Molecular diagnosis of the fragile X and FRAXE syndromes in patients with mental retardation of unknown cause in Mexico
Por:
González-Del Angel A., Vidal S., Saldaña Y., Del Castillo V., Angel Alcántara M., MacÍas M., Pedro Luna J., Orozco L.
Publicada:
1 ene 2000
Resumen:
The fragile X syndrome (Fra-X) is the most common cause of inherited mental retardation with X-linked semi-dominant inheritance. The prevalence of Fra-X in the Mexican population is unknown. The aim of this population screening study was to determine if Fra-X or FRAXE mutations are the cause of a number of cases of mental retardation in a sample of Mexican children with mental retardation of unknown cause (MRUC) and to stress the importance of performing molecular analysis of the FMR-1 gene in all patients with MRUC. We report here the direct analysis of CGG and GCC repeats within the FMR-1 and FMR-2 genes, respectively, in 62 unrelated patients with MRUC. Two male index cases had the CGG expansion, although they did not express the Xq27.3 fragile site cytogenetically. Fra-X diagnosis was highly suspected on a clinical basis in one of the patients, but not in the other. Both mothers were found to be premutation carriers. The molecular studies of FMR-1 showed that the proportion of MRUC patients with Fra-X is 3.2%. This frequency was not significantly different to that reported in most populations. As reported in other series, no patients with FRAXE were found in our sample. Our findings confirm that the molecular analysis of the FMR-1 gene is necessary in MRUC patients to achieve unequivocal diagnosis of fragile X syndrome, carrier premutation detection and for accurate genetic counseling. (C) 2000 Editions scientifiques et medicales Elsevier SAS.
Filiaciones:
González-Del Angel A.:
Molecular Biology Laboratory, Dept. Res. Hum. Genet., Natl. I., Mexico City, Mexico
Molecular Biomedicine Department, CINVESTAV-IPN, Mexico City, Mexico
Vidal S.:
Molecular Biology Laboratory, Dept. Res. Hum. Genet., Natl. I., Mexico City, Mexico
Saldaña Y.:
Molecular Biology Laboratory, Dept. Res. Hum. Genet., Natl. I., Mexico City, Mexico
Interinstitutional Prog. Molec. B., CICATA-IPN, Mexico City, Mexico
Del Castillo V.:
Molecular Biology Laboratory, Dept. Res. Hum. Genet., Natl. I., Mexico City, Mexico
Angel Alcántara M.:
Molecular Biology Laboratory, Dept. Res. Hum. Genet., Natl. I., Mexico City, Mexico
MacÍas M.:
Molecular Biology Laboratory, Dept. Res. Hum. Genet., Natl. I., Mexico City, Mexico
Pedro Luna J.:
Molecular Biomedicine Department, CINVESTAV-IPN, Mexico City, Mexico
Interinstitutional Prog. Molec. B., CICATA-IPN, Mexico City, Mexico
Orozco L.:
Molecular Biology Laboratory, Dept. Res. Hum. Genet., Natl. I., Mexico City, Mexico
Interinstitutional Prog. Molec. B., CICATA-IPN, Mexico City, Mexico
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