Targeted treatments in fragile X syndrome

Public Health Literature Review of Fragile X Syndrome

OBJECTIVES

The purpose of this systematic literature review is to describe what is known about fragile X syndrome (FXS) and to identify research gaps. The results can be used to help inform future public health research and provide pediatricians with up-to-date information about the implications of the condition for individuals and their families.

METHODS

An electronic literature search was conducted, guided by a variety of key words. The search focused on 4 areas of both clinical and public health importance: (1) the full mutation phenotype, (2) developmental trajectories across the life span, (3) available interventions and treatments, and (4) impact on the family. A total of 661 articles were examined and 203 were included in the review.

RESULTS

The information is presented in the following categories: developmental profile (cognition, language, functional skills, and transition to adulthood), social-emotional profile (cooccurring psychiatric conditions and behavior problems), medical profile (physical features, seizures, sleep, health problems, and physiologic features), treatment and interventions (educational/behavioral, allied health services, and pharmacologic), and impact on the family (family environment and financial impact). Research gaps also are presented.

CONCLUSIONS

The identification and treatment of FXS remains an important public health and clinical concern. The information presented in this article provides a more robust understanding of FXS and the impact of this complex condition for pediatricians. Despite a wealth of information about the condition, much work remains to fully support affected individuals and their families.

Assistive technology to promote occupation and reduce mouthing by three boys with fragile X syndrome

OBJECTIVES

To extend the use of assistive technology (AT) for promoting a new adaptive response and to reduce hand mouthing, by three boys with fragile X syndrome. To monitor the effects of the intervention program on the positive mood. To carry out a three month follow-up phases. To conduct a social validation assessment involving 30 parents of children who presented multiple disabilities as raters.

METHODS

The study was implemented according to an ABAB experimental design, where A represented baseline phases (technology available but inactive) and B represented intervention phases (the technology ensured 7 s of positive stimulation).

RESULTS

All participants improved and consolidated their performance. Parents involved in the social validation assessment rated positively the use of such technology.

CONCLUSION

AT-based program was useful, affordable, and effective for enhancing constructive engagement, self-determination, and for improving quality of life by children with fragile X syndrome and severe to profound developmental disabilities.

Fragile X syndrome: A review of clinical management

The fragile X mental retardation 1 gene, which codes for the fragile X mental retardation 1 protein, usually has 5 to 40 CGG repeats in the 5' untranslated promoter. The full mutation is the almost always the cause of fragile X syndrome (FXS). The prevalence of FXS is about 1 in 4,000 to 1 in 7,000 in the general population although the prevalence varies in different regions of the world. FXS is the most common inherited cause of intellectual disability and autism. The understanding of the neurobiology of FXS has led to many targeted treatments, but none have cured this disorder. The treatment of the medical problems and associated behaviors remain the most useful intervention for children with FXS. In this review, we focus on the non-pharmacological and pharmacological management of medical and behavioral problems associated with FXS as well as current recommendations for follow-up and surveillance.

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.

Treatment of the psychiatric problems associated with fragile X syndrome

PURPOSE OF REVIEW

This work reviews recent research regarding treatment of fragile X syndrome (FXS), the most common inherited cause of intellectual disability and autism spectrum disorder. The phenotype includes anxiety linked to sensory hyperarousal, hyperactivity, and attentional problems consistent with attention deficit hyperactivity disorder and social deficits leading to autism spectrum disorder in 60% of boys and 25% of girls with FXS.

RECENT FINDINGS

Multiple targeted treatments for FXS have rescued the phenotype of the fmr1 knockout mouse, but few have been beneficial to patients with FXS. The failure of the metabotropic glutamate receptor 5 antagonists falls on the heels of the failure of Arbaclofen's efficacy in children and adults with autism or FXS. In contrast, efficacy has been demonstrated in a controlled trial of minocycline in children with FXS. Minocycline lowers the abnormally elevated levels of matrix metalloproteinase 9 in FXS. Acamprosate and lovastatin have been beneficial in open-label trials in FXS. The first 5 years of life may be the most efficacious time for intervention when combined with behavioral and/or educational interventions.

SUMMARY

Minocycline, acamprosate, lovastatin, and sertraline are treatments that can be currently prescribed and have shown benefit in children with FXS. Use of combined medical and behavioral interventions will likely be most efficacious for the treatment of FXS.

