Folic acid therapy in the fragile X syndrome

Molecular medicine of fragile X syndrome: based on known molecular mechanisms

BACKGROUND

Extensive research on fragile X mental retardation gene knockout mice and mutant Drosophila models has largely expanded our knowledge on mechanism-based treatment of fragile X syndrome (FXS). In light of these findings, several clinical trials are now underway for therapeutic translation to humans.

DATA SOURCES

Electronic literature searches were conducted using the PubMed database and ClinicalTrials.gov. The search terms included "fragile X syndrome", "FXS and medication", "FXS and therapeutics" and "FXS and treatment". Based on the publications identified in this search, we reviewed the neuroanatomical abnormalities in FXS patients and the potential pathogenic mechanisms to monitor the progress of FXS research, from basic studies to clinical trials.

RESULTS

The pathological mechanisms of FXS were categorized on the basis of neuroanatomy, synaptic structure, synaptic transmission and fragile X mental retardation protein (FMRP) loss of function. The neuroanatomical abnormalities in FXS were described to motivate extensive research into the region-specific pathologies in the brain responsible for FXS behavioural manifestations. Mechanism-directed molecular medicines were classified according to their target pathological mechanisms, and the most recent progress in clinical trials was discussed.

CONCLUSIONS

Current mechanism-based studies and clinical trials have greatly contributed to the development of FXS pharmacological therapeutics. Research examining the extent to which these treatments provided a rescue effect or FMRP compensation for the developmental impairments in FXS patients may help to improve the efficacy of treatments.

A combination of ascorbic acid and α-tocopherol to test the effectiveness and safety in the fragile X syndrome: study protocol for a phase II, randomized, placebo-controlled trial

Background

Fragile X syndrome (FXS) is an inherited neurodevelopmental condition characterised by behavioural, learning disabilities, phisical and neurological symptoms. In addition, an important degree of comorbidity with autism is also present. Considered a rare disorder affecting both genders, it first becomes apparent during childhood with displays of language delay and behavioural symptoms.

Main aim: To show whether the combination of 10 mg/kg/day of ascorbic acid (vitamin C) and 10 mg/kg/day of α-tocopherol (vitamin E) reduces FXS symptoms among male patients ages 6 to 18 years compared to placebo treatment, as measured on the standardized rating scales at baseline, and after 12 and 24 weeks of treatment.

Secondary aims: To assess the safety of the treatment. To describe behavioural and cognitive changes revealed by the Developmental Behaviour Checklist Short Form (DBC-P24) and the Wechsler Intelligence Scale for Children–Revised. To describe metabolic changes revealed by blood analysis. To measure treatment impact at home and in an academic environment.

Methods/Design

A phase II randomized, double-blind pilot clinical trial. Scope: male children and adolescents diagnosed with FXS, in accordance with a standardized molecular biology test, who met all the inclusion criteria and none of the exclusion criteria. Instrumentation: clinical data, blood analysis, Wechsler Intelligence Scale for Children–Revised, Conners parent and teacher rating scale scores and the DBC-P24 results will be obtained at the baseline (t0). Follow up examinations will take place at 12 weeks (t1) and 24 weeks (t2) of treatment.

Discussion

A limited number of clinical trials have been carried out on children with FXS, but more are necessary as current treatment possibilities are insufficient and often provoke side effects. In the present study, we sought to overcome possible methodological problems by conducting a phase II pilot study in order to calculate the relevant statistical parameters and determine the safety of the proposed treatment. The results will provide evidence to improve hyperactivity control and reduce behavioural and learning problems using ascorbic acid (vitamin C) and α-tocopherol (vitamin E). The study protocol was approved by the Regional Government Committee for Clinical Trials in Andalusia and the Spanish agency for drugs and health products.

Trial registration

ClinicalTrials.gov Identifier: NCT01329770 (29 March 2011)

Folic acid for fragile X syndrome

BACKGROUND

It has been argued that individuals with fragile X syndrome could have low folate levels in their bodies and that supplementing their dietary intake might remediate the adverse developmental and behavioural effects of the condition.

