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FRAXE mutation in mentally retarded patients using the OxE18 probe
M V Mulatinho1, J C Llerena, M M Pimentel
1Department of Cell Biology and Genetics, Universidade do Estado do Rio de Janeiro (UERJ), Rio de Janeiro, Brazil.
International Journal of Molecular Medicine
|December 22, 1999
Summary
Molecular testing revealed no FRAXE expansions in 144 patients negative for Fragile X syndrome (FRAXA). This study established a reliable method for simultaneously screening both FRAXA and FRAXE fragile sites.
Area of Science:
- Human Genetics
- Molecular Biology
- Cytogenetics
Background:
- The folate-sensitive fragile sites FRAXA and FRAXE are located on the human X chromosome.
- While cytogenetically similar, molecular methods allow differentiation and diagnosis of these fragile X conditions.
- Fragile X syndrome (FRAXA) is caused by expansions in the FMR1 gene.
Purpose of the Study:
- To screen 144 patients, negative for FMR1 gene expansions (FRAXA), for FRAXE expansions.
- To evaluate the efficacy of a molecular protocol for detecting FRAXE mutations.
- To establish a routine laboratory method for simultaneous FRAXA and FRAXE testing.
Main Methods:
- Screening for FRAXA involved EcoRI digests on Southern blots hybridized with the StB12.3 probe.
- FRAXE mutation analysis used HindIII digests and probing with OxE20, or EcoRI digests with the OxE18 probe.
- DNA samples from 144 patients referred for fragile X testing were analyzed.
Main Results:
- None of the 144 patients tested positive for the FRAXE expansion.
- The molecular techniques for detecting both FRAXA and FRAXE expansions were successfully implemented.
- The study demonstrated the practical utility of combined FRAXA and FRAXE molecular screening.
Conclusions:
- The established molecular protocol is effective for diagnosing FRAXE expansions.
- Simultaneous screening for FRAXA and FRAXE is feasible and valuable in clinical diagnostics.
- Further research may be needed to understand the prevalence of FRAXE in specific patient cohorts.