FMR1 allele frequencies in 51,000 newborns: a large-scale population study in China
Jin-Yu Zhang1,2,3, Ding-Wen Wu1,3, Ru-Lai Yang1,3
1Children's Hospital, School of Medicine, Zhejiang University, Hangzhou, 310052, China.
Insights
This study investigated Fragile X syndrome (FXS) prevalence in China, finding higher rates than previously estimated. FXS screening is recommended for high-risk families.
Area of Science:
- Genetics
- Human Genetics
- Medical Genetics
Background:
- Fragile X syndrome (FXS) is a common cause of mental retardation, linked to CGG-repeat expansion in the FMR1 gene.
- Individuals with premutation or full mutation alleles face risks for psychophysiological disorders and transmitting the condition.
- Previous FMR1 allele frequency data primarily focused on Caucasian populations, lacking large-scale Chinese data.
Purpose of the Study:
- To determine the prevalence of Fragile X syndrome (FXS) in the mainland Chinese population.
- To expand existing sample databases for FXS research.
- To inform potential screening strategies for high-risk families in China.
Main Methods:
- Analyzed FMR1 CGG-repeat sizes in 51,661 newborns (28,114 males, 23,547 females).
- Utilized GC-rich polymerase chain reaction (PCR) and triple repeat primed PCR techniques.
- Assessed a cohort of 33 children with developmental delay for FMR1 mutations.
Main Results:
- CGG repeat frequencies >100 were 1/9371 in males and 1/5887 in females.
- CGG repeat frequencies >54 were 1/1561 in males and 1/1624 in females.
- FMR1 full mutation and premutation were found in 27.27% of children with developmental delay indicators.
Conclusions:
- The study establishes the prevalence of FXS in China, indicating it may be higher than previously thought.
- Findings contribute valuable data to FXS sample databases.
- FXS screening is suggested for high-risk families in China based on these prevalence estimates.
Background:
Fragile X syndrome (FXS), caused by CGG-repeat expansion in FMR1 promoter, is one of the most common causes of mental retardation. Individuals with full mutation and premutation alleles have a high risk of psychophysiological disorder and of having affected offspring. Frequencies of FMR1 alleles in general newborns have been reported in Caucasians but have not been investigated in the large-scale population in the mainland of China.
Methods:
The sizes of FMR1 CGG-repeats were analyzed in 51,661 newborns (28,114 males and 23,547 females) and also in a cohort of 33 children diagnosed with developmental delay using GC-rich polymerase chain reaction (PCR) and triple repeat primed PCR.
Results:
The frequency of CGG repeats > 100 was 1/9371 in males and 1/5887 in females, and the frequency of CGG repeats > 54 was 1/1561 in males and 1/1624 in females. FMR1 full mutation and premutation were identified in 27.27% of children who had Ages and Stages Questionnaire scores less than two standard deviations from the cutoff value.
Conclusions:
Our study revealed the prevalence of FXS in China and improved the sample databases of FXS, suggesting that the prevalence of FXS in Chinese is higher than estimated previously and that FXS screening can be advised to high-risk families.
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