OBJECTIVES

To review the efficacy and safety of folic acid in the treatment of people with fragile X syndrome.

SEARCH STRATEGY

We searched four databases in November 2010: CENTRAL, PubMed, EMBASE and PsycINFO.

SELECTION CRITERIA

Randomised controlled trials.

DATA COLLECTION AND ANALYSIS

Two review authors independently extracted data and assessed risk of bias using the Cochrane 'Risk of bias' tool.

MAIN RESULTS

We included five trials, which were published between 1986 and 1992. Overall, they included 67 patients, all male, with ages ranging from one to 54 years. Intellectual disability in participants varied from borderline to severe and some studies included patients with an additional diagnosis of autism or autistic behaviour. Four of the studies were placebo-controlled cross-over trials and one study was a parallel design. The duration of follow-up ranged from two months to 12 months and the period on folic acid or placebo ranged from two to eight months. Doses of folic acid ranged from 10 mg to 250 mg per day, 10 mg per day being the most common. Most of the younger patients involved were also taking part in special education programmes (usually involving language and occupational therapy).We were not able to perform meta-analysis to combine results but none of the individual studies found evidence of clinical benefit with the use of folic acid medication in fragile X syndrome patients on any of the areas of interest, either psychological and learning capabilities or behaviour and social performance, as measured with standardised tools. Separate analysis of evidence for patients of different age groups, i.e. prepubertal children and postpubertal young people, found some statistically significant results, but did not show clear evidence of benefit for either group. Adverse effects of folic acid treatment were rare, not serious and transient.Studies were generally poorly reported and we classified only one study as being at low risk of bias.

AUTHORS' CONCLUSIONS

The quality of available evidence is low and not suitable for drawing conclusions about the effect of folic acid on fragile X syndrome patients. It consists of few studies with small samples of patients, all of them male, with little statistical power to detect anything other than huge effects.

Treatments for fragile X syndrome: a closer look at the data

Research into the determinants and developmental course of fragile X syndrome (FXS) has made remarkable progress over the last 25 years. However, treatments to ameliorate the symptoms of FXS have been less forthcoming. While there is optimism in the field that the pace of intervention research is quickening, there has been a bias toward psychopharmacological approaches to treatment. A closer look at the data from those investigations reveals a paucity of evidence that medications can improve intellectual and adaptive functioning in FXS, or decrease associated behavioral and/or emotional issues. Work in other related disorders (e.g., autism) has shown that dramatic improvements in intellectual and adaptive functioning, as well as behavioral and emotional problems, can occur if intensive behavioral treatment is begun early in the child's life. It is hoped that future research efforts will evaluate these intensive early intervention strategies in children with FXS, perhaps in combination with pharmacological approaches.

Systematic review of pharmacological treatments in fragile X syndrome

Background

Fragile X syndrome (FXS) is considered the most common cause of inherited mental retardation. Affected people have mental impairment that can include Attention Deficit and/or Hyperactivity Disorder (ADHD), autism disorder, and speech and behavioural disorders. Several pharmacological interventions have been proposed to treat those impairments.

Methods

Systematic review of the literature and summary of the evidence from clinical controlled trials that compared at least one pharmacological treatment with placebo or other treatment in individuals with diagnosis of FXS syndrome and assessed the efficacy and/or safety of the treatments. Studies were identified by a search of PubMed, EMBASE and the Cochrane Databases using the terms fragile X and treatment. Risk of bias of the studies was assessed by using the Cochrane Collaboration criteria.

Results

The search identified 276 potential articles and 14 studies satisfied inclusion criteria. Of these, 10 studies on folic acid (9 with crossover design, only 1 of them with good methodological quality and low risk of bias) did not find in general significant improvements. A small sample size trial assessed dextroamphetamine and methylphenidate in patients with an additional diagnosis of ADHD and found some improvements in those taking methylphenidate, but the length of follow-up was too short. Two studies on L-acetylcarnitine, showed positive effects and no side effects in patients with an additional diagnosis of ADHD. Finally, one study on patients with an additional diagnosis of autism assessed ampakine compound CX516 and found no significant differences between treatment and placebo. Regarding safety, none of the studies that assessed that area found relevant side effects, but the number of patients included was too small to detect side effects with low incidence.

