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Journal of Medical Genetics logoLink to Journal of Medical Genetics
. 1993 Feb;30(2):94–96. doi: 10.1136/jmg.30.2.94

The fragile X syndrome: no evidence for any recent mutations.

A P Smits 1, J C Dreesen 1, J G Post 1, D F Smeets 1, C de Die-Smulders 1, T Spaans-van der Bijl 1, L C Govaerts 1, S T Warren 1, B A Oostra 1, B A van Oost 1
PMCID: PMC1016260  PMID: 8445628

Abstract

Fragile X (fra(X)) syndrome, the most common form of familial mental retardation, is caused by heritable unstable DNA composed of CGG repeats. As reproductive fitness of fra(X) patients is severely compromised, a high mutation rate has been proposed to explain the high prevalence. However, we have been unable to show any new mutation for 84 probands referred to us to date. We show here the same fra(X) gene in five fra(X) probands with common ancestors married in 1747. The lack of new fra(X) mutations implies that there must be many more fra(X) gene carriers in the population than previously realised. As it is now possible to detect asymptomatic fra(X) gene carriers by DNA analysis, extended family studies for any new proband are recommended. A family illustrating the importance of fra(X) carriership determination is reported.

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Selected References

These references are in PubMed. This may not be the complete list of references from this article.

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