Genetic heterogeneity of the 5' uncoding region of the catalase gene in Hungarian acatalasemic and hypocatalasemic subjects

Frequency of polymorphism -262 c/t in catalase gene and oxidative damage in Slovak children with bronchial asthma

INTRODUCTION

Bronchial asthma is a complex disease in which genetic factors, environmental factors and oxidative damage are responsible for the initiation and modulation of disease progression. If antioxidant mechanisms fail, reactive oxygen species damage the biomolecules followed by progression of the disease. Catalase is one of the most important endogenous enzymatic antioxidants. In the present study, we examined the hypothesis that increased oxidative damage and polymorphism in the CAT gene (-262 promoter region, C/T) are associated with childhood bronchial asthma.

PATIENTS AND METHODS

Genotyping of the polymorphisms in the CAT gene in healthy (249) and asthmatic children (248) was performed using polymerase chain reaction-restriction fragment length polymorphism. Markers of oxidative damage: content of sulfhydryl groups and thiobarbituric acid-reactive substances were determined by spectrophotometry in children.

RESULTS

The TT genotype of catalase was more frequent among the asthmatic patients (22.6%) than in healthy children (4.8%) (odds ratio=5.63; 95% confidence interval=2.93-10.81, P<.001). The amount of sulfhydryl groups decreased significantly and conversely, the content of thiobarbituric acid-reactive substances increased significantly in bronchial asthma and in catalase TT genotype compared to other catalase genotypes of this gene.

CONCLUSIONS

These results suggest that catalase polymorphism might participate in development of bronchial asthma and in enhanced oxidative damage in asthmatic children. Genetic variation of enzymatic antioxidants may modulate disease risk.

The spectra of point mutations in vertebrate genomes

In spite of the importance of point mutations for evolution and human diseases, their natural spectrum of incidence in different species is not known. Here I propose to determine these spectra by comparing consecutive sequence periods in stretches of repetitive DNA. The article presents the analysis of more than 51,000 such point mutations identified by this approach in the genomes of human, chimpanzee, rat, mouse, pufferfish, zebrafish, and sea squirt. I propose to explain the observed spectra by auto-mutagenic mechanisms of genome variation involving the inter-conversions of nucleotides, single base-pair inversions and their combinations.

Gene polymorphisms of oxidative stress enzymes: prediction of elderly renutrition

BACKGROUND

The free radical theory of aging suggests that damage caused by oxidative stress leads to impaired physiologic functions. This damage is stemmed by an adequate antioxidant status, which minimizes the occurrence of infection, thus potentially playing a role in improving nutritional status. The role played by genetic factors remains unknown.

OBJECTIVE

The aim of this study was to investigate whether a single nucleotide polymorphism (SNP) of a gene coding for endogenous antioxidant enzymes could influence either nutritional status or renutrition process in an elderly population.

DESIGN

Nutritional and inflammatory status were studied in 77 elderly outpatients and in 99 malnourished elderly inpatients over 6 wk of health care treatment. Renutrition efficiency was evaluated with use of the ratio between initial transthyretinemia and 6-wk variation. A genetic study was performed on superoxide dismutase (Ala-9Val), glutathione peroxidase (Pro197Leu), and catalase (from promoter to the first intron).

RESULTS

Among the SNPs studied, the G-844A, A-89T, and C-20T catalase SNPs could each be markers predicting renutrition efficiency. These catalase mutant alleles were associated with a lower efficiency of renutrition in malnourished elderly subjects, regardless of initial nutritional and inflammatory status. Genotyping one of these catalase SNPs could make it possible to identify a high-risk subpopulation of mutant allele carriers within the elderly polypathological population.

CONCLUSION

In a malnutrition setting, this subpopulation should be given personalized health care, including a strengthened refeeding program. Thus, catalase genotyping could enable earlier recovery of satisfactory nutritional status and thus avoid the consequences of malnutrition, which are especially deleterious in the elderly.

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.

Catalase and PPARgamma2 genotype and risk of rheumatoid arthritis in Koreans

Catalase (CAT) and peroxisome proliferator activated receptor-gamma2 (PPARgamma2) are important regulators of oxidative stress and inflammation, and may contribute to the development of rheumatoid arthritis (RA). We investigated the association between CAT and PPARgamma2 genotypes and risk and severity of RA using 474 cases and 400 controls. Genotyping for the -262C-->T polymorphism of CAT and the Pro12Ala polymorphism of PPARgamma2 was performed by PCR-RFLP analysis. Severity of RA was assessed by the anatomical stage according to Steinbrocker, and a Korean language version of a Health Assessment Questionnaire (KHAQ). No association was observed between CAT and PPARgamma2 genotypes and risk of RA. Our results suggest that genetic polymorphisms of CAT and PPARgamma2 do not play a significant role in the susceptibility to RA among Koreans.