Conclusion

Currently there is no robust evidence to support recommendations on pharmacological treatments in patients with FXS in general or in those with an additional diagnosis of ADHD or autism.

Fragile X syndrome: assessment and treatment implications

Fragile X syndrome (FraX) is the most common known cause of inherited mental impairment. FMR1 gene mutations, the cause of FraX, lead to reduced expression of FMR1 protein and an increased risk for a particular profile of cognitive, behavioral, and emotional dysfunction. The study of individuals with FraX provides a unique window of understanding into important disorders such as autism, social phobia, cognitive disability, and depression. This review highlights the typical phenotypic features of individuals with FraX, discussing the apparent strengths and weaknesses in intellectual functioning, as evidenced from longitudinal follow-up studies. It also discusses recent neuroanatomic findings that may pave the way for more focused disease-specific pharmacologic and behavioral interventions. This article describes the results of recent medication trials designed to target symptoms associated with FraX. It also describes some recent behavioral interventions that were conducted in our laboratory.

Typical neuroleptics in child and adolescent psychiatry

This paper reviews the use of typical ("old") neuroleptics in the treatment of child and adolescent psychiatric disorders. Very few methodologically sound papers have been published in the field. It is concluded that typical neuroleptics should be used sparingly and only in severe and incapacitating disorders such as some psychotic conditions and handicaping tic disorders. Side effects have to be very carefully monitored.

Where have all the fragile X boys gone?

A four-year retrospective survey of individuals referred for fragile X testing to South East Thames Regional Genetics Service was carried out to determine the accuracy of clinical diagnosis of fragile X syndrome among routine referrals for cytogenetic confirmation. 680 individuals from 565 pedigrees were tested for fragile X. Five affected males were identified in previously unknown families and 17 new pedigrees were diagnosed. Using the accepted prevalence data, a total of 80 affected males would have been expected in this period. The most likely explanation for the low diagnosis rate is failure of referral of affected males.

Fragile X syndrome

Fragile X syndrome is one of the most intriguing genetic conditions now being studied. As the most common inherited form of mental retardation, it has an incidence of approximately 1 in 1000 male infants and boys. Because the cytogenetic diagnosis has only recently been available, many affected boys and female carriers have not yet been identified. This article reviews the characteristic, clinical features of fragile X syndrome and discusses treatment and intervention.

Constitutive fragile sites in fra(X) individuals

Recently, it was proposed that the constitutive fragile site at 3p14 be used as an "internal control" to indicate the effectiveness of the FUdR fragile site induction system. We have tested this hypothesis by determining the frequency of constitutive fragile sites at 1p31, 3p14, and 16q23 in cultures from 42 known fra(X) individuals. At least 50 cells were analyzed from each case. Seventy-four percent (31/42), 95% (40/42) and 90% (38/42) of the fra(X) individuals exhibited frequencies of less than 4% at constitutive fragile sites 3p14, 1p31 and 16q23, respectively. Of the 42 individuals tested, 12 or 28.6% showed no fragility at any of the 3 sites studied. On the other hand, at least one constitutive fragile site was observed in 50 cells studied from over 70% of the 42 people studied. It is suggested that "positive controls" continue to be used, while at the same time recording all fragile sites to identify a combination of constitutive fragile sites that may serve as an internal control indicator, and that DNA marker studies be used to complement cytogenetic testing.

Folic acid treatment of fragile X males: a further study

Investigations of the effect of high dose folic acid treatment of fragile X syndrome in males has produced mixed results. However, no study had examined the possible drug effects of folic acid on non-fragile X control males. Therefore, we examined the effect of folic acid on fragile X males using non-fragile X control males. Subjects were assigned randomly to an ABA or BAB design. Duration of either folic acid or placebo condition was 4 months. Folic acid or placebo was given in a double-blind fashion. At the end of each condition, the subjects' behavior was assessed. At the end of the study, parents were asked to complete a questionnaire. Using parents' responses, we examined 22 items on the Autistic Descriptors Checklist and two subscales from the Vineland Adaptive Behavior Scale which corresponded to areas of behavior parents' noted to have shown improvement. We did not find significant differences between fragile X males and control males, within subjects, nor across folic acid and placebo conditions. Thus, our follow-up study confirms and extends our original findings, as well as those of other researchers: namely, that no dramatic changes in behavior result from high dose folic acid. Moreover, subtle improvements observed in earlier investigations were not confirmed.

