Received January 31, 2021
Accepted July 31, 2021

Objective: Our study aimed to identify mutations in the FMR1 gene in a group of Brazilian women diagnosed with primary ovarian insufficiency (POI). Method: This cross-sectional study included patients under 40 years of age with confirmed POI. Is a convenience sample during the period from June 2017 to December 2018 from a University Hospital in Curitiba, Brazil. Genomic DNA was extracted and analyzed by FragilEase™ PCR kit (PerkinElmer), a commercial available test that enables the quantification of the numbers of CGG trinucleotide repeat expansion in FMR1 gene. Results: Were included 52 patients, with average age was 35.8 ± 3.97 years. Among the participants, 50/52 (96.1%) had normal alleles between 18 and 43 CGG repeats. The most frequent allele sizes found in the study were 28 CGG repeats and 30 CGG repeats. Two patients (3.8%) presented mutations in the FMR1 gene. The first presented alleles with 19/97 CGG repeats and was classified as a premutation carrier for FXS and had a son with cognitive deficit. In the second case, alleles with 21/45 CGG repeats and was classified as having a gray zone. Conclusion: In our study we identified 3.8% patients with mutations in the FMR1 gene in a group of women with POI. The most frequent allele sizes found were 28 CGG repeats and 30 CGG repeats.