Estudo da mutação fraxa em individuos do sexo masculino com deficiencia mental de etiologia não esclarecida

AUTOR(ES)
DATA DE PUBLICAÇÃO

2004

RESUMO

mong the mental deficiencies of genetic origin the group of X-linked mental retardation (XLMR) has got special attention. lnside this group 25 to 40% corresponds to cases of ftagile X syndrome (FXS). This designation is related to the presence of a ftagile site in the Xq27.3 region, genotypically represented by FRAXA, that is caused by thevariation in the number of copies of an instable repetition of CGG trinucleotides at the 5 untranslated region ofthe FMR-l gene. The FRAXE and FRAXF sites are both located inside the region Xq27-28. The main aim of this project is to setup a reliable method to perform the molecular analysis using the PCR technique in order to screen the trinucleotides expansion mutation, and the Southem blot analysis to identify the pre- and complete mutation related to FXS in males with mental deficiency of unknown origino This group of males was chosen because there was no clinical pattem indicative of FXS and the cytogenetic analysis for such alteration was negative. The molecular analysis of the CGG repetition for a total of 54 subjects showed only one (1.9 %) individual with an expanded allele of around 7.0 kb; 51 (94.4 %) showed normal size alleles,varying between 5 and 54 CGG repetitions, and for two individuals (3.7 %) the results were inconclusive. The analysis of the normal size of the polymorphic trinucleotides repetition (CGG)n in 49 women ftom the control group showed that 65.3 % of them as eterozygotes for the normal allele,with two normal CGG alleles of different sizes. As a protocol for the diagnosis of individuais with idiopathic MO, the association of the routine cariotype examination together with PCR screening for FXS became a satisfactory tool to identifythe principal causes for MR. The implementation of the PCR and Southem blot techniques for the diagnosis of FXS represented an important step for the Molecular Genetic laboratory of the Medical Genetic Department at UNICAMP to offer one more service to the general population, keeping in mind the importance of identifying the FXS condition as a possible origin for the MO.

ASSUNTO(S)

genetica medica sindrome do cromossomo x fragil retardamento mental

ACESSO AO ARTIGO

Documentos Relacionados