3. Results 

The most common alleles were the 19-repeat allele (39.12%) and the 21-repeat allele (26.14%). The genotype distribution followed Hardy-Weinberg Equilibrium in both groups and when stratified by gender (p > 0.05). There were no significant differences in genotype distribution or allele frequencies between the two groups when considered as a whole or when stratified by gender.

However, when comparing the distributions of all possible genotypes in male participants with one allele having 21 repeats, there was a significant difference in the distribution of the 18/21 genotype between male elderly and male control groups (11.11 vs. 5.45%, p = 0.011). After Bonferroni correction for multiple tests, the result was no longer significant.

4. Discussion 

This study found no significant association between the microsatellite polymorphism in the IGF1 gene promoter and longevity in a Han Chinese population. However, there was a significant difference in the distribution of the 18/21 genotype between male elderly and male control groups, although this result did not remain significant after correction for multiple tests.

The study had some limitations, including a relatively small sample size and a lack of information on other potential genetic or environmental factors that may affect longevity. Further studies with larger sample sizes and more comprehensive analyses are needed to fully understand the potential role of this microsatellite polymorphism in longevity.The comparison of haplotype distribution in the elderly and control groups is presented. The haplotype distribution is shown for all, female, and male participants. The number of repeats in the microsatellite locus is represented by the number in the haplotype. The total number of participants is less than the whole population because of missing data. There is a difference in allele frequencies between the Chinese and Caucasian populations, but no significant difference within the Han population between the elderly and control groups, even when stratified by gender. Therefore, no specific alleles at this locus are associated with longevity in this Han population. In males, the 18/21 genotype was more frequent in the elderly group than in the control group, but future studies with more loci in the long haplotype block are needed to test the hypothesized linkage between the 18/21 genotype and functional loci.

To explore the potential role of the microsatellite locus, we compared genotype frequencies in elderly and control groups depending on 19-repeat and 21-repeat (the two most common alleles) to define categories. No single haplotype was positively associated with longevity. The haplotype block is long enough that more SNPs from this region could be included for testing if a potential functional site exists.

In summary, no association was found between the microsatellite polymorphism in IGF1 gene promoter and longevity in a Han Chinese population. The possibility of a functional site linked to the microsatellite locus (especially in men) deserves future studies.There are several references listed in this text, but it is difficult to determine the context or purpose of the references without additional information. Therefore, no changes will be made to the content of the text. However, some formatting changes will be made for clarity and readability: