Structure and stability upon maternal transmission of common and intermediate FMR1 (Fragile X Mental Retardation 1) alleles in a sample of the Brazilian population
AUTOR(ES)
Capelli, Leonardo P., Mingroni-Netto, Regina C., Vianna-Morgante, Angela M.
FONTE
Genetics and Molecular Biology
DATA DE PUBLICAÇÃO
2005-03
RESUMO
In order to investigate the stability of the FMR1 (Fragile X Mental Retardation 1) alleles from the normal population, when maternally inherited, we analyzed 75 mother-to-son transmissions. Sixty-eight alleles fell within the common range with 20-40 CGG repeats, and seven alleles were intermediate, with 41-48 repeats. No change was observed either in the length or in the structure of these repeats upon transmission. Fifty-three alleles were ascertained in different families, and their size distribution was similar to those described for European and European-derived populations, with three peaks of frequency: 66% of the alleles with (CGG)29, (CGG)30 or (CGG)31, 7.5% with (CGG)20, and 5.7% with (CGG)23. Regarding the AGG interspersion pattern, 69.8% had two AGG repeats, 20.8% had one, 5.7% had three and 3.8% had none. The most common patterns were 10+9+9 (30.2%), 9+9+9 (18.9%), 10+9 (7.5%), and 10+9+10 (7.5%). About 70% of the alleles with up to 40 repeats were linked to the DXS548/FRAXAC1 haplotype 7-3, the most commonly reported in normal populations. Four out of five intermediate alleles were in linkage with the two haplotypes most frequently associated to the FMR1 full mutation, 2-1 and 6-4. These four alleles showed long uninterrupted CGG repeats at the 3' end. The 9+9+22, 9+9+23 and 9+9+28 alleles were linked to the haplotype 2-1, and the 9+37 allele, to the haplotype 6-4. The pattern of AGG interspersion of these alleles and the associated haplotypes were in accordance with the two main pathways toward mutation previously proposed.
Documentos Relacionados
- X inactivation of the FMR1 fragile X mental retardation gene.
- Population genetics of the fragile-X syndrome: multiallelic model for the FMR1 locus.
- Paternally Transmitted FMR1 Alleles Are Less Stable than Maternally Transmitted Alleles in the Common and Intermediate Size Range
- Characterization of dFMR1, a Drosophila melanogaster Homolog of the Fragile X Mental Retardation Protein
- Frontostriatal deficits in fragile X syndrome: Relation to FMR1 gene expression