A controlled trial of stimulant medication in children with the fragile X syndrome

Attentional deficits and hyperactivity frequently are major problems for fra(X) boys. This study evaluated the effectiveness of 2 stimulant medications, methylphenidate and dextroamphetamine compared to placebo in 15 children (13 males, 2 females) with the fra(X) syndrome. A double-blind crossover design was used with outcome measures which included parent and teacher behavior checklists, a controlled observation period, continuous performance tasks and an actometer measure of movement. When the children were treated with methylphenidate only, improvement was seen in socialization skills and attention span according to teacher checklists. Ten children were clinically considered responders and treatment was continued after the study was completed.

The fragile-X syndrome

The variability in behavioral manifestations of the fragile-X syndrome and the lack of a well-defined psychological profile require the attention of behavioral geneticists and other behavioral scientists. The association with autism suggests that the fra(X) may be responsible for a genetic subtype of autism. While the fragile-X syndrome is considered an X-linked disorder, several aspects of observed transmission patterns do not follow those of classical X-linked inheritance. In particular, the finding of genetic transmission via intellectually normal males is surprising and has important implications for genetic counseling, as well as for genetic models of the fragile-X syndrome. Reports on folic acid treatment are encouraging, but not conclusive. The mechanisms involved in the association between the fra(X) chromosome and its particular phenotype are still unknown. Current investigations applying advanced techniques in molecular biology are likely to provide insight into this unique genetic disorder.

Fragile X syndrome

The fragile X syndrome is the most common inherited form of mental retardation known. Its phenotype includes large or prominent ears, macroorchidism, and characteristic behavioral problems. It has attracted the interest of cytogeneticists and molecular biologists because of its characteristic fragile site on the X chromosome. It has puzzled geneticists because of its unusual inheritance pattern involving nonpenetrant males. This syndrome has also spearheaded an appreciation of cytogenetic abnormalities in the etiology of all degrees of developmental delay.

Hypothesis regarding the nature of the fragile X mutation. A reply to Winter and Pembrey

Pembrey et al. (1985) proposed a hypothesis regarding the nature of the fragile X [fra(X)] mutation. Recently they analyzed DNA linkage data (Winter and Pembrey 1986) that we and others have published on fra(X) pedigrees, found significant linkage heterogeneity, and modified their hypothesis to explain the observations. We would like to point out that their modified hypothesis is not supported by the data available.

Folic acid treatment in males and females with fragile-(X)-syndrome

Ten males with the fragile X (fra(X] syndrome were treated with folic acid (10 mg/day) for 4 months in a double-blind design study. To eight heterozygotes with mental impairment and fra(X), folic acid was given for 4 months (10 mg/day) in an effort to study possible beneficial effects of folic acid. Psychological and cytogenetic testing were carried out during the trial. There was no improvement in concentration, fine motor co-ordination, or comprehension in the adult male and female patients of the study. One patient showed improvement under a control medications. In the females, improvement was seen only in the youngest patient, a 5-year-old girl. Folate treatment does not seem to be effective in fra(X) adults, but may have some effect in children of both sexes with the disorder. Cytogenetic studies using peripheral lymphocytes showed that the fra(X) frequency decreased significantly (t = 0.00856; 1% level) only in cells cultured in a folic acid-free medium but not in cells cultured in a medium with added antifolate (methotrexate). This shows a "contamination effect" of folate-free culture medium after oral folic acid treatment of these patients. The decrease of fra(X) involves primarily the early-replicating X when culturing with folic acid-free medium. A synergistic suppression effect of "external folate" and BrdU is the most likely explanation of this phenomenon.

