The impact of CGG repeat length in the UTR 5' region of the FMR1 gene in the ovarian reserve and reproductive outcomes of women undergoing assisted reproduction

• Grant number: 20/08643-1
• Support Opportunities: Regular Research Grants
• Start date: August 01, 2021
• End date: January 31, 2024
• Field of knowledge: Health Sciences - Medicine - Medical Clinics
• Principal Investigator: Bianca Alves Vieira Bianco
• Grantee: Bianca Alves Vieira Bianco
• Host Institution: Centro Universitário FMABC (FMABC). Santo André , SP, Brazil
• Associated researchers: Caio Parente Barbosa ; Denise Maria Christofolini ; Fernando Luiz Affonso Fonseca

Abstract

Infertility affects about 20% of couples of reproductive age. Genetic variants may be associated with infertility, among them, the dynamic mutation in the UTR5´ region of the FMR1 gene. Evidence in the literature suggests that the pre-mutation of this gene (55-200 CGG repetitions) interferes with the prenatal development of the oocyte pool, reducing the number of viable oocytes. Women with the pre-mutation have a higher risk of changes in the menstrual cycle, a higher frequency of infertility and a higher risk of early ovarian failure when compared to women with normal alleles. The first step in performing IVF / ICSI treatment is controlled ovarian stimulation to obtain mature oocytes, which is dependent on the ovarian reserve. The response to controlled ovarian hyperstimulation is known to be variable and difficult to predict. Pre-mutation in the FMR1 gene has been associated with decreased ovarian reserve and reproductive results, however, with controversial results in the literature. In addition, the number of CGG repetitions confers a greater risk of decreasing ovarian reserve is still a question to be answered. Based on these findings, the aim of the present study is to evaluate the impact of CGG repeat length in the UTR 5' region of the FMR1 gene in women with alleles classified within the normal range in the ovarian reserve and assisted reproduction outcomes. A cross-sectional study will be carried out with 200 women submitted to IVF/ICSI. The number of CGG repetitions in the FMR1 gene will be investigated by analyzing fragments generated by capillary sequencing. The serum levels of FSH and AMH will be measured in the follicular phase of the menstrual cycle, as well as the count of antral follicles, immediately before the start of ovarian stimulation with gonadotropins. The results of the assisted reproduction treatment (recovered follicles, metaphase II oocytes, number and quality of embryos produced and pregnancy rate) will be collected. Statistical analysis will be performed using the R programming language. (AU)