The fragile X-associated tremor/ataxia syndrome (FXTAS) is a neurodegenerative disorder seen in older premutation (55–200 CGG repeats) carriers of FMR1. The premutation has excessive levels of FMR1 mRNA that lead to toxicity and mitochondrial dysfunction. The clinical features usually begin in the 60 s with an action or intention tremor followed by cerebellar ataxia, although 20% have only ataxia. MRI features include brain atrophy and white matter disease, especially in the middle cerebellar peduncles, periventricular areas, and splenium of the corpus callosum. Neurocognitive problems include memory and executive function deficits, although 50% of males can develop dementia. Females can be less affected by FXTAS because of a second X chromosome that does not carry the premutation. Approximately 40% of males and 16% of female carriers develop FXTAS. Since the premutation can occur in less than 1 in 200 women and 1 in 400 men, the FXTAS diagnosis should be considered in patients that present with tremor, ataxia, parkinsonian symptoms, neuropathy, and psychiatric problems. If a family history of a fragile X mutation is known, then FMR1 DNA testing is essential in patients with these symptoms.

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There is a dearth of information about cardiovascular problems in fragile X premutation carriers who have 55–200 CGG repeats in fragile X mental retardation 1 ( FMR1 ) gene. The FMR1 expansion in the premutation range leads to toxic RNA gain-of-function resulting in cellular dysregulation. The mechanism of RNA toxicity underlies all of the premutation disorders including fragile X-associated tremor/ataxia syndrome, fragile X-associated primary ovarian insufficiency, and fragile X-associated neuropsychiatric disorder. Cardiovascular problems particularly autonomic dysfunction, hypertension, and cardiac arrhythmias are not uncommon in premutation carriers. Some arterial problems and valvular heart diseases have also been reported. This article reviews cardiovascular problems in premutation carriers and discusses possible contributing mechanisms including RNA toxicity and mild fragile X mental retardation protein deficiency. Further research studies are needed in order to prove a direct association of the cardiovascular problems in fragile X premutation carriers because such knowledge will lead to better preventative treatment.

BackgroundWhile an association between full mutation CGG-repeat expansions of the Fragile X Mental Retardation 1 (FMR1) gene and connective tissue problems are clearly described, problems in fragile X premutation carriers (fXPCs) CGG-repeat range (55–200 repeats) of the FMR1 gene may be overlooked.ObjectiveTo report five FMR1 fXPCs cases with the hypermobile Ehlers-Danlos syndrome (hEDS) phenotype.MethodsWe collected medical histories and FMR1 molecular measures from five cases who presented with joint hypermobility and loose connective tissue and met inclusion criteria for hEDS.ResultsFive cases were female and ranged between 16 and 49 years. The range of CGG-repeat allele sizes ranged from 66 to 150 repeats. All had symptoms of hEDS since early childhood. Commonalities in molecular pathogenesis and coexisting conditions between the fXPCs and hEDS are also presented. The premutation can lead to a reduction of fragile X mental retardation protein, which is crucial in maintaining functions of the extracellular matrix-related proteins, particularly matrix metallopeptidase 9 and elastin. Moreover, elevated FMR1 messenger RNA causes sequestration of proteins, which results in RNA toxicity.ConclusionBoth hEDS phenotype and premutation involvement may co-occur because of related commonalities in pathogenesis.

Fragile X-associated tremor and ataxia syndrome (FXTAS) is a neurodegenerative disease developed by carriers of a premutation in the fragile X mental retardation 1 (FMR1) gene. The core clinical symptoms usually manifest in the early 60s, typically beginning with intention tremor followed by cerebellar ataxia. Ataxia can be the only symptom in approximately 20% of the patients. FXTAS has a slow progression, and patients usually experience advanced deterioration 15 to 25 years after the initial diagnosis. Common findings in brain imaging include substantial brain atrophy and white matter disease (WMD). We report three cases with an atypical clinical presentation, all presenting with gait problems as their initial manifestation and with ataxia as the dominant symptom without significant tremor, as well as a faster than usual clinical progression. Magnetic resonance imaging (MRI) was remarkable for severe brain atrophy, ventriculomegaly, thinning of the corpus callosum, and periventricular WMD. Two cases were diagnosed with definite FXTAS on the basis of clinical and radiological findings, with one individual also developing moderate dementia. Factors such as environmental exposure and general anesthesia could have contributed to their clinical deterioration. FXTAS should be considered in the differential diagnosis of patients presenting with ataxia, even in the absence of tremor, and FMR1 DNA testing should be sought in those with a family history of fragile X syndrome or premutation disorders.