High dose folic acid treatment of fragile (X) males

We conducted an experimental trial of high-dose folic acid given to five males, ages 8 to 26 years, with the fra(X) syndrome. In this double blind study, each subject received 250 mg per day of folic acid for 3 months, followed by placebo for 3 months, and folic acid again for an additional three months. Based on IQ tests, behavior ratings, the Autistic Descriptors Checklist, and parental ratings, there was little evidence to suggest any positive effects seen during the administration of high-dose folic acid. Therefore, this study has provided little support for a hypothesis of benefit of high-dose folic acid in the treatment of the fra(X) syndrome.

Variability of thymidylate synthase activity in whole blood cultures treated with FUdR

Induction of some fragile sites including fragile X [fra(X)] depends on the depletion of thymidine monophosphate (TMP) from the culture medium. This can be accomplished by use of inhibitors such as 5-fluorodeoxyuridine (FUdR) and by culturing cells in medium deficient in folate and TMP. FUdR inhibits the activity of thymidylate synthase (TS), thereby depleting cells of TMP. To determine the degree of FUdR inhibition of TS under routine cytogenetic culture conditions, we modified the tritiated dUMP TS method for use in short-term whole blood cultures stimulated with phytohemagglutinin. TS inhibition was highly variable across whole blood cultures from 30 individuals exposed to FUdR during the last 24 hours of a 4 day culture. If an additional dose of FUdR was added 12 hours before harvest, TS inhibition usually increased. These findings have a potential impact on the use of FUdR for the diagnosis of the fra(X) syndrome.

Oral folic acid versus placebo in the treatment of males with the fragile X syndrome

A double-blind, crossover study of a 10 mg folic acid per day (vs. placebo) treatment was carried out in 25 fra(X) males (ages 1-31 years). Each treatment period lasted 6 months. Before, during and after the study, the patients were assessed blindly with psychological, language and behavioral evaluations, and parent or caretaker reports were collected. Standardized testing did not show statistically significant changes in the group as a whole; psychological testing demonstrated a statistically significant improvement on folic acid in the prepubertal males. After uncoding, caretaker or parent reports also demonstrated behavioral improvements in the prepubertal males while being treated with folic acid.

Frequency of tri- or multiradial configurations in fragile X identification

Using the FUdR system for fragile X induction, we have observed no triradial or bisatellited configurations at fra (X) (q27.3) in over 5,000 fra(X) chromosomes examined from over 150 fra(X) individuals. Based on our observations, and those of Turner and Jacobs (1983) and Daniel et al (1984), we hypothesize that triradial configurations may not occur at Xq27 with FUdR induction. To test this hypothesis we cultured whole blood simultaneously in parallel folate-deficient and FUdR fra(X) induction systems, and systematically examined fra(X) chromosomes for triradials. Neither autosomes nor X chromosomes exhibited any apparent triradial figures in the FUdR system, while 1.4% of the fra(X) chromosomes in TC 199 exhibited a triradial. Also we observed one autosomal triradial at 4q35. We conclude that triradial configurations occur in low frequencies in the folate deficient system and seldom if ever in the FUdR system.

Heritable fragile sites on human chromosomes. XII. Population cytogenetics

Chromosome studies to detect the folate sensitive fragile sites have been carried out on 2439 randomly selected neonates. Four autosomal fragile sites were detected in this group. Similar studies were carried out on referred patients, special school students and sheltered workshop employees. The incidence of fragile X in these groups was 6/1936, 13/502 and 0/128 respectively. Autosomal folate sensitive fragile sites were seen in 14/1936, 5/502 and 2/128 individuals respectively.

Effect of folic acid treatment in the fragile X syndrome

The effect of folic acid intake on the frequency of fragile X positive cells and some behavioural characteristics were evaluated in 5 boys and 4 adult males with the fragile X syndrome. The expression of fragile X was nullified in 6 and decreased in 3 of the 9 patients. Behavioural and motor ability were considered to have improved in 4 of the 5 boys but not in the 4 adults with fragile X syndrome.