In individuals with the fragile X syndrome (FRAXA), the methylation boundary is lost; methylation has penetrated into the FMR1 promoter and inactivated the FMR1 gene.
In the present behavioral study, long-term effects of deficiency of FMRP were investigated by examining the acquisition, savings and extinction of delay eyeblink conditioning in male individuals with FRAXA.
Fragile X mental retardation protein shifts between polyribosomes and stress granules after neuronal injury by arsenite stress or in vivo hippocampal electrode insertion.
Metabotropic glutamate receptor activation regulates fragile x mental retardation protein and FMR1 mRNA localization differentially in dendrites and at synapses.
Fragile X syndrome (FRAXA) is characterized at the molecular level by an expansion of a naturally occurring 5'-(CGG)(n)-3' repeat in the promoter and 5'-untranslated region (5'-UTR) of the fragile X mental retardation (FMR1) gene on human chromosome Xq27.3.
The gene responsible for the FRAXA syndrome, the FMR1 gene, has been cloned. inactivation of the FMR1 gene is associated with amplification of a trinucle-otide CGG repeat sequence and methylation of an adjacent CpG island.
This technique was successfully established into our laboratory routine showing the practical use of testing for FRAXA and FRAXE in a large series of patients.
To date four types of trinucleotide repeat expansions have been identified: (1) long cytosine-guanine-guanine (CGG) repeats in the two fragile X syndromes (FRAXA and FRAXE), (2) long cytosine-thymine-guanine (CTG) repeat expansions in myotonic dystrophy, (3) long guanine-adenine-adenine repeat expansions in Friedreich's ataxia and (4) short cytosine-adenine-guanine repeat expansions (CAG) which are implicated in eight neurodegenerative disorders and are the focus of this review.
The fragile X syndrome (FRAXA) is the most widespread heritable form of mental retardation caused by the lack of expression of the fragile X mental retardation protein (FMRP).
To date four types of trinucleotide repeat expansions have been identified: (1) long cytosine-guanine-guanine (CGG) repeats in the two fragile X syndromes (FRAXA and FRAXE), (2) long cytosine-thymine-guanine (CTG) repeat expansions in myotonic dystrophy, (3) long guanine-adenine-adenine repeat expansions in Friedreich's ataxia and (4) short cytosine-adenine-guanine repeat expansions (CAG) which are implicated in eight neurodegenerative disorders and are the focus of this review.