Hormone replacement therapy and the risk of reproductive cancers

Age at menarche and menopause is not associated with two common genetic variants in the methylenetetrahydrofolate reductase (MTHFR) gene

OBJECTIVES

The study aimed at investigating the independent and the combined effects of the two common genetic variants in the methylenetetrahydrofolate reductase (MTHFR) gene, 677C > T and 1298A > C, and their interaction with lifestyle factors on timing of menarche and natural menopause.

METHODS

Postmenopausal women (N = 792) were assessed for the association of the two genetic variants with age at menarche (AM). A subsample of 578 of them who had a natural menopause were further investigated for the association of the two genetic variants with age at natural menopause (ANM). Genotyping was done by means of the TaqMan(®) allelic discrimination method. The effect of genetic variants and of lifestyle factors on AM and ANM were calculated by linear regression models.

RESULTS

The study revealed no association between the individual or combined effects of the two genetic variants and AM or ANM. The genetic variant 677C > T showed a significant interaction effect with duration of breastfeeding on ANM (p = 0.047).

CONCLUSION

We were unable to replicate previous findings suggesting that the MTHFR gene influences the onset of menarche and natural menopause. The interaction effect between the 677C >T genetic variant and duration of breastfeeding on the timing of natural menopause requires further investigation.

Evaluation of PvuII and XbaI polymorphisms in the estrogen receptor alpha gene (ESR1) in relation to menstrual cycle timing and reproductive parameters in post-menopausal women

OBJECTIVE

To evaluate the association of -397T>C and -351A>G single nucleotide polymorphisms (SNPs) - also called PvuII and XbaI, respectively - located on estrogen receptor alpha (ERS1) gene with age at menarche, menopause onset, fertility and miscarriage in a population of post-menopausal women.

STUDY DESIGN

Cross-sectional study with 273 healthy, high miscegenated, post-menopausal women (mean age of 63.1±9.7 years old). Subjects were genotyped for PvuII and XbaI SNPs by PCR-RFLP and confirmed by automatic sequencing. Reproduction informations (age at menarche, age at menopause, number of pregnancies, fertility rate and miscarriages) were obtained by retrospective study using a questionnaire.

RESULT(S)

Age at menarche, menopause onset, number of pregnancies, total fertility rate, and parity did not seem to be influenced by any of the studied genotypes (chi-square, p>0.05). However, women carrying the xx genotype showed a 44% higher chance of miscarriage, whereas this value did not trespass 16% for any other genotype analyzed. It has been also observed a higher occurrence of miscarriage in association with combined xxpp genotype of ERS1 gene (chi-square, p<0.01).

CONCLUSION(S)

The present data indicate that the studied SNPs on ERS1 gene do not influence the menstrual cycle timing and parity but there is a strong relationship between the xx ERS1 SNP genotype and the incidence of miscarriage in the post-menopausal population analyzed.