development of amyloidosis. Examining both polymorphisms may be more useful than examining only one of them for estimating the risk of the development of amyloidosis.     

SAA1 gene polymorphisms and the risk of AA amyloidosis in Japanese patients with rheumatoid arthritis

Abstract

To investigate the precise modality of association between SAA1 gene polymorphisms and the development of AA amyloidosis in patients with rheumatoid arthritis (RA), Japanese patients with RA (n = 153), among whom 29 were histologically diagnosed as having amyloidosis, were genotyped for three single nucleotide polymorphisms (SNPs), C-13T, C2995T, and C3010T, in the SAA gene. Pairwise linkage disequilibrium coefficients between each pair of SNPs were calculated and estimated haplotype frequencies were compared between patients with and without amyloidosis. Possible associations between these SNPs and amyloidosis were analyzed by a case–control study and by the Kaplan–Meier method, in which the endpoint was defined as the time of diagnosis of AA amyloidosis. The -13T and 2995C alleles, which were in a tight linkage disequilibrium, were more frequent in the patients with amyloidosis, and the groups with the -13TT and 2995CC genotype had worse survival curves than patients without these genotypes, whereas C3010T was not associated with amyloidosis. Moreover, the haplotype containing ?13C and 2995T was found to be protective. Both C-13T and C2995T were associated with the development of amyloidosis. Examining both polymorphisms may be more useful than examining only one of them for estimating the risk of the development of amyloidosis.     

Efficacy of etanercept in patients with AA amyloidosis secondary to rheumatoid arthritis

OBJECTIVE: The efficacy of biological therapies in rheumatoid arthritis (RA) is well known, but their hypothetical benefit in amyloid A (AA) amyloidosis secondary to RA still remains to be considered. We evaluated the efficacy and safety of etanercept in serum amyloid A (SAA) 1.3 allele Japanese patients with AA amyloidosis secondary to RA. METHODS: Seven RA patients with histologically confirmed AA amyloidosis and renal involvement who were treated with etanercept were enrolled. They all had the SAA1.3 allele, which has been shown to be a risk factor not only for the association of AA amyloidosis but also for a poor prognosis in Japanese RA patients. Efficacy was assessed as a sustained decrease in RA inflammation and an amelioration of renal function. RESULTS: RA inflammation and AA amyloidosis were improved and stabilized after 43.4 +/- 16.5 weeks. At week 20 the number of tender (p = 0.017) and swollen (p = 0.017) joints, and levels of serum C-reactive protein (p = 0.018) and albumin (p = 0.045) had improved. The values for SAA, serum creatinine, calculated creatinine clearance, and proteinuria also ameliorated. No severe adverse events were observed. One patient eventually had to go on hemodialysis but her tolerance of etanercept remained stable. CONCLUSION: Etanercept can be used safely and effectively in AA amyloidosis secondary to RA with renal involvement, and is of clinical benefit in the short-term, even in patients on hemodialysis. It appears that SAA1.3 allele may be used as a clinical parameter for the introduction of etanercept in Japanese RA with AA amyloidosis.     

A novel single-nucleotide polymorphism at the 5'-flanking region of SAA1 associated with risk of type AA amyloidosis secondary to rheumatoid arthritis.

OBJECTIVE: To address whether the gamma haplotype at exon 3 of the SAA1 gene is directly associated with type AA amyloidosis or is merely in linkage with an unknown polymorphism that is primarily associated with disease risk, we examined the SAA1 gene for new polymorphisms. METHODS: We analyzed DNA samples from 44 rheumatoid arthritis (RA) patients with AA amyloidosis (amyloid group), 55 RA patients without AA amyloidosis (RA group), and 58 non-RA healthy subjects (non-RA group). We also examined DNA samples from 50 Caucasians to compare linkage disequilibrium relationships involving SAA1 region polymorphisms between Japanese and Caucasoid populations. RESULTS: We observed 3 novel single-nucleotide polymorphisms (SNPs) in the 5'-flanking region of SAA1: -61C/G, -13T/C, and -2G/A. Comparison of allele frequencies and ratios of individuals with particular alleles between the study groups revealed statistically significant differences between the amyloid and RA groups and between the amyloid and non-RA groups. Statistical analysis revealed that the -13T/C SNP was strongly associated with AA amyloidosis. In addition, we found tight linkage between the -13T allele and the alpha haplotype, rather than the beta haplotype, at exon 3 in the Caucasoid population, while -13T was closely linked to the gamma and beta haplotypes, rather than the alpha haplotype, in the Japanese population. Since the linkage disequilibrium relationship was reversed between the Japanese and Caucasoid populations, different exon 3 haplotypes of SAA1 are found to be associated with the risk of AA amyloidosis in different ethnic groups. CONCLUSION: Our data suggest that the SAA1 -13T allele, rather than SAA1 exon 3 haplotypes, is primarily associated with AA amyloidosis risk.     

