Association of rheumatoid arthritis with HLA-DR1 and HLA-DR4 in Hungary.

Susceptibility to and outcome for rheumatoid arthritis (RA) have been associated with particular HLA-DR alleles, but these alleles vary among ethnic groups and geographic areas. The frequency of HLA-DR1 (HLA-DRB1*0101, DRB1*0102) and HLA-DR4 (DRB1*0401, DRB1*0404) alleles is elevated among Caucasian patients with RA. We studied a northeastern Hungarian population of RA patients to determine the frequency of HLA-DR1 and HLA-DR4 phenotypes in this population and to compare it with healthy control subjects, as well as to investigate whether the presence of these alleles could be a marker for RA. We performed HLA-DRB1 genotyping (DRB1*01-DRB1*16) in 83 RA patients and 55 healthy controls using polymerase chain reaction with sequence-specific primers (PCR-SSP). In the case of HLA-DR1- or HLA-DR4-positive patients, the DR1 and DR4 subtypes were also determined. The frequency of HLA-DR4 alleles was significantly higher in RA patients than in controls (31.3 vs. 10.9%; P <.05). HLA-DR1, in particular, tended to be more frequent in patients than in controls (32.5 vs. 18.1%). Among the HLA-DR4 subtypes, DRB1*0401 and DRB1*0404 were the most common alleles found in both groups. However, no significant differences were seen in the frequency of HLA-DRB1*0401 and HLA-DRB1*0404 between RA patients and controls. In contrast, HLA-DRB1*0405 and HLA-DRB1*0408 were significantly more common in RA patients than in control subjects. Among HLA-DR1 subtypes, the DRB1*0101 allele was most commonly detected, but HLA-DRB1*0101 as well as DRB1*0102 and DRB1*0105 were similarly frequent in RA patients and controls. HLA-DR12 was more common among controls than in RA patients (18.1 vs. 0%; P <.05). Our results generally agree with the findings in other Caucasian populations. Nonetheless, we found differences in the frequency of HLA-DR1 and HLA-DR4 subtypes among Hungarian patients compared with reports from other geographic regions (e.g., Finland and Asia). Our data suggest that in northeastern Hungary, HLA-DR4 as well as its subtypes DRB1*0405 and DRB1*0408 may be involved in susceptibility to RA, but HLA-DR1 may not. In addition, the presence of HLA-DR12, at least in Hungary, may protect from this disease.

Catalase enzyme mutations and their association with diseases.

Enzyme catalase seems to be the main regulator of hydrogen peroxide metabolism. Hydrogen peroxide at high concentrations is a toxic agent, while at low concentrations it appears to modulate some physiological processes such as signaling in cell proliferation, apoptosis, carbohydrate metabolism, and platelet activation. Benign catalase gene mutations of 5' noncoding region (15) and intron 1 (4) have no effect on catalase activity and are not associated with disease. Catalase gene mutations have been detected in association with diabetes mellitus, hypertension, and vitiligo. Decreases in catalase activity in patients with tumors is more likely to be due to decreased enzyme synthesis rather than to catalase mutations.Acatalasemia, the inherited deficiency of catalase has been detected in 11 countries. Its clinical features might be oral gangrene, altered lipid, carbohydrate, homocysteine metabolism and the increased risk of diabetes mellitus. The Japanese, Swiss, and Hungarian types of acatalasemia display differences in biochemical and genetic aspects. However, there are only limited reports on the syndrome causing these mutations. These data show that acatalasemia may be a syndrome with clinical, biochemical, genetic characteristics rather than just a simple enzyme deficiency.

Vitamin D receptor gene polymorphism in rheumatoid arthritis and associated osteoporosis.

Rheumatoid arthritis (RA) is commonly associated with decreased bone mineral density (BMD) due to numerous factors. BsmI polymorphism of the vitamin D receptor (VDR) gene has been implicated in the pathogenesis of osteoporosis. Vitamin D has several immunomodulatory effects and thus may play a role in the course of arthritis. However, little data is available on the possible relationship between RA and VDR gene polymorphisms. In this study, the frequency of BsmI polymorphism genotypes were compared with that found in other countries. In this study, 64 RA patients and 40 healthy controls were tested for VDR gene BsmI polymorphism genotypes. Frequencies of B and b alleles were associated with markers of bone metabolism and RA. Among control subjects, the frequency of the BB genotype is relatively high (27.5%). In RA with secondary osteopenia/osteoporosis the BB genotype was more rare, the bb was more common than in control subjects. Markers of bone metabolism were associated with the B allele. RA patients carrying the B allele had lower BMD and increased bone loss over 1 year. The B allele was also correlated with increased osteoclast and osteoblast function, as determined by the assessment of biochemical markers of bone metabolism. Rheumatoid factor titer, which is an independent marker for disease progression in RA, was higher in bb patients. Our data suggest, that the imbalance in B and b allele expression may be involved in the pathogenesis of RA-associated osteoporosis. The possible involvement of vitamin D and VDR gene polymorphisms in the development and progression of RA needs further elucidation.