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Fragile X syndrome (FXS) is the most common single gene disorder, which causes autism and intellectual disability. The fragile X mental retardation 1 (FMR1) gene is silenced when cytosine-guanine-guanine (CGG) triplet repeats exceed 200, which is the full mutation that causes FXS. Carriers of FXS have a CGG repeat between 55 and 200, which is defined as a premutation and transcription of the gene is overactive with high levels of the FMR1 mRNA. Most carriers of the premutation have normal levels of fragile X mental retardation protein (FMRP) and a normal intelligence, but in the upper range of the premutation (120-200) the FMRP level may be lower than normal. The clinical problems associated with the premutation are caused by the RNA toxicity associated with increased FMR1 mRNA levels, although for some mildly lowered FMRP can cause problems associated with FXS. The RNA toxicity causes various health problems in the carriers including but not limited to fragile X-associated tremor/ataxia syndrome, fragile X-associated primary ovarian insufficiency, and fragile X-associated neuropsychiatric disorders. Since some individuals with neuropsychiatric problems do not meet the severity for a diagnosis of a "disorder" then the condition can be labeled as fragile X premutation associated condition (FXPAC). Physicians must be able to recognize these health problems in the carriers and provide appropriate management.FMR1, fragile X premutation associated conditions, fragile X-associated neuropsychiatric disorders, fragile X-associated primary ovarian insufficiency, fragile X-associated tremor/ ataxia syndrome, premutation | INTRODUCTIONFragile X syndrome (FXS) is caused by mutations of the fragile X mental retardation 1 (FMR1) gene at Xq27.3. Almost all of the mutations (> 99%) are due to more than 200+ repeats of cytosine-guanine-guanine (CGG) in the FMR1 gene, which is called "full mutation." The CGG expansion leads to methylation at the promoter region of the FMR1 gene and transcriptional silencing which result in fragile X mental retardation protein (FMRP) deficiency. FMRP, which is abundant in neurons, is a regulatory protein in synaptogenesis. 1 The hallmarks of FXS are developmental delay, intellectual disability, and autism spectrum disorder (ASD). Elongated face, prominent and large ears, macrocephaly, and macroorchidism beginning at the pubertal period are also characteristic of FXS. A systematic review and meta-analysis reported that the prevalence of FXS is approximately 1:7143 in males and 1:11 111 in females. 2 In 1-2% of individuals with ASD, FXS was identified. 3 However, FXS is still underrecognized and the availability of fragile X DNA testing is limited, and thus the prevalence may be underestimated.Whenever FXS is diagnosed, fragile X premutation carriers should be sought in the proband's family. The premutation range is 55-200 CGG repeats in the FMR1 gene. In a systematic review and meta-analysis, premutation was detected at a rate of 1:855 in males and 1:291 in females, rates, which were more prevalent ...

Many targeted treatment studies have been carried out in individuals with Fragile X Syndrome (FXS) guided by animal studies from the Fragile X Mental Retardation 1 (FMR1) knock out (KO) mice and the fragile X Drosophila studies. Here we review the many medications that have been studied in patients with FXS and some of these medications are available for clinical use by wise clinicians. Other medications are not currently available by prescription because they are not approved by the FDA. No medication has received specific approval for treatment of FXS, although some have shown benefit from clinical studies. There is much to be done in the treatment of those with FXS and this report describes those pharmacological treatments that target the neurobiological mechanisms that are dysregulated by the lack of the Fragile X Protein (FMRP) in those with FXS.