Significance of SAA1.3 allele genotype in Japanese patients with amyloidosis secondary to rheumatoid arthritis

OBJECTIVE: To clarify the clinical significance of the SAA1.3 allele in the development and outcome of AA amyloidosis in Japanese patients with rheumatoid arthritis (RA). METHODS: One hundred and twenty RA patients (60 alive and 60 dead) fulfilling the 1987 ACR criteria and 62 RA patients with biopsy-confirmed amyloid A (AA) amyloidosis (36 alive and 26 dead) were enrolled. The SAA1 genotypes were determined by PCR-based restriction fragment length polymorphism. To predict the clinical outcome of AA amyloidosis, we investigated characteristics and survival, focusing on the SAA1.3 allele retrospectively. RESULTS: The SAA1.3 allele genotype was not only a risk factor for the association of AA amyloidosis but also a poor prognostic factor for the development of AA amyloidosis (P=0.015). Both the association of AA amyloidosis arising early in the RA disease course and symptomatic variety and severity were found in amyloidotic patients with the SAA1.3 allele. The presenting factors adversely influenced were age (P=0.001), lowered serum albumin (P=0.001) and creatinine concentration (P=2.14 x 10(-5)). Renal involvement was associated with poor survival in patients with AA amyloidosis (P=0.011) and the presence of cardiac involvement was likely to be a risk factor for survival (P=0.062). The rate of the causes of death in respect to the category of infection, gastrointestinal diseases, and renal failure was higher in patients with AA amyloidosis than in those without amyloidosis, gastrointestinal diseases and renal failure. Cyclophosphamide was found to be superior to methotrexate in the management of RA patients with AA amyloidosis. CONCLUSION: Our data support the fact that homozygosity for the SAA1.3 allele is a univariate predictor of survival in addition to a risk factor for the association of AA amyloidosis adversely influencing the outcome in Japanese RA patients. Renal involvement is a pivotal clinical manifestation in the development of AA amyloidosis, as is likely to be cardiac involvement in AA amyloidosis secondary to RA.     

Spontaneous pneumoperitoneum: an unusual complication of systemic reactive AA amyloidosis secondary to rheumatoid arthritis.

We report a 71-year-old man with reactive AA amyloidosis secondary to rheumatoid arthritis who developed spontaneous pneumoperitoneum with intestinal pseudo-obstruction as an initial symptom. Severe deposition of amyloid in the intestinal wall was considered to play an important role in the pathogenesis of this unusual symptom. The patient has been successfully treated with total parenteral alimentation and intermediate-dose prednisolone (30 mg/day). Although pneumoperitoneum usually suggests gastrointestinal perforation requiring emergency surgery, conservative therapy should be seriously considered in amyloidosis-related cases with no associated peritonitis, since multiple vital organs are probably involved by severe amyloid deposition, thus increasing the risks of surgery.     

Efficacy of cyclophosphamide combined with prednisolone in patients with AA amyloidosis secondary to rheumatoid arthritis

