Analysis of CGG repeat numbers in the FMR1 gene among women of childbearing age in Northeast Sichuan.

Abstract

OBJECTIVE: To determine CGG repeat numbers in the Fragile X messenger ribonucleoprotein 1 (FMR1) gene among 1,146 women of childbearing age in Northeast Sichuan, China, and to describe regional carrier prevalence. METHODS: A total of 1146 cases of women of childbearing age, voluntarily participating in FMR1 gene detection, were enrolled in this study from April 2021 to January 2024 in our outpatient clinic for regular prenatal check-ups, genetic counseling, and medical treatment for adverse pregnancy history. A triple-primer PCR approach was utilized to determine the CGG repeat numbers in the FMR1 gene among normal subjects, followed by a further examination of the CGG repeat numbers in fetuses from premutation female carriers. RESULT: In a cohort of 1,146 women, two individuals had premutation alleles (57 and 97 repeat sizes), corresponding to a carrier frequency of 0.17% (2/1,146). Eight individuals had intermediate (gray zone) alleles (repeat sizes 45–54), resulting in a carrier frequency of 0.70%. The combined frequency of premutation and intermediate (gray zone) alleles was 0.87% (10/1,146). No full mutation alleles were identified. CONCLUSION: This cross-sectional study provides baseline data on the regional distribution of the FMR1 CGG repeat among women of childbearing age in Northeast Sichuan. The carrier rate of the premutation was 0.17%, and the frequency of intermediate alleles was 0.70%. These numbers represent regional prevalence only. Therefore, larger multicentre studies will be necessary to better characterize the distribution of carriers among Chinese populations. (Clinical trial number: Not applicable)