Fragile X syndrome is associated with a trinucleotide (CGG) repeat expansion in the 5'-untranslated region of the FMR1 gene and hypermethylation of the FMR1 promoter. Rare cases of clinically normal males (HFM) have been identified with an expanded CGG repeat; however, here, the FMR1 promoter is not methylated. Using classical complementation (cell fusion) studies, we analyzed if possible diffe...

CGG repeat expansions in the Fragile X mental retardation 1 (FMR1) gene are responsible for a family of associated disorders characterized by either intellectual disability and autism Fragile X Syndrome (FXS), or adult-onset neurodegeneration Fragile X-associated Tremor/Ataxia Syndrome. However, the FMR1 locus is complex and encodes several long non-coding RNAs, whose expression is altered by r...

The main mutation responsible for the fragile X syndrome is the expansion of an untranslated CGG repeat in the first exon of the FMR1 gene, associated with the hypermethylation of the proximal CpG island and the CGG repeat region, and repression of transcription of FMR1. Fragile X syndrome mosaicism has been described as the coexistence of the full mutation and the permutation. We present here ...

Fragile X syndrome is caused by the absence of the mRNA-binding protein Fragile X mental retardation protein (FMRP), which may play a role in activity-regulated localization and translation of mRNA in dendrites and at synapses. We investigated whether neuronal activity and glutamatergic signals regulate trafficking of FMRP and its encoding Fmr1 mRNA into dendrites or at synapses. Using high-res...

Fragile X syndrome, diagnosed by Fragile X Mental Retardation 1 (FMR1) DNA testing, is the most common single-gene cause of inherited intellectual disability. The expanded CGG mutation in the FMR1 gene, once thought to have clinical significance limited to fragile X syndrome, is now well established as the cause for other fragile X-associated disorders including fragile X-associated primary ova...

Fragile X syndrome, the most frequent form of hereditary mental retardation, is due to a mutation of the fragile X mental retardation 1 (FMR1) gene on the X chromosome. Like fragile X patients, FMR1-knockout (FMR1-KO) mice lack the normal fragile X mental retardation protein (FMRP) and show both cognitive alterations and an immature neuronal morphology. We reared FMR1-KO mice in a C57BL/6 backg...

Fragile X syndrome is a common inherited form of mental impairment. Fragile X mental retardation protein (FMRP) plays important roles in the regulation of synaptic protein synthesis, and loss of FMRP leads to deficits in learning-related synaptic plasticity and behavioral disability. Previous studies mostly focus on postsynaptic long-term potentiation (LTP) in Fmr1 knock-out (KO) mice. Here, we...

Despite the critical importance of voltage-gated ion channels in neurons, very little is known about their functional properties in Fragile X syndrome: the most common form of inherited cognitive impairment. Using three complementary approaches, we investigated the physiological role of A-type K(+) currents (I(KA)) in hippocampal CA1 pyramidal neurons from fmr1-/y mice. Direct measurement of I(...

BACKGROUND Increased expression of the Fragile X Mental Retardation 1 (FMR1) gene in blood cells has been claimed to be associated with variable (CGG)(n) triplet numbers in the 5' untranslated region of this gene. Increased CGG triplet numbers, including that of the so-called premutation range (n= 55-200), were shown to have a risk of <26% to impair ovarian reserve leading to primary ovarian in...

Fragile X syndrome (FXS) is caused by a failure of neuronal cells to express the gene encoding the fragile mental retardation protein (FMRP). Clinical features of the syndrome include intellectual disability, learning impairment, hyperactivity, seizures and anxiety. Fmr1 knockout (KO) mice do not express FMRP and, as a result, reproduce some FXS behavioral abnormalities. While intrinsic and syn...