Secondary amyloid A (AA) amyloidosis is an uncommon yet important complication of rheumatoid arthritis (RA). It is one of the most relentless of the extra-articular features of RA, and suitable treatments have not yet been found. We studied the efficacy of cyclophosphamide (CYC) combined with prednisolone (PSL) in amyloidotic patients who had serum amyloid A (SAA) 1.3 genotype, which is a risk factor for secondary amyloidosis in Japanese RA patients. Fifteen RA patients who were SAA1.3 homo- and heterozygotes with biopsy-confirmed AA amyloidosis were treated with a combination of CYC and PSL. Laboratory variables of C-reactive protein (CRP), rheumatoid factor (RF), erythrocyte sedimentation rate (ESR), serum albumin (Alb), serum creatinine (Cre) and Lansburys index were carried out by statistical analysis of changes between before and during the medication. According to the Mann–Whitney rank test, CRP, RF, ESR, Alb and Cre levels improved significantly with the combination treatment (p<0.05). Also, paired t-tests showed significance in Lansburys index between before and during the medication (p=0.007). CYC combined with PSL ameliorated not only laboratory markers but also clinical rheumatoid activity in patients with amyloidosis secondary to RA, whose genotypes were SAA1.3 homo- and heterozygous. CRP, ESR, RF, Alb and Cre will be surrogate markers of therapeutic efficacy. The combination of CYC and PSL appears to be beneficial for Japanese RA patients who are SAA1.3 homo- and heterozygous carriers, associated with secondary AA amyloidosis.Abbreviations AA Amyloid A - CRP C-reactive protein - Ccr Creatinine clearance - CYC Cyclophosphamide - DMARD Disease-modifying antirheumatic drugs - ESR Erythrocyte sedimentation rate - NSAID Non-steroidal anti-inflammatory drugs - PCR Polymerase chain reaction - PSL Prednisolone - RA Rheumatoid arthritis - RF Rheumatoid factor - SAA Serum amyloid A     

Influence of Serum Amyloid A (SAA1) and SAA2 gene polymorphisms on renal amyloidosis, and on SAA/C-reactive protein values in patients with familial mediterranean fever in the Turkish population

OBJECTIVE: To evaluate the effect of serum amyloid A (SAA) 1 and SAA2 gene polymorphisms on SAA levels and renal amyloidosis in Turkish patients with familial Mediterranean fever (FMF). METHODS: SAA1 and SAA2 gene polymorphisms and SAA levels were determined in 74 patients with FMF (39 female, 35 male; median age 11.5 yrs, range 1.0-23.0). All patients were on colchicine therapy. SAA1 and SAA2 gene polymorphisms were analyzed using polymerase chain reaction restriction fragment length polymorphism (PCR-RFLP). SAA and C-reactive protein (CRP) values were measured and SAA/CRP values were calculated. RESULTS: The median SAA level was 75 ng/ml (range 10.2-1500). SAA1 gene polymorphisms were: a/a genotype in 23 patients (31.1%), a/beta genotype in 30 patients (40.5%), a/g genotype in one patient (1.4 %), beta/beta genotype in 14 patients (18.9%), beta/g genotype in 5 patients (6.8 %), and g/g genotype in one patient (1.4%). Of the 23 patients who had a/a genotype for the SAA1 polymorphism, 7 patients had developed renal amyloidosis (30.4%) compared to only one patient without this genotype (1/51; 2.0%); p < 0.001. SAA2 had no effect on renal amyloidosis. SAA1 and SAA2 genotypes had no significant effect on SAA levels. SAA/CRP values were significantly lower in patients with the SAA1a/a genotype, compared to other SAA1 genotypes: 0.16 (0.025-1.96) versus 0.23 (0.012-28.20), p < 0.05. CONCLUSION: SAA1a/a genotype is one genetic factor that confers a significant risk for amyloidosis in the Turkish FMF population. Neither the SAA1 nor SAA2 genotypes had a significant effect on SAA level.     

Long-term follow-up of systemic reactive AA amyloidosis secondary to rheumatoid arthritis: successful treatment with intermediate-dose corticosteroid

Reactive AA amyloidosis frequently develops in patients with a long history of rheumatoid arthritis (RA), usually resulting in an unfavorable outcome due to dysfunction of the vital organs. We report a 56-year-old woman with this form of amyloidosis secondary to RA who has been successfully treated with intermediate-dose prednisolone for two and a half years since diagnosis. Because prednisolone is superior to other drugs used for amyloidosis with respect to possible harmful effects on vital organs, we can safely try this drug as an alternative therapy to improve the prognosis even in patients with severe organ dysfunction.     

Bone mineral density in patients with hand osteoarthritis compared to population controls and patients with rheumatoid arthritis

Objectives

Several studies have revealed increased bone mineral density (BMD) in patients with knee or hip osteoarthritis, but few studies have addressed this issue in hand osteoarthritis (HOA). The aims of this study were to compare BMD levels and frequency of osteoporosis between female patients with HOA, rheumatoid arthritis (RA) and controls aged 50–70 years, and to explore possible relationships between BMD and disease characteristics in patients with HOA.

