Fragile X syndrome is the most common inherited form of mental retardation. Although this syndrome originates from the absence of the RNA-binding protein FMRP, the molecular mechanisms underlying the cognitive deficits are unknown. The expression pattern of 6789 genes was studied in the brains of wild-type and FMR1 knockout mice, a fragile X syndrome animal model that has been associated with c...

Carriers of premutation alleles (55-200 CGG repeats) of the fragile-X mental retardation 1 (FMR1) gene are often regarded as being clinically uninvolved. However, it is now apparent that such individuals can present with one (or more) of three distinct clinical disorders: mild cognitive and/or behavioral deficits on the fragile-X spectrum; premature ovarian failure; and a newly described, neuro...

F ragile X syndrome (MIM No 3009550) is the most common inherited mental retardation disorder, affecting approximately 1 in 4000 males and 1 in 8000 females. Its name was derived from the observation of a fragile site on chromosome Xq27.3, designated FRAXA (fragile site, X chromosome, A site). This syndrome is caused by mutations in the fragile X mental retardation-1 gene (FMR1), more than 95% ...

CONTEXT Fragile X premutation conditions are associated with a significant degree of psychopathology and thus are of interest to the psychiatrist. Remarkable advances at the molecular level have enhanced our understanding of fragile X premutation disorders. OBJECTIVE The authors review the genetic, molecular, neuroimaging, and clinical (systemic, neurologic, and psychiatric) manifestations of...

Screening for fragile X premutations is recommended for the routine work-up for any woman presenting with premature ovarian failure (POF). The reason for this is that women with POF have an approximate 5% chance of conceiving and this possibility may be increased further in the FRAXA premutation subgroup. Women need to be informed if they are at risk of having a child with fragile X syndrome. I...

Patient Selection Criteria Coverage eligibility will be considered for fragile X mental retardation 1 (FMR1) mutations the following patient populations:  Individuals of either sex with intellectual disability, developmental delay, or autism spectrum disorder (see Policy Guidelines ◊ ).  Prenatal testing of fetuses of known carrier mothers (see Policy Guidelines ◊ ).  Affected individuals or...

Trace fear memory requires the activity of the anterior cingulate cortex (ACC) and is sensitive to attention-distracting stimuli. Fragile X syndrome is the most common form of mental retardation with many patients exhibiting attention deficits. Previous studies in fragile X mental retardation 1 (FMR1) knock-out (KO) mice, a mouse model for fragile X, focused mainly on hippocampal-dependent plas...

Fragile X syndrome (FXS) and its associated disorders are caused by the expansion of the CGG repeat in the 5' untranslated region of the fragile X mental retardation 1 gene (FMR1). The full mutation, defined as >200 cytosine-guanine-guanine (CGG) triplet repeats, causes FXS. Individuals with 55-199 CGG repeats, classified as premutation carriers, are affected by two distinct disorders depending...