Related Experiment Videos
Systematic screening for fragile X syndrome in a cohort of 574 mentally retarded children
B Gérard1, M F Le Heuzey, G Brunie
1Laboratoire de Biochimie Génétique, Hôpital Robert Debré, Paris, France.
Insights
This study screened 574 children with mental retardation for fragile X syndrome (FXS). The overall prevalence of FXS was 1.9%, highlighting the need for systematic genetic screening in this population.
Area of Science:
- Genetics
- Pediatrics
- Neurology
Background:
- Fragile X syndrome (FXS) is a leading genetic cause of intellectual disability.
- Accurate diagnosis is crucial for genetic counseling and management.
- Mental retardation is the primary clinical indicator for FXS screening in children.
Purpose of the Study:
- To determine the prevalence of fragile X syndrome in a cohort of children diagnosed with mental retardation.
- To evaluate the utility of a PCR-based screening strategy for FXS diagnosis.
- To assess the justification for systematic FXS screening in intellectually disabled children.
Main Methods:
- A cohort of 574 children with mental retardation (DSM-IIIR) was screened.
- A diagnostic strategy involving initial PCR followed by Southern blotting was employed.
- The cohort comprised 403 boys and 171 girls.
Main Results:
- The overall prevalence of fragile X syndrome was 1.9% (11/574).
- Prevalence was higher in boys (2.5%, 10/403) compared to girls (0.6%, 1/171).
- Clinical signs were often subtle, with mental retardation being the main diagnostic clue.
Conclusions:
- Systematic screening for fragile X syndrome in children with mental retardation is warranted.
- Early and precise diagnosis facilitates effective genetic counseling.
- The PCR-based strategy proved effective for large-scale screening.
Abstract:
In this study, we evaluated the prevalence of the fragile X syndrome in a cohort of 574 mentally retarded children. The only inclusion criterion was the diagnosis of mental retardation according to the DSM-IIIR classification. We used a PCR-based strategy for the diagnosis of fragile X syndrome to facilitate systematic screening. This diagnostic scheme is based on an initial PCR to eliminate most fragile X-negative patients followed by Southern blotting for fragile X syndrome diagnosis. Altogether, 403 boys and 171 girls were tested. The prevalence of this genetic disorder was 1.9% (11/574) in the whole cohort and 2.5% (10/403) in boys. Only one case of fragile X syndrome was detected among the 171 girls tested (0.6%). Clinical examination, especially in the youngest children, was often unremarkable, and the only reason for suspecting fragile X syndrome was the presence of mental retardation. Thus, a systematic screening for the fragile X syndrome in mentally retarded children seems justified because of the importance of a precise diagnosis in genetic counseling.