Methods

190 HOA and 194 RA patients were recruited from the respective disease registers in Oslo, and 122 controls were selected from the population register of Oslo. All participants underwent BMD measurements of femoral neck, total hip and lumbar spine (dual‐energy x ray absorptiometry), interview, clinical joint examination and completed self‐reported questionnaires.

Results

Age‐, weight‐ and height‐adjusted BMD values were significantly higher in HOA versus RA and controls, the latter only significant for femoral neck and lumbar spine. The frequency of osteoporosis was not significantly different between HOA and controls, but significantly lower in HOA versus RA. Adjusted BMD values did not differ between HOA patients with and without knee OA, and significant associations between BMD levels and symptom duration or disease measures were not observed.

Conclusion

HOA patients have a higher BMD than population‐based controls, and this seems not to be limited to patients with involvement of larger joints. The lack of correlation between BMD and disease duration or severity does not support the hypothesis that higher BMD is a consequence of the disease itself.Osteoporosis is recognised as a frequent complication to rheumatoid arthritis (RA).¹ Osteoarthritis (OA) is the most frequent rheumatic joint disease, and contrary to the situation in RA, several studies have revealed increased bone mineral density (BMD) in patients with knee or hip OA, even if the results have not been consistent in all studies.^{2,3,4,5,6,7,8,9,10} The hand is a frequent site of peripheral joint involvement in OA. However, a limited number of studies have addressed the issue of osteoporosis in hand osteoarthritis (HOA), and the results from these few studies have been inconsistent regarding levels of BMD compared with controls.^{8,9,10,11,12,13,14,15}OA has generally been considered as a cartilage disease characterised by slow progressive degeneration of articular cartilage due to “wear and tear” mechanisms. However, there is increasing evidence that abnormalities in the subchondral bone and systemic factors may contribute to the pathophysiological process. Studies of subchondral bone have revealed alterations in microstructure including increased BMD. This local increase in BMD in OA joints may be a consequence of reduced shock absorption in joints with degenerated cartilage,⁵ or on the contrary, thickening and stiffening of the subchondral bone with increased BMD may lead to development of OA.¹⁶ However, elevated BMD levels at sites remote from the arthritic process cannot be explained by local biomechanical factors, and the question of whether primary OA rather is a systemic bone disease has been raised.¹⁷ Systemic changes in subchondral bone could be explained by genetic factors, hormonal influences, vitamin D concentrations, growth factors or activity of bone‐forming cells.^{15,18,19,20,21} Better knowledge about the relationship between BMD and HOA may contribute to the understanding of the pathogenesis of OA.Disease registers of patients with RA²² and HOA²³ have been established in the city of Oslo. We have previously compared BMD levels in a cohort of RA patients from the Oslo RA Register (ORAR) and healthy controls.²⁴ The current study was designed to compare levels of BMD and the frequency of osteoporosis between patients with HOA, RA and controls. A second aim was to explore possible relationships between BMD levels and disease characteristics in patients with HOA.     

Lack of association between IL-6 gene polymorphisms and rheumatoid arthritis in Turkish population

Inflammatory cytokines play an important role in the pathogenesis of rheumatoid arthritis (RA). One of candidate genes is interleukin-6 (IL-6), and single-nucleotide polymorphisms in the promoter region of IL-6 were found to be associated with RA. The aim of this study was to determine the association between IL-6 promoter polymorphisms (-174, -572, -597) and RA in Turkish population. A total of 425 subjects were recruited into the study (247 healthy controls and 178 RA). The promoter region of IL-6 gene was amplified by PCR using DNAs from patients and the controls, and their PCR products were digested by suitable enzymes. No significant association was found between RA and -174 genotype distribution (P = 0.535) and allele frequency (P = 0.230). There was also no relationship between -572 (P = 0.150) and -597 (P = 0.912) gene polymorphism and RA. Our results suggested that IL-6 gene promoter polymorphisms have no association with RA in Turkish population.     

Actigraphic measurements of sleep in rheumatoid arthritis: comparison of patients with low back pain and healthy controls.

