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Open Access Publications from the University of California

Scholarly Works (30 results)

  • Article
  • Peer Reviewed
UC Davis Previously Published Works (2020)

Fragile X syndrome is the monogenetic condition that produces more cases of autism and intellectual disability. The repetition of CGG triplets (> 200) and their methylation entail the silencing of the FMR1 gene. The FMRP protein (product of the FMR1 gene) interacts with ribosomes by controlling the translation of specific messengers, and its loss causes alterations in synaptic connectivity. Screening for fragile X syndrome is performed by polymerase chain reaction. Current recommendation of the American Academy of Pediatrics is to test individuals with intellectual disability, global developmental retardation or with a family history of presence of the mutation or premutation. Hispanic countries such as Colombia, Chile and Spain report high prevalence of fragile X syndrome and have created fragile X national associations or corporations that seek to bring patients closer to available diagnostic and treatment networks.

    • Article
    • Peer Reviewed
    UC Davis Previously Published Works (2020)

    This review aims to assemble many years of research and clinical experience in the fields of neurodevelopment and neuroscience to present an up-to-date understanding of the clinical presentation, molecular and brain pathology associated with Fragile X syndrome, a neurodevelopmental condition that develops with the full mutation of the FMR1 gene, located in the q27.3 loci of the X chromosome, and Fragile X-associated tremor/ataxia syndrome a neurodegenerative disease experienced by aging premutation carriers of the FMR1 gene. It is important to understand that these two syndromes have a very distinct clinical and pathological presentation while sharing the same origin: the mutation of the FMR1 gene; revealing the complexity of expansion genetics.

      • Article
      • Peer Reviewed
      UC Davis Previously Published Works (2018)
      Fragile X syndrome (FXS) is caused by the full mutation (>200 CGG repeats) in the Fragile X Mental Retardation 1 (FMR1) gene. It is the most common inherited cause of intellectual disability (ID) and autism. This review focuses on neuropsychiatric disorders frequently experienced by premutation carriers with 55 to 200 CGG repeats and the pathophysiology involves elevated FMR1 mRNA levels, which is different from the absence or deficiency of fragile X mental retardation protein (FMRP) seen in FXS. Neuropsychiatric disorders are the most common problems associated with the premutation, and they affect approximately 50% of individuals with 55 to 200 CGG repeats in the FMR1 gene. Neuropsychiatric disorders in children with the premutation include anxiety, ADHD, social deficits, or autism spectrum disorders (ASD). In adults with the premutation, anxiety and depression are the most common problems, although obsessive compulsive disorder, ADHD, and substance abuse are also common. These problems are often exacerbated by chronic fatigue, chronic pain, fibromyalgia, autoimmune disorders and sleep problems, which are also associated with the premutation. Here we review the clinical studies, neuropathology and molecular underpinnings of RNA toxicity associated with the premutation. We also propose the name Fragile X-associated Neuropsychiatric Disorders (FXAND) in an effort to promote research and the use of fragile X DNA testing to enhance recognition and treatment for these disorders.
        Cover page: Fragile X-Associated Neuropsychiatric Disorders (FXAND).
        • Article
        • Peer Reviewed
        UC Davis Previously Published Works (2019)
        Fragile X Syndrome (FXS) is the most common cause of inherited intellectual disability with prevalence rates estimated to be 1:5,000 in males and 1:8,000 in females. The increase of >200 Cytosine Guanine Guanine (CGG) repeats in the 5' untranslated region of the Fragile X Mental Retardation 1 (FMR1) gene results in transcriptional silencing on the FMR1 gene with a subsequent reduction or absence of fragile X mental retardation protein (FMRP), an RNA binding protein involved in the maturation and elimination of synapses. In addition to intellectual disability, common features of FXS are behavioral problems, autism, language deficits and atypical physical features. There are still no currently approved curative therapies for FXS, and clinical management continues to focus on symptomatic treatment of comorbid behaviors and psychiatric problems. Here we discuss several treatments that target the neurobiological pathway abnormal in FXS. These medications are clinically available at present and the data suggest that these medications can be helpful for those with FXS.
          • Article
          • Peer Reviewed
          UC Davis Previously Published Works (2020)
          Fragile X syndrome (FXS) is the most common inherited cause of intellectual disability and autism spectrum disorder. In most cases, it is due to an expansion of the CGG triplet to more than 200 repeats within the promoter region of the FMR1 gene. In the premutation (PM) the trinucleotide is expanded to 55-200 repeats. PM carriers can present with disorders associated with the PM including fragile X-associated tremor/ataxia syndrome (FXTAS) and fragile X-associated ovarian insufficiency (FXPOI). Recently fragile X-associated neuropsychiatric disorders (FXAND) was proposed as an umbrella term to include the neuropsychiatric disorders that are more prevalent in PM carriers compared to the general population such as anxiety, depression, chronic fatigue, alcohol abuse, and psychosis, among others. The patient in our study was evaluated by a team of clinicians from the University del Valle in Cali who traveled to Ricaurte, a Colombian town known for being a genetic geographic cluster of FXS. A detailed medical history was collected and complete physical, neurological and psychiatric evaluations were performed in addition to molecular and neuroradiological studies. We report the case of a 78-year-old man, PM carrier, without FXTAS whose main clinical presentation consists of behavioral changes and psychosis. Brain imaging revealed white matter lesions in the periventricular region and mild cerebral atrophy. Although anxiety and depression are the most common neuropsychiatric manifestations in PM carriers, it is important to perform a complete psychiatric evaluation since some patients may present with behavioral changes and psychosis.
            Cover page: Fragile X associated neuropsychiatric disorders in a male without FXTAS
            • Article
            • Peer Reviewed
            UC Davis Previously Published Works (2019)
            Mutations in the Fragile X Mental Retardation 1 (FMR1) gene create a spectrum of developmental disorders in children in addition to neurodegenerative problems in older populations. Two types of mutations are recognized in the FMR1 gene. The full mutation (>200 CGG repeats) in the FMR1 gene leads to Fragile X Syndrome which is the most common inherited cause of intellectual disability and autism, while the premutation (55 to 200 CGG repeats) identified among carriers leads to a range of problems linked to elevated levels of the FMR1 mRNA leading to mRNA toxicity and occasionally mildly deficient FMRP levels. Two disorders among premutation carriers have been recognized namely: the Fragile X-associated Primary Ovarian Insufficiency (FXPOI) and Fragile X-associated Tremor/Ataxia Syndrome (FXTAS). Recently, in order to recognize a group of associated disorders commonly found in premutation carriers and extensively reported in co-morbidities studies, a new distinctive name was proposed: Fragile X-associated Neuropsychiatric Disorders (FXAND). This paper will present a case report of a female premutation carrier who has encountered predominantly psychiatric problems, but also chronic pain and sleep disturbances consistent with FXAND.
              Cover page: Fragile X- associated Neuropsychiatric Disorders: A Case Report.
              • Article
              • Peer Reviewed
              UC Davis Previously Published Works (2016)
              Alcohol use disorders (AUDs) have been reported in a limited number of individuals with cognitive impairment but rarely in those with fragile X syndrome (FXS). However, in Colombia, culturally, alcohol consumption is very common. Here, we report eight cases of patients with FXS who have frequent alcohol consumption in Ricaurte, Colombia. Some of these patients have also used tobacco and illegal substances, including cocaine, which use has not been previously reported in those with FXS. Alcohol and substance use dependence is associated with exacerbation of their behavioral problems, such as increased impulsivity and aggression, as well as of medical problems such as an increased frequency of seizures.
                Cover page: Alcohol use dependence in fragile X syndrome
                • Article
                • Peer Reviewed
                UC Davis Previously Published Works (2018)
                Fragile X-associated tremor/ataxia syndrome (FXTAS) affects individuals with 55-200 CGG repeats (premutation) in the 5'-untranslated region of the fragile X mental retardation 1 (FMR1) gene. FXTAS is a progressive neurodegenerative disorder associated with an action tremor, cerebellar ataxia memory and executive function deficits, autonomic dysfunction and neuropathy. Females with the fragile X premutation are often affected by fragile X-associated primary ovarian insufficiency (FXPOI), and may have other medical conditions such as fibromyalgia, depression, anxiety, and immune-mediated disorders like hypothyroidism. Here we present a case of a 54-year-old woman with tremor, ataxia, average memory skills, and executive function deficits who meets criteria for FXTAS. She also has anxiety, Major Depressive Disorder, fibromyalgia, chronic pain and was treated chronically with opioids and she overdosed on fentanyl leading to significant CNS dysfunction.
                  Cover page: Fentanyl overdose in a female with the FMR1 premutation and FXTAS.
                  • Article
                  • Peer Reviewed
                  UC Davis Previously Published Works (2018)
                  Fragile X-associated tremor/ataxia syndrome (FXTAS) affects individuals with 55-200 CGG repeats (premutation) in the 5'-untranslated region of the fragile X mental retardation 1 (FMR1) gene. FXTAS is a progressive neurodegenerative disorder associated with an action tremor, cerebellar ataxia memory and executive function deficits, autonomic dysfunction and neuropathy. Females with the fragile X premutation are often affected by fragile X-associated primary ovarian insufficiency (FXPOI), and may have other medical conditions such as fibromyalgia, depression, anxiety, and immune-mediated disorders like hypothyroidism. Here we present a case of a 54-year-old woman with tremor, ataxia, average memory skills, and executive function deficits who meets criteria for FXTAS. She also has anxiety, Major Depressive Disorder, fibromyalgia, chronic pain and was treated chronically with opioids and she overdosed on fentanyl leading to significant CNS dysfunction.
                    Cover page: Fentanyl overdose in a female with the FMR1 premutation and FXTAS.
                    • Article
                    • Peer Reviewed
                    UC Davis Previously Published Works (2020)
                    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.
                      Cover page: Fragile X-Associated Tremor/Ataxia Syndrome (FXTAS): Pathophysiology and Clinical Implications
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