Elevated FMR1-mRNA and lowered FMRP - A double-hit mechanism for psychiatric features in men with FMR1 premutations.

Fragile X syndrome (FXS) is caused by a full mutation of the FMR1 gene (>200 CGG repeats and subsequent methylation), such that there is little or no FMR1 protein (FMRP) produced, leading to intellectual disability (ID). Individuals with the premutation allele (55-200 CGG repeats, generally unmethylated) have elevated FMR1 mRNA levels, a consequence of enhanced transcription, resulting in neuronal toxicity and a spectrum of premutation-associated disorders, including the neurodegenerative disorder fragile X-associated tremor/ataxia syndrome (FXTAS). Here we described 14 patients who had both lowered FMRP and elevated FMR1 mRNA levels, representing dual mechanisms of clinical involvement, which may combine features of both FXS and FXTAS. In addition, the majority of these cases show psychiatric symptoms, including bipolar disorder, and/or psychotic features, which are rarely seen in those with just FXS.

Fragile X Newborn Screening: Lessons Learned From a Multisite Screening Study.

BACKGROUND: Delays in the diagnosis of children with fragile X syndrome (FXS) suggest the possibility of newborn screening as a way to identify children earlier. However, FXS does not have a proven treatment that must be provided early, and ethical concerns have been raised about the detection of infants who are carriers. This article summarizes major findings from a multisite, prospective, longitudinal pilot screening study. METHODS: Investigators in North Carolina, California, and Illinois collaborated on a study in which voluntary screening for FXS was offered to parents in 3 birthing hospitals. FXS newborn screening was offered to >28 000 families to assess public acceptance and determine whether identification of babies resulted in any measurable harms or adverse events. Secondary goals were to determine the prevalence of FMR1 carrier gene expansions, study the consent process, and describe early development and behavior of identified children. RESULTS: A number of publications have resulted from the project. This article summarizes 10 "lessons learned" about the consent process, reasons for accepting and declining screening, development and evaluation of a decision aid, prevalence of carriers, father participation in consent, family follow-up, and maternal reactions to screening. CONCLUSIONS: The project documented public acceptance of screening as well as the challenges inherent in obtaining consent in the hospital shortly after birth. Collectively, the study provides answers to a number of questions that now set the stage for a next generation of research to determine the benefits of earlier identification for children and families.

Premutation in the Fragile X Mental Retardation 1 (FMR1) Gene Affects Maternal Zn-milk and Perinatal Brain Bioenergetics and Scaffolding.

Fragile X premutation alleles have 55-200 CGG repeats in the 5' UTR of the FMR1 gene. Altered zinc (Zn) homeostasis has been reported in fibroblasts from >60 years old premutation carriers, in which Zn supplementation significantly restored Zn-dependent mitochondrial protein import/processing and function. Given that mitochondria play a critical role in synaptic transmission, brain function, and cognition, we tested FMRP protein expression, brain bioenergetics, and expression of the Zn-dependent synaptic scaffolding protein SH3 and multiple ankyrin repeat domains 3 (Shank3) in a knock-in (KI) premutation mouse model with 180 CGG repeats. Mitochondrial outcomes correlated with FMRP protein expression (but not FMR1 gene expression) in KI mice and human fibroblasts from carriers of the pre- and full-mutation. Significant deficits in brain bioenergetics, Zn levels, and Shank3 protein expression were observed in the Zn-rich regions KI hippocampus and cerebellum at PND21, with some of these effects lasting into adulthood (PND210). A strong genotype × age interaction was observed for most of the outcomes tested in hippocampus and cerebellum, whereas in cortex, age played a major role. Given that the most significant effects were observed at the end of the lactation period, we hypothesized that KI milk might have a role at compounding the deleterious effects on the FMR1 genetic background. A higher gene expression of ZnT4 and ZnT6, Zn transporters abundant in brain and lactating mammary glands, was observed in the latter tissue of KI dams. A cross-fostering experiment allowed improving cortex bioenergetics in KI pups nursing on WT milk. Conversely, WT pups nursing on KI milk showed deficits in hippocampus and cerebellum bioenergetics. A highly significant milk type × genotype interaction was observed for all three-brain regions, being cortex the most influenced. Finally, lower milk-Zn levels were recorded in milk from lactating women carrying the premutation as well as other Zn-related outcomes (Zn-dependent alkaline phosphatase activity and lactose biosynthesis-whose limiting step is the Zn-dependent ß-1,4-galactosyltransferase). In premutation carriers, altered Zn homeostasis, brain bioenergetics and Shank3 levels could be compounded by Zn-deficient milk, increasing the risk of developing emotional and neurological/cognitive problems and/or FXTAS later in life.

Identification of a male with fragile X syndrome through newborn screening.

A pilot newborn screening (NBS) study for fragile X syndrome was recently conducted at the University of California, Davis Medical Center. The screening study identified a case of a male with the full mutation completely methylated and no detectable expression of the fragile X mental retardation-1 (FMR1) gene. The patient was initially seen in clinic at the MIND Institute, for medical follow-up and a genetic counseling session at the chronological age of 3 months. Since then, he has been seen in clinic every six months for follow up, medical examination and developmental assessments. Longitudinally administered developmental testing of the infant has revealed persistent delays in development, consistent with fragile X syndrome. Cascade testing revealed that the patient's mother and two siblings also have the full mutation. The patient has been receiving speech and language therapy, combined with physical and occupational therapies on a weekly basis since the age of one year. He is currently being treated with 2.5 mg of sertraline, which has been demonstrated to be helpful for improving language in young children with the syndrome.

Maternal Consequences of the Detection of Fragile X Carriers in Newborn Screening.

OBJECTIVES: The possibility of newborn screening for fragile X syndrome is complicated by the potential for identifying premutation carriers. Although knowing the child's carrier status has potential benefits, the possibility of late-onset disorders in carrier children and their parents raises concerns about whether such information would be distressing to parents and potentially more harmful than helpful. This study sought to answer this question by offering voluntary fragile X screening to new parents and returning results for both the full mutation and premutation FMR1 gene expansions. We tested the assumption that such information could lead to adverse mental health outcomes or decision regret. We also wanted to know if child age and spousal support were associated with the outcomes of interest. METHODS: Eighteen mothers of screen-positive infants with the premutation and 15 comparison mothers completed a battery of assessments of maternal anxiety, postpartum depression, stress, family quality of life, decision regret, and spousal support. The study was longitudinal, with an average of 3 assessments per mother. RESULTS: The premutation group was not statistically different from the comparison group on measures of anxiety, depression, stress, or quality of life. A subset of mothers experienced clinically significant anxiety and decision regret, but factors associated with these outcomes could not be identified. Greater spousal support was generally associated with more positive outcomes. CONCLUSIONS: Although we did not find evidence of significant adverse events, disclosure of newborn carrier status remains an important consideration in newborn screening policy.

High functioning male with fragile X syndrome and fragile X-associated tremor/ataxia syndrome.

Fragile X syndrome (FXS) affects individuals with more than 200 CGG repeats (full mutation) in the fragile X mental retardation 1 (FMR1) gene. Those born with FXS experience cognitive and social impairments, developmental delays, and some features of autism spectrum disorders. Carriers of a premutation (55-200 CGG repeats) are generally not severely affected early in life; however, are at high risk of developing the late onset neurodegenerative disorder, Fragile X-associated Tremor/Ataxia Syndrome (FXTAS), or Fragile X-associated Primary Ovarian Insufficiency (FXPOI), and may have other medical conditions such as developmental delay, autism spectrum disorders, hypertension, anxiety, and immune-mediated disorders. Here we present a case of a 58-year-old man with a borderline IQ, average memory skills, and executive function deficits. He met criteria for multiple psychiatric diagnoses and presented with tremor and ataxia, meeting criteria for FXTAS. Molecular testing unveiled a completely unmethylated FMR1 full mutation in peripheral blood mononucleated cells with elevated FMR1 mRNA and premutation alleles of different sizes in two other tissues (primary fibroblasts and sperm), indicating the presence of allele instability based on both inter- and intra-tissue mosaicism. The observation of FXTAS in this case of a full mutation mosaic man suggests that the pathogenic mechanism underlying this disorder is not observed exclusively in premutation carriers as it was originally thought. The concomitant presence of features of FXS and late onset neurological deterioration with probable FXTAS likely result from a combined molecular pathology of elevated FMR1 mRNA levels, a molecular hallmark of FXTAS and low FMRP expression that leads to FXS.

Newborn screening and cascade testing for FMR1 mutations.