Actigraphic recordings during sleep were carried out in patients with rheumatoid arthritis (RA), in patients with chronic low back pain, and in healthy controls for 4 consecutive nights. All derived measures of sleep quality showed that the sleep of patients with RA was significantly poorer than controls, while patients with chronic low back pain had sleep quality not significantly different from either group. Polysomnographically defined periodic movements in sleep were significantly related to sleep efficiency in patients with RA. Clinical status in these patients was significantly related to several actigraphic sleep measures.     

The impact of rheumatoid arthritis and osteoarthritis: the activities of patients with rheumatoid arthritis and osteoarthritis compared to controls

We measured the impact of rheumatoid arthritis (RA) and osteoarthritis (OA) by comparing the activities of patients with these illnesses to controls matched for age, sex, and community of residence. Our results indicate that patients with RA experience more losses than controls in every domain of human activity and that patients with OA experience more losses in the performance of household chores, shopping and errands, and leisure activities. The methods described here provide a simple, reliable way to assess the impacts of illness in the same terms for all dimensions of human activity.     

Tocilizumab-induced hyperbilirubinemia in Japanese patients with rheumatoid arthritis: its association with UDP glucuronosyltransferase 1A1 gene polymorphisms

This study was performed to explore the possibility of an association between polymorphisms within the uridine diphosphate glucuronosyltransferase 1A1 gene (UGT1A1) and hyperbilirubinemia arising during tocilizumab therapy. We examined the distributions of 3 variant alleles, UGT1A1*6, *28, and *27, in 46 Japanese patients with rheumatoid arthritis (RA) who had received tocilizumab therapy for at least 24?weeks, grouped the patients according to their carriage status of these UGT1A1 variants, and determined the frequency of hyperbilirubinemia in each of the groups. Of the 46 patients treated with tocilizumab, 34 maintained normal bilirubin levels after 24?weeks, whereas the remaining 12 developed mild or moderate hyperbilirubinemia. Patients carrying 2 copies of UGT1A1*28 (*28/*28) were more likely to develop hyperbilirubinemia than those without UGT1A1*28. In addition, patients carrying 2 copies of variant alleles, either as homozygotes (UGT1A1*6/*6 or *28/*28) or as compound heterozygotes (UGT1A1*6/*28), were at higher risk of hyperbilirubinemia as compared with those without either UGT1A1*6 or UGT1A1*28 (odds ratio [OR] 28.33; 95% confidence interval [CI] 2.39-336.00; p?=?0.005). Multivariate logistic regression analysis confirmed the strong association of tocilizumab-induced hyperbilirubinemia with the presence of 2 copies of variant alleles (OR 25.51; 95% CI 2.35-276.53; p?=?0.008), yielding an area under the receiver operating characteristics curve of 0.78 (95% CI 0.60-0.95, p?=?0.005). Tocilizumab can induce hyperbilirubinemia in RA patients, especially those carrying UGT1A1*6/*6, *6/*28, and *28/*28 genotypes. Considering this genetic association, it may be unnecessary to withdraw this drug from RA patients in the absence of other signs of hepatic injury. Given that tocilizumab has the potential to inhibit UGT1A1-mediated glucuronidation, however, it may inhibit not only bilirubin metabolism but also UGT1A1-dependent detoxification of drugs, thereby increasing the risk of unwanted adverse events during RA therapy.     

Tocilizumab-induced hyperbilirubinemia in Japanese patients with rheumatoid arthritis: its association with UDP glucuronosyltransferase 1A1 gene polymorphisms

