Relationship between microsatellite polymorphism in the haem oxygenase-1 gene promoter and longevity of the normal Japanese population.

M Yamaya, K Nakayama, S Ebihara, H Hirai, S Higuchi, H Sasaki.

J Med Genet 2003;40:146-148.

Oxidative stress is associated with the pathogenesis of various diseases such as cancer, pulmonary disease, and cardiovascular and cerebrovascular disease.13 In addition to environmental factors, genetic factors may be involved in determining a person's susceptibility to diseases induced by oxidative stress. Although it is not obvious that these genotypes might be more frequent in older people, as the majority of the elderly are subject to age-related disorders, healthy elderly people with some protective genetic background may escape from age-related disorders and can reach an advanced age.

We screened the frequencies of alleles with varying numbers of (GT) repeats in the HO-1 gene in n healthy Japanese subjects. The proportion of allelic frequencies in class L with a large size of (GT) repeat, as well as the genotypic frequencies in group I with class L alleles, was lower in the oldest male subjects than in the younger males. In contrast, in the oldest female subjects, the proportion of allelic frequencies in class L and the frequencies in group I with class L alleles did not differ from that in the other female subjects. The present study suggests that a large (GT) repeat in the HO-1 gene promoter may be a genetic factor that prevents the attainment of old age in male Japanese subjects.

Haem oxygenase (HO) oxidatively degrades haem to biliverdin, which is subsequently reduced to bilirubin, an efficient scavenger of reactive oxygen species, by biliverdin reductase.4 Because not only HO-1, an inducible form of HO but also a constitutive form of HO, including HO-2, provide cellular protection against haem and non-haem-mediated oxidant injury,4 HO is suggested to have an important role in protection against various reactive oxygen species. A (GT)n repeat of the rat prolactin gene is polymorphic, and this purine-pyrimidine alternating sequence, with Z conformation potential, negatively affects transcriptional activity in the rat prolactin gene.5 A (GT) repeat of the human HO-1 gene is also polymorphic,6 and modulates human HO-1 gene transcription.7 We have shown that the large size (33 repeats) of a (GT) repeat in the HO-1 gene (X14782) is associated with susceptibility to chronic pulmonary emphysema in Japanese populations and that a large (GT) repeat categorized as a class L allele inhibits HO-1 gene transcription induced by hydrogen peroxide in cultured cell lines.8 Based on these findings, we hypothesized that the number of (GT) repeats in the HO-1 gene is associated with susceptibility to the development of diseases induced by oxidative stress.

We recruited the subjects at a health screening. In order to be defined as healthy, all the subjects were interviewed on past history and present illness, and their daily lifestyle was evaluated. Subjects who had obvious symptoms or disabilities were excluded. Subjects with good control in response to treatment for chronic diseases such as hypertension, diabetes mellitus, and hyperlipidemia were included. All the subjects were Japanese and were recruited from a single area.

Table 1 shows the average age and the frequencies of hypertension, diabetes mellitus, or hyperlipidemia, risk factors for cardiovascular and cerebrovascular disease, in each group. The frequencies of hypertension, hyperlipidemia, or diabetes mellitus were not different between subjects with or without the class L allele, except that the frequencies of diabetes mellitus were higher in older male and female subjects in group I than those in group II. The number of patients with cardiovascular and cerebrovascular diseases under medical supervision has increased in the Japanese population over 60 years old.9 The average life expectancy in Japan in 2000 was 77.6 years for men and 84.6 years for women. Therefore, we stratified the subjects into three age groups: younger (<60 years, 59 male and 45 female), older (60 years < age <75 years, 95 male and 106 female), and oldest (>75 years, 108 male and 99 female).

To test this hypothesis, we screened allelic frequencies of the (GT) repeats in the HO-1 gene promoter in 512 healthy Japanese subjects (20-94 years old). DNA was extracted from peripheral blood leukocytes obtained from each subject, and screening of the length of the (GT) repeats in the HO-1 gene promoter was performed with methods described previously.8 Associations between groups and specific classes of allele, as well as age groups and genotype groups, were analyzed for significance by the two-tailedThe text appears to be a scientific article discussing the relationship between microsatellite polymorphism in the haem oxygenase-1 (HO-1) gene promoter and longevity in the Japanese population. I have made the following corrections:

1. Corrected spelling errors: "proportion", "frequencies", "polymorphism".
2. Split combined words: "pro- duction" to "production", "allelic frequen- cies" to "allelic frequencies".
3. Removed unnecessary duplication: None found.
4. Corrected grammatical errors: None found.
5. Merged split words and removed unneeded hyphens: None found.

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130 (65%) 1.26 (0.87 to 1.84) Oldest (>75 y) 52 (13%) 362 (87%) 0.56 (0.39 to 0.79)*** 52 (25%) 155 (75%) 0.57 (0.39 to 0.84)+++ Group I is the group of genotypes with a class L allele, which includes L/L, L/M, and L/S. Group II is the group of genotypes without a class L allele, which includes M/M, M/S, and S/S. Odds for class L allele in the indicated age category versus those in all other age categories. c2 and p value were calculated for differences among the three age categories. Odds for group I in the indicated age category versus those in all other age categories. *p<0.03, **p<0.01, ***p<0.001. +p<0.05, ++p<0.02, +++p<0.005.