We describe an ongoing pilot project in which newborn screening (NBS) for FMR1 mutations and subsequent cascade testing are performed by the MIND Institute at the University of California, Davis Medical Center (UCDMC). To date, out of 3,042 newborns initially screened, 44 extended family members have been screened by cascade testing of extended family members once a newborn is identified. Fourteen newborns (7 males and 7 females) and 27 extended family members (5 males and 22 females) have been identified with FMR1 mutations. Three family histories are discussed in detail, each demonstrating some benefits and risks of NBS and cascade testing for FMR1 mutations in extended family members. While we acknowledge inherent risks, we propose that with genetic counseling, clinical follow-up of identified individuals and cascade testing, NBS has significant benefits. Treatment for individuals in the extended family who would otherwise not have received treatment can be beneficial. In addition, knowledge of carrier status can lead to lifestyle changes and prophylactic interventions that are likely to reduce the risk of late onset neurological or psychiatric problems in carriers. Also with identification of carrier family members through NBS, reproductive choices become available to those who would not have known that they were at risk to have offspring with fragile X syndrome.

FMR1 CGG allele size and prevalence ascertained through newborn screening in the United States.

BACKGROUND: Population screening for FMR1 mutations has been a topic of considerable discussion since the FMR1 gene was identified in 1991. Advances in understanding the molecular basis of fragile X syndrome (FXS) and in genetic testing methods have led to new, less expensive methodology to use for large screening endeavors. A core criterion for newborn screening is an accurate understanding of the public health burden of a disease, considering both disease severity and prevalence rate. This article addresses this need by reporting prevalence rates observed in a pilot newborn screening study for FXS in the US. METHODS: Blood spot screening of 14,207 newborns (7,312 males and 6,895 females) was conducted in three birthing hospitals across the United States beginning in November 2008, using a PCR-based approach. RESULTS: The prevalence of gray zone alleles was 1:66 females and 1:112 males, while the prevalence of a premutation was 1:209 females and 1:430 males. Differences in prevalence rates were observed among the various ethnic groups; specifically higher frequency for gray zone alleles in males was observed in the White group compared to the Hispanic and African-American groups. One full mutation male was identified (>200 CGG repeats). CONCLUSIONS: The presented pilot study shows that newborn screening in fragile X is technically feasible and provides overall prevalence of the premutation and gray zone alleles in the USA, suggesting that the prevalence of the premutation, particularly in males, is higher than has been previously reported.

AGG interruptions within the maternal FMR1 gene reduce the risk of offspring with fragile X syndrome.

PURPOSE: The ability to accurately predict the likelihood of expansion of the CGG repeats in the FMR1 gene to a full mutation is of critical importance for genetic counseling of women who are carriers of premutation alleles (55-200 CGG repeats) and who are weighing the risk of having a child with fragile X syndrome. The presence of AGG interruptions within the CGG repeat tract is thought to decrease the likelihood of expansion to a full mutation during transmission, thereby reducing risk, although their contribution has not been quantified. METHODS: We retrospectively analyzed 267 premutation alleles for number and position of AGG interruptions, length of pure CGG repeats, and CGG repeat lengths present in the offspring of the maternal transmissions. In addition, we determined the haplotypes of four markers flanking the 5'-UTR locus in the premutation mothers. RESULTS: We found that the presence of AGG interruptions significantly increased genetic stability, whereas specific haplotypes had a marginal association with transmission instability. CONCLUSION: The presence of AGG interruptions reduced the risk of transmission of a full mutation for all maternal (premutation) repeat lengths below ~100 CGG repeats, with a differential risk (0 vs. 2 AGG) exceeding 60% for alleles in the 70- to 80-CGG repeat range.

Clinical phenotypes of a juvenile sibling pair carrying the fragile X premutation.

Individuals with alleles containing 55-200 CGG repeats in the fragile X mental retardation (FMR1) gene are premutation carriers. The premutation allele has been shown to lead to a number of types of clinical involvement, including shyness, anxiety, social deficits, attention deficit hyperactivity disorder (ADHD), and executive function deficits. Some of these problems could be due to mild deficits of the fragile X protein (FMRP) and a possible developmental effect of the elevated FMR1 mRNA observed in carriers. In addition, two abnormal phenotypes specific to the premutation have been described. Primary ovarian insufficiency (FXPOI), defined by cessation of menses prior to age 40, occurs in 20% of females with the premutation. The other phenotype, fragile X-associated tremor/ataxia syndrome (FXTAS), affects some older adult premutation carriers. Premutation females typically have one expanded allele (≥55 CGG repeats) and one normal allele (≤54 CGG repeats). This study describes the cognitive, behavioral, and molecular profile of a female with two alleles in the premutation range (60 and 67 CGG repeats) in comparison to her brother with a similar premutation size (65 CGG repeats). Both exhibited high IQ scores, anxiety, and some physical features associated with fragile X syndrome. This comparison allows us to examine the effect of the premutation in this male-female pair while controlling for environmental and background genetic factors.

