Clinical Application of Long-Read Sequencing for FMR1 Gene Mutation Detection in Populations From Shandong, China.

BACKGROUND

Fragile X syndrome (FXS) is a common inherited intellectual disability. In this study, long-read sequencing was used for the FMR1 gene detection.

METHODS

Men with familial inherited intellectual disability and women with indications for FXS screening were defined as high-risk populations and were included in this study along with non-high-risk reproductive-aged women. PCR-capillary electrophoresis was used for preliminary screening of non-high-risk reproductive-aged women, and long-read sequencing was performed on abnormal samples and samples from high-risk populations. Prenatal diagnosis using long-read sequencing was performed for pregnant women in need.

RESULTS

The prevalence of mutation in high-risk females was 3.10% (7/226). 3 mutations were detected in male samples, with a mutation ratio of approximately 8.3% (3/36). The three most common CGG repeats were 29, 30, and 36, respectively. Analysis of AGG interruption pattern in 242 samples identified 908 AGG interruptions, involving 67 different patterns. The most frequent AGG interruption pattern was (CGG)9AGG(CGG)9AGG(CGG)9. Furthermore, long-read sequencing was successfully applied for prenatal diagnosis in two pregnant women, and dynamic mutation of CGG repeat was detected within one family.

CONCLUSION

Long-read sequencing-based assay cannot only accurately detect CGG repeat and AGG interruption, but also simultaneously identify other abnormalities of the FMR1 gene. Long-read sequencing offers a broader detection scope and better characterization of FXS-related genetic features.