Fragile X syndrome as a rare disease in China - Therapeutic challenges and opportunities

Recognized as the most common inherited from of intellectual disability (ID) and the most common known monogenic cause of autism spectrum disorders (ASD), Fragile X syndrome (FXS) is identified as an unmet medical need for the development of personalized medicine and targeted therapeutics for neurodevelopment disorders as a result of improved understanding of the genetic and cellular mechanisms. Consequently promising pharmacological targets have emerged from basic and translational research, are now being pursued by global pharmaceutical and biotech companies in early proof-of-concept clinical trials. With the world's largest rare disease population, China potentially has a large number of FXS patients, many of whom are under-diagnosed or even misdiagnosed, barely with any treatment. In spite of improved awareness of FXS in recent years, big gaps still exist between China and developed countries in multiple aspects. With increased public awareness, strong government support and investment, coupled with an increasingly large number of Western-trained experienced researchers engaging in new drug discovery and development, China has the potential to become an important player in the discovery of effective diagnostics and treatments for a rare disease like FXS.

Serotonin dysregulation in Fragile X Syndrome: implications for treatment

Fragile X Syndrome (FXS) is a trinucleotide repeat disorder that results in the silencing of the Fragile X Mental Retardation 1 gene (FMR1), leading to a lack of the FMR1 protein (FMRP). FMRP is an mRNA-binding protein that regulates the translation of hundreds of mRNAs important for synaptic plasticity. Several of these pathways have been identified and have guided the development of targeted treatments for FXS. Here we present evidence that serotonin is dysregulated in FXS and treatment with the selective serotonin reuptake inhibitor (SSRI) sertraline may be beneficial for individuals with FXS, particularly in early childhood.

Fragile X spectrum disorders

The fragile X mental retardation 1 gene (FMR1), which codes for the fragile X mental retardation 1 protein (FMRP), is located at Xp27.3. The normal allele of the FMR1 gene typically has 5 to 40 CGG repeats in the 5' untranslated region; abnormal alleles of dynamic mutations include the full mutation (> 200 CGG repeats), premutation (55-200 CGG repeats) and the gray zone mutation (45-54 CGG repeats). Premutation carriers are common in the general population with approximately 1 in 130-250 females and 1 in 250-810 males, whereas the full mutation and Fragile X syndrome (FXS) occur in approximately 1 in 4000 to 1 in 7000. FMR1 mutations account for a variety of phenotypes including the most common monogenetic cause of inherited intellectual disability (ID) and autism (FXS), the most common genetic form of ovarian failure, the fragile X-associated primary ovarian insufficiency (FXPOI, premutation); and fragile X-associated tremor/ataxia syndrome (FXTAS, premutation). The premutation can also cause developmental problems including ASD and ADHD especially in boys and psychopathology including anxiety and depression in children and adults. Some premutation carriers can have a deficit of FMRP and some unmethylated full mutation individuals can have elevated FMR1 mRNA that is considered a premutation problem. Therefore the term "Fragile X Spectrum Disorder" (FXSD) should be used to include the wide range of overlapping phenotypes observed in affected individuals with FMR1 mutations. In this review we focus on the phenotypes and genotypes of children with FXSD.

Participation of underrepresented minority children in clinical trials for Fragile X syndrome and other neurodevelopmental disorders

The purpose of this study was to identify demographic data, motivational factors and barriers for participation in clinical trials (CTs) at the University of California Davis, MIND Institute. We conducted a cross-sectional survey in 100 participants (81 females and 19 males). The participants had high education levels (only 2% had not completed high school), a mean age of 44 years (SD ± 9.899) and had at least one child with a neurodevelopmental disorder. The diagnosis of Fragile X syndrome (FXS) had a significant association with past participation in CTs (p < 0.001). A statistical significance for age of diagnosis and participation in CTs was also found (z = -2.01, p = 0.045). The motivating factors were to help find cures/treatments for neurodevelopmental disorders and to relieve symptoms related to child's diagnosis. Factors explaining lack of participation, unwillingness to participate or unsure of participation were: lack of information/knowledge about the trials, time commitment to participation (screening, appointments, assessments, laboratory tests, etc.) and low annual household