Simple PCR heteroduplex, SSCP mutation screening methods for the detection of novel catalase mutations in Hungarian patients with type 2 diabetes mellitus.

BACKGROUND: The enzyme catalase is the main regulator of hydrogen peroxide metabolism. Deficiency of catalase may cause high concentrations of hydrogen peroxide and increase the risk of the development of pathologies for which oxidative stress is a contributing factor, for example, type 2 diabetes mellitus. Catalase deficiency has been reported to be associated with increased frequency of diabetes mellitus in a cohort of patients in Hungary. In this cohort, the majority of mutations in the catalase gene occur in exon 2. METHODS: Type 2 diabetic patients (n=308) were evaluated for mutations in intron 1 (81 bp), exon 2 (172 bp) and intron 2 (13 bp) of the catalase gene. Screening for mutations utilized PCR single-strand conformational polymorphism (SSCP) and PCR heteroduplex methods. Verification of detected mutations was by nucleotide sequence analysis. RESULTS: A total of 11 catalase gene mutations were detected in the 308 subjects (3.57%, p<0.001). Five of the 11 were at two previously reported mutation sites: exon 2 (79) G insertion and (138) GA insertion. Six of the 11 were at five previously unreported catalase mutation sites: intron 1 (60) G-->T; intron 2 (7) G-->A and (5) G-->C; exon 2 (96) T-->A; and exon 2 (135) T-->A. The novel missense mutations on exon 2 (96 and 135) are associated with 59% and 48% decreased catalase activity, respectively; the novel G-->C mutation on intron 2 (5) is associated with a 62% decrease in catalase activity. Mutations detected on intron 1 (60) and intron 2 (7) showed no change in catalase activity. The G-->C mutation on intron 2 (5) might be a splicing mutation. The two missense mutations on exon 2 (96) and (135) cause substitutions of amino acids 53 (Asp-->Glu) and 66 (Glu-->Cys) of the catalase protein. These are close to amino acids that are important for the binding of heme to catalase, 44 (Val) and 72-75 (Arg, Val, Val, His). Changes in heme binding may be responsible for the activity losses. CONCLUSION: Mutations that cause decreased catalase activity may contribute to susceptibility to inherited type 2 diabetes mellitus. Exon 2 and neighboring introns of the catalase gene may be minor hot spots for type 2 diabetes mellitus susceptibility mutations.

Detection of a novel familial catalase mutation (Hungarian type D) and the possible risk of inherited catalase deficiency for diabetes mellitus.

The enzyme catalase is the main regulator of hydrogen peroxide metabolism. Recent findings suggest that a low concentration of hydrogen peroxide may act as a messenger in some signalling pathways whereas high concentrations are toxic for many cells and cell components. Acatalasemia is a genetically heterogeneous condition with a worldwide distribution. Yet only two Japanese and three Hungarian syndrome-causing mutations have been reported. A large-scale (23 130 subjects) catalase screening program in Hungary yielded 12 hypocatalasemic families. The V family with four hypocatalasemics (60.6 +/- 7.6 MU/L) and six normocatalasemic (103.6 +/- 23.5 MU/L) members was examined to define the mutation causing the syndrome. Mutation screening yielded four novel polymorphisms. Of these, three intron sequence variations, namely G-->A at the nucleotide 60 position in intron 1, T-->A at position 11 in intron 2, and G-->T at position 31 in intron 12, are unlikely to be responsible for the decreased blood catalase activity. However, the novel G-->A mutation in exon 9 changes the essential amino acid Arg 354 to Cys 354 and may indeed be responsible for the decreased catalase activity. This inherited catalase deficiency, by inducing an increased hydrogen peroxide steady-state concentration in vivo, may be involved in the early manifestation of type 2 diabetes mellitus for the 35-year old proband.