Genetic association of the catalase gene (CAT) with vitiligo susceptibility

Vitiligo susceptibility is a complex genetic trait that may involve genes important for melanin biosynthesis, response to oxidative stress, and/or regulation of autoimmunity, as well as environmental factors. We report here case-control and family-based association studies for the catalase gene (CAT) in vitiligo patients. The CAT gene was selected as a candidate gene because of the reduction of catalase enzyme activity (EC 1.11.1.6) and concomitant accumulation of excess hydrogen peroxide observed in the entire epidermis of vitiligo patients. One of three CAT genetic markers studied was found to be informative for genotypic analysis of Caucasian vitiligo patients and control subjects. Both case/control and family-based genetic association studies of the T/C single nucleotide polymorphism (SNP) in exon 9 of the CAT gene, which is detectable with the restriction endonuclease BstX I, suggest possible association between the CAT gene and vitiligo susceptibility. The observations that T/C heterozygotes are more frequent among vitiligo patients than controls and that the C allele is transmitted more frequently to patients than controls suggest that linked mutations in or near the CAT gene might contribute to a quantitative deficiency of catalase activity in the epidermis and the accumulation of excess hydrogen peroxide (H2O2). The CAT gene may, therefore, be a susceptibility gene in some vitiligo patients, further supporting the epidermal oxidative stress model for vitiligo pathogenesis.

A new type of inherited catalase deficiencies: its characterization and comparison to the Japanese and Swiss type of acatalasemia

Thirteen Hungarian families that exhibited inherited catalase deficiencies have been detected. Differences between the deficiencies reported from Hungary and the previously reported Swiss acatalasemia were characterized using biochemical analysis of the catalase proteins. Molecular biological methods were used to compare the previously reported types of catalase deficiencies in Japan and the Hungarian deficiencies. Three mutations (a GA insertion in exon 2, a G insertion in exon 2, and a T to G substitution in intron 7) are responsible for decreased catalase activity in 7 of the 13 Hungarian kindreds; the other 6 families have not yet been characterized. These are not the mutations observed in Japan. Changes in lipid and carbohydrate metabolism and the high incidence (12.7%) of diabetes mellitus in the Hungarian kindreds suggest that individuals with inherited catalase deficiency are at risk of atherosclerosis and diabetes mellitus. The Hungarian subjects were detected during screening of a large population for catalase activity; no overt disease state was associated with the deficiencies. We hypothesize that the increased risk of disease may be due to prolonged exposure to elevated levels of blood hydrogen peroxide due to the lack of normal removal of hydrogen peroxide by blood catalase.

A novel catalase mutation detected by polymerase chain reaction-single strand conformation polymorphism, nucleotide sequencing, and western blot analyses is responsible for the type C of Hungarian acatalasemia

Polymerase chain reaction-single strand conformation polymorphism (PCR-SSCP) screening was used for searching mutations of the catalase gene in two Hungarian hypocatalasemic families. A syndrome-causing mutation was found in a PCR product containing exon 7 and its boundaries. Nucleotide sequence analyses detected a G to T substitution at position 5 of intron 7. The effect of this splice site mutation was confirmed by Western blot analyses demonstrating a decreased catalase protein level in these patients. These findings represent a novel type (C) of catalase mutations in the Hungarian acatalasemic/hypocatalasemic patients.

Anovel catalase mutation (a GA insertion) causes the Hungarian type of acatalasemia

Acatalasemia, a deficiency of enzyme catalase, is an autosomal recessive syndrome with an incidence of 5:106 in Hungary. We have examined the first Hungarian acatalasemic family for the disease-causing mutation. All exons of the catalase gene were screened by PCR-SSCP, PCR-heteroduplex, and nucleotide sequence analysis. The heteroduplex formation detected in exon 2 was verified by nucleotide sequence analysis. We found a GA insertion at nucleotide position 138, increasing the GA repeat number from 4 to 5. This GA insertion caused a frameshift in the amino acid sequence from position 68 to 133 and generated a TGA terminating codon at amino acid position 134. This truncated protein lacks the essential amino acid (histidine 74) in the active center. This finding can explain the decreased blood catalase activity in the Hungarian acatalasemic family.