Premature ovarian failure and FRAXA premutation: Positive correlation in a Brazilian survey.
Fragile X syndrome (FRAXA) is the most common form of inherited mental retardation (MR). The mutational mechanism leading to the disease involves an expansion of a trinucleotide repeat located at the 5' UTR region of the gene FMR-1. Four types of alleles can be identified in the population, based on the number of repeats: normal (6-40), gray-zone (41-60), premutated (61-200), and fully mutated (>200). Despite only full mutations being associated with the development of the disorder, some authors propose a correlation between FRAXA premutation and the occurrence of premature ovarian failure (POF). We have undertaken a study in 58 women from 24 fragile X syndrome families ascertained for FRAXA testing. Using Southern blotting for direct DNA analysis we have identified 19 normal, 33 premutation carriers, and 6 fully mutated individuals (including 4 somatic mosaics showing premutated and fully mutated alleles). Among the premutated women, 11 experienced menopause before the age of 40 (POF), including one somatic mosaic, which was different from the ones with normal pattern who did not experience POF. Our data corroborate the notion that females carrying alleles in the premutation range are at high risk of experiencing POF.
Machado-Ferreira
Maria do Carmo
Mdo C
Department of Cell Biology and Genetics, State University of Rio de Janeiro, Rio de Janeiro, Brazil. marlima@uerj.br
Costa-Lima
Marcelo A
MA
Boy
Raquel T
RT
Esteves
Gabriela S
GS
Pimentel
Márcia M G
MM
D000293:Adolescent; D000328:Adult; D000368:Aged; D000483:Alleles; D001938:Brazil; D002648:Child; D020090:Chromosome Segregation; D041321:Chromosomes, Human, X / Q000235:genetics*; D005260:Female; D051860:Fragile X Messenger Ribonucleoprotein 1; D005600:Fragile X Syndrome / Q000235:genetics*; D020868:Gene Silencing; D006801:Humans; D008297:Male; D008875:Middle Aged; D009419:Nerve Tissue Proteins / Q000235:genetics*; D010375:Pedigree; D016649:Primary Ovarian Insufficiency / Q000235:genetics*; D016601:RNA-Binding Proteins; D019680:Trinucleotide Repeat Expansion
D051860:Fragile X Messenger Ribonucleoprotein 1; D009419:Nerve Tissue Proteins; D016601:RNA-Binding Proteins; C497683:FMR1 protein, human