Abstract

This study was performed to explore the possibility of an association between polymorphisms within the uridine diphosphate glucuronosyltransferase 1A1 gene (UGT1A1) and hyperbilirubinemia arising during tocilizumab therapy. We examined the distributions of 3 variant alleles, UGT1A1*6, *28, and *27, in 46 Japanese patients with rheumatoid arthritis (RA) who had received tocilizumab therapy for at least 24 weeks, grouped the patients according to their carriage status of these UGT1A1 variants, and determined the frequency of hyperbilirubinemia in each of the groups. Of the 46 patients treated with tocilizumab, 34 maintained normal bilirubin levels after 24 weeks, whereas the remaining 12 developed mild or moderate hyperbilirubinemia. Patients carrying 2 copies of UGT1A1*28 (*28/*28) were more likely to develop hyperbilirubinemia than those without UGT1A1*28. In addition, patients carrying 2 copies of variant alleles, either as homozygotes (UGT1A1*6/*6 or *28/*28) or as compound heterozygotes (UGT1A1*6/*28), were at higher risk of hyperbilirubinemia as compared with those without either UGT1A1*6 or UGT1A1*28 (odds ratio [OR] 28.33; 95% confidence interval [CI] 2.39–336.00; p = 0.005). Multivariate logistic regression analysis confirmed the strong association of tocilizumab-induced hyperbilirubinemia with the presence of 2 copies of variant alleles (OR 25.51; 95% CI 2.35–276.53; p = 0.008), yielding an area under the receiver operating characteristics curve of 0.78 (95% CI 0.60–0.95, p = 0.005). Tocilizumab can induce hyperbilirubinemia in RA patients, especially those carrying UGT1A1*6/*6, *6/*28, and *28/*28 genotypes. Considering this genetic association, it may be unnecessary to withdraw this drug from RA patients in the absence of other signs of hepatic injury. Given that tocilizumab has the potential to inhibit UGT1A1-mediated glucuronidation, however, it may inhibit not only bilirubin metabolism but also UGT1A1-dependent detoxification of drugs, thereby increasing the risk of unwanted adverse events during RA therapy.     

A novel single‐nucleotide polymorphism at the 5′‐flanking region of SAA1 associated with risk of type AA amyloidosis secondary to rheumatoid arthritis

Objective

To address whether the γ haplotype at exon 3 of the SAA1 gene is directly associated with type AA amyloidosis or is merely in linkage with an unknown polymorphism that is primarily associated with disease risk, we examined the SAA1 gene for new polymorphisms.

Methods

We analyzed DNA samples from 44 rheumatoid arthritis (RA) patients with AA amyloidosis (amyloid group), 55 RA patients without AA amyloidosis (RA group), and 58 non‐RA healthy subjects (non‐RA group). We also examined DNA samples from 50 Caucasians to compare linkage disequilibrium relationships involving SAA1 region polymorphisms between Japanese and Caucasoid populations.

Results

We observed 3 novel single‐nucleotide polymorphisms (SNPs) in the 5′‐flanking region of SAA1: −61C/G, −13T/C, and −2G/A. Comparison of allele frequencies and ratios of individuals with particular alleles between the study groups revealed statistically significant differences between the amyloid and RA groups and between the amyloid and non‐RA groups. Statistical analysis revealed that the −13T/C SNP was strongly associated with AA amyloidosis. In addition, we found tight linkage between the −13T allele and the α haplotype, rather than the β haplotype, at exon 3 in the Caucasoid population, while −13T was closely linked to the γ and β haplotypes, rather than the α haplotype, in the Japanese population. Since the linkage disequilibrium relationship was reversed between the Japanese and Caucasoid populations, different exon 3 haplotypes of SAA1 are found to be associated with the risk of AA amyloidosis in different ethnic groups.

Conclusion

Our data suggest that the SAA1 −13T allele, rather than SAA1 exon 3 haplotypes, is primarily associated with AA amyloidosis risk.

     

Relative serum amyloid A (SAA) values: the influence of SAA1 genotypes and corticosteroid treatment in Japanese patients with rheumatoid arthritis

OBJECTIVES: (1) To determine whether serum concentration of serum amyloid A (SAA) protein is influenced by the SAA1 allele in Japanese patients with rheumatoid arthritis (RA) as previously shown in a healthy control group; and (2) to analyse what factors, based on such an allelic bias, influence the relative SAA values of those patients. METHODS: SAA and C reactive protein (CRP) concentrations together with SAA1 genotypes were determined in 316 Japanese patients with RA. The relative SAA values were evaluated as an SAA/CRP ratio. RESULTS: Comparison of the three SAA1 homozygote groups showed that the SAA/CRP ratio was highest in the 1.5/1.5 group (mean 9.0, p<0.01 v the other two homozygote groups) followed by the 1.3/1.3 group (mean 7.2, NS v the 1.1/1.1 group) and the 1.1/1.1 group (mean 4.0). The SAA/CRP ratio was significantly higher in patients receiving corticosteroids regardless of the presence of allele 1.5. No clear differences in the ratio between patients with or without amyloidosis were found. CONCLUSION: The SAA1.5 allele and corticosteroid treatment had a positive influence on SAA concentrations in serum. These findings are important when evaluating SAA concentration in inflammatory diseases and when considering the cause or treatment of amyloidosis.