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Fragile X mental retardation and the iduronate sulphatase locus: testing laird's model of fra(X) inheritance

Clarke, Angus John ORCID:, Bradley, Don M., Gillespie, K., Rees, Dafydd Aled ORCID:, Holland, A. and Thomas, Nicholas Stuart Tudor 1992. Fragile X mental retardation and the iduronate sulphatase locus: testing laird's model of fra(X) inheritance. American Journal of Medical Genetics 43 (1-2) , pp. 299-306. 10.1002/ajmg.1320430146

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Fragile X [fra(X)] mental retardation syndrome is the most frequent familial cause of mental handicap. The clinical phenotype is associated with a rare fragile site at Xq27.3. The mutation underlying the disorder, an insertion into the FMR-1 gene, has been characterized, but the pathogenesis of the condition is obscure and the pattern of inheritance is still not fully understood. One model of fra(X) pathogenesis was proposed by Laird in 1987, suggesting that the fra(X) mutation acts as a cis-acting, local block to the pre-oogenesis reactivation of the inactivated X chromosome. To test this model, we examined the activity of the F8, F9 and iduronate sulphatase (IDS) loci. The level of IDS in the serum of fra(X) males was found to be very significantly reduced in the fra(X) group when compared to that of control males: this lends support to Laird's model of fra(X) pathogenesis. However, we detected no methylation differences between fra(X) and control samples at the IDS locus, although such changes are known in fra(X) males at sites closer to the fragile site. Thus the mechanism of the reduction in IDS activity has not been identified.

Item Type: Article
Date Type: Publication
Status: Published
Schools: Medicine
Subjects: R Medicine > R Medicine (General)
Uncontrolled Keywords: Fragile-X mental retardation; X-linked mental retardation; Martin-Bell syndrome; iduronate sulphatase.
Publisher: Wiley-Liss
ISSN: 0148-7299
Last Modified: 25 Oct 2022 09:56

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