Assessment of patient and caregiver needs in fragile X-associated tremor/ataxia syndrome by utilizing Q-sort methodology.

OBJECTIVES: Psychosocial stressors faced by patients with fragile X-associated tremor/ataxia syndrome (FXTAS) and their caregivers have not been systematically explored. FXTAS is a neurodegenerative disease occurring in approximately 45% of elderly male carriers and 8-16% of female carriers of the fragile X mental retardation one premutation. This study investigated the subjective needs of patients with FXTAS and their family caregivers, by utilizing Q-sort methodology. METHOD: Patients with FXTAS and their caregivers seen during January 2005 to June 2007 participated. The Q-sort was composed of 17 (eight formal and nine informal) items, designed to explore emotional, informational, and instrumental needs of patients with FXTAS and their caregivers. Item scores were generated from 1 = least important to 7 = most important. Analysis included descriptive statistics for all the demographic and outcome variables. Generalized estimating equations were used to identify which of the need domains were perceived as most important by the participants. RESULTS: A total of 24 patients (79% men, mean age 65.6 ± 6.4 years) with FXTAS and 18 caregivers (11% men, mean age 63.6 ± 6.2 years) completed the Q-sort. Both patients and caregivers rated informational needs as most important, followed by emotional and, finally, by instrumental needs. Participants lacked many important resources, in particular those addressing instrumental needs. CONCLUSION: Providers should be educated and able to provide timely information and referrals to formal services, as well as to informal resources, including the National Fragile X Foundation online support network (www.fragilex.org).

Aging in fragile X syndrome.

Many studies have focused on the behavior and cognitive problems in young patients with fragile X syndrome (FXS), but there are no studies about the problems in aging for those with FXS. The discovery of the fragile X-associated tremor ataxia syndrome (FXTAS), a neurodegenerative disorder related to elevated FMR1-mRNA, in elderly men and some women with the premutation, intensified the need for aging studies in FXS. Approximately 40% of males with FXS have repeat size mosaicism and as a result, some of these individuals also have elevated levels of FMR1-mRNA which theoretically puts them at risk for FXTAS. Here, we have surveyed all of the aging patients with FXS that we have followed over the years to clarify the medical complications of aging seen in those with FXS. Data was collected from 62 individuals with the FXS full mutation (44 males; 18 females) who were at least 40 years old at their most recent clinical examination. We found that the five most frequent medical problems in these patients were neurological problems (38.7%), gastrointestinal problems (30.6%), obesity (28.8%), hypertension (24.2%) and heart problems (24.2%). Movement disorders were significantly different between males and females (38.6% vs.10.2%, p = 0.029). We did not find any differences in medical problems between those with a full mutation and those with mosaicism. Identification of medical problems associated with aging in FXS is important to establish appropriate recommendations for medical screening and treatment considerations.

Early onset of neurological symptoms in fragile X premutation carriers exposed to neurotoxins.

We present four cases of fragile X premutation carriers with early neurological symptoms, including symptoms consistent with multiple sclerosis (MS) and fragile X-associated tremor/ataxia syndrome (FXTAS). Each patient had significant exposure to one or more environmental neurotoxicants that have documented neurotoxicity (i.e. hexachlorocyclopentadiene or C56, Agent Orange, and 2,4- or 2,6-toluene diisocyanate and dichlormate). We hypothesize that premutation carriers are a vulnerable group to neurotoxins because elevated mRNA in the premutation can lead to early cell death and brain disease, leading to neuropsychiatric and neurological symptoms consistent with FXTAS.

A review of fragile X premutation disorders: expanding the psychiatric perspective.

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 the premutation carrier state (55-200 CGG repeats) of the fragile X mental retardation 1 (FMR1) gene. DATA SOURCES: The search for the psychiatric clinical manifestations of fragile X-associated conditions was accomplished by PubMed for clinical papers published between 1970 and 2008 with the following search terms: Fragile X syndrome, depression, psychosis, anxiety, and dementia. STUDY SELECTION: Articles addressing psychiatric symptoms in premutation carriers based on review of the abstracts were reviewed. As the majority of the literature on this topic is based on case reports and small case series, these were included in the database. RESULTS: Reported clinical manifestations of psychiatric illness in premutation carriers include an apparently significant rate of cognitive, mood, anxiety, and other psychiatric disorders. Fragile X premutation-associated conditions are part of the clinical differential diagnosis of several psychiatric syndromes, particularly in pedigrees with known fragile X syndrome cases. CONCLUSIONS: Fragile X-associated psychiatric manifestations serve as a useful model for a molecular genesis of neuropsychiatric illness. Because of the multigenerational expression of fragile X-associated neuropsychiatric illness, there is a prominent role for genetic testing and genetic counseling of patients and their relatives. Genetic testing is confirmatory of the FMR1 premutation and is an essential component of the clinical evaluation. Psychopharmacologic and psychotherapeutic treatment of fragile X-associated psychiatric illnesses may improve patient function and assist in adaptation to the burden of a genetic neuropsychiatric illness.

Advances in the treatment of fragile X syndrome.

The FMR1 mutations can cause a variety of disabilities, including cognitive deficits, attention-deficit/hyperactivity disorder, autism, and other socioemotional problems, in individuals with the full mutation form (fragile X syndrome) and distinct difficulties, including primary ovarian insufficiency, neuropathy and the fragile X-associated tremor/ataxia syndrome, in some older premutation carriers. Therefore, multigenerational family involvement is commonly encountered when a proband is identified with a FMR1 mutation. Studies of metabotropic glutamate receptor 5 pathway antagonists in animal models of fragile X syndrome have demonstrated benefits in reducing seizures, improving behavior, and enhancing cognition. Trials of metabotropic glutamate receptor 5 antagonists are beginning with individuals with fragile X syndrome. Targeted treatments, medical and behavioral interventions, genetic counseling, and family supports are reviewed here.

Treatment of fragile X-associated tremor ataxia syndrome (FXTAS) and related neurological problems.

Fragile X-associated tremor/ataxia syndrome (FXTAS) is a progressive neurological disorder that affects older adult carriers, predominantly males, of premutation alleles (55 to 200 CGG repeats) of the fragile X (FMR1) gene. Principal features of FXTAS are intention tremor, ataxia, parkinsonism, cognitive decline, and peripheral neuropathy; ancillary features include, autonomic dysfunction, and psychiatric symptoms of anxiety, depression, and disinhibition. Although controlled trials have not been carried out in individuals with FXTAS, there is a significant amount of anecdotal information regarding various treatment modalities. Moreover, there exists a great deal of evidence regarding the efficacy of various medications for treatment of other disorders (eg, Alzheimer disease) that have substantial phenotypic overlap with FXTAS. The current review summarizes what is currently known regarding the symptomatic treatment, or potential for treatment, of FXTAS.

Two boys with fragile x syndrome and hepatic tumors.

Hepatic tumors are rare childhood neoplasms with uncertain etiology. We report the cooccurrence of hepatic tumors in 2 boys with fragile X syndrome, one with hepatoblastoma and another with desmoplastic nested spindle cell tumor of liver. The pathogenesis of fragile X syndrome involves silencing of the fragile X mental retardation 1 gene and consequent loss of FMR1 protein. We speculate regarding molecular pathways that might explain the cooccurrence of the 2 conditions. Further examination of a possible functional link between hepatic neoplasia and loss of FMRP is warranted.

A girl with fragile X premutation from sperm donation.

We present a girl with the fragile X premutation who obtained the premutation allele from donated sperm. Our patient has clinical characteristics of fragile X syndrome including emotional problems and neuropsychological difficulties presenting as learning disabilities. She is also at high risk for premature ovarian failure and low risk for the fragile X-associated tremor ataxia (FXTAS). We suggest fragile X DNA screening in gamete donor candidates to decrease the chance of fragile X involvement in their offspring.

Fragile X syndrome with anxiety disorder and exceptional verbal intelligence.

Fragile X syndrome (FXS) is often characterized by mental retardation. However, FXS is also associated with significant emotional and psychiatric problems, including anxiety, depression, attention difficulties, and learning disabilities in the presence of a normal IQ. This report describes a unique woman with the full mutation of FXS who has an exceptional profile of above-average intelligence combined with significant impairments due to anxiety and learning disability. Women with FXS can present primarily with learning and emotional problems, and clinicians should consider FXS in these women regardless of their IQ.