Katja Lottermoser, Rainer Dsing, Peter Ervens, Brigitte Koch, Thomas Brning, Agapios Sachinidis, Hans Vetter, and Yon Ko conducted a study on the effect of the PAI-1 4G/5G genotype on longevity among 205 subjects aged 80 years and older. They used a light-cycler assisted method to analyze the PAI-1 4G/5G polymorphism on the gene level. They found that in these 205 persons, the 4G/5G allele was found in 96 persons (47%), the 4G/4G variant in 62 (30%), and the 5G/5G allele in 47 (23%). These data are similar to the allele distribution described in other large cohorts not restricted to old age. Thus, the results of this study do not suggest an important contribution of the PAI-1 genotype to total mortality.

The primary function of PAI-1 is to regulate fibrinolysis. Elevated levels of PAI-1 may play a role in the development of cardiovascular disease. Studies on the significance of the 4G/5G polymorphism as a risk predictor for individuals with or without atherothrombotic disease have revealed conflicting results. Therefore it remains unclear whether the PAI-1 polymorphism is associated with an increased risk in morbidity and mortality.

The determination of this PAI-1 polymorphism may have important implications in the early detection of asymptomatic patients who have an increased risk of developing cardiovascular disease. The study evaluated the 4G/5G PAI-1 polymorphism in 205 persons aged 80 years or older to evaluate whether aging is associated with the predominance of a certain PAI-1 genotype, possibly indicating the selection of a favorable allele.

The accurate assessment of its age dependency and proportional distribution in the population could provide additional information on the (patho)physiological relevance of the 4G/5G polymorphism. The allele frequencies were nearly identical among subjects with and without a history of cardiovascular disease within the study group.

Several sequence variations in the promoter region of the PAI-1 gene, especially the 4G/5G polymorphism, have been described. In vitro studies suggest that the 4G allele is associated with higher PAI-1 activity than the 5G allele. One possible mechanism may be derived from the finding that while both alleles bind a transcriptional activator, the 5G allele contains an additional binding site for a DNA-binding protein that could be a transcriptional repressor. In the absence of bound repressor, the basal level of PAI-1 transcription is increased. As gene variants of PAI-1 account for a significant portion of the interindividual variability in circulating PAI-1 antigen concentrations in the general population, there is increasing interest in determining the genotype of PAI-1. In a large cohort of men in the United States aged 40-84 years, the overall allele distribution has been described.Reported as approximately 25% 4G/4G, 25% 5G/5G, and 50% 4G/5G genotypes [20], real-time PCR fluorescence (F) cycles, melting curves, and fluorescence (F)-dF/dT reference values were used to determine the distribution of the 4G/5G alleles among cohorts in the United States, Japan, and Europe. A similar distribution pattern was observed in our group of 205 elderly subjects (Table 2). Subgroup analysis comparing the frequency of the PAI-1 4G/5G alleles between subjects with and without a history of cardiovascular disease did not yield any significant differences in allele frequencies among the two groups (Table 2). Thus, homozygosity for the 4G allele, despite its association with impaired fibrinolysis, is compatible with reaching old age. This contrasts with the findings of a previous study [21], which demonstrated a higher proportion of the 4G allele and the homozygous 4G/4G genotype in centenarians than in young individuals (P = 0.021 and P = 0.049, respectively). The latter results suggest an even better survival for individuals with the PAI-1 4G genotype despite its association with impaired fibrinolysis. Individuals with the homozygous 4G/4G genotype did not suffer more frequently from stroke or myocardial infarction, which is intriguing as high PAI-1 is considered a predictor of myocardial infarction in young men [18]. Despite this fact, the corresponding genetic marker is more frequent in the studied subjects who have escaped major age-related atherothrombotic disease and reached old age.

Fig. 1AC shows analysis of the PAI-1 promoter region covering the 4G/5G polymorphic site using a real-time PCR approach. Real-time PCR of PAI-1 4G/5G polymorphism was conducted, and melting curves of 30 samples were obtained (fluorescence over time). The first differentiation of the fluorescence (F) over time (T; dF/dT) was also carried out. The melting maximum of the 5G-hybridization probe is 59.5°C in the case of the 4G/4G genotype, 59.5°C in the case of the 4G/5G genotype, and 65.0°C in the case of the 5G/5G genotype.

Table 2 shows the genotype distribution of the PAI-1 4G/5G polymorphism among octogenarians. The table indicates that there were no significant differences in the frequency of PAI-1 4G/5G alleles between subjects with and without a history of cardiovascular disease. Table 3 demonstrates the genotype distribution of PAI-1 4G/5G polymorphism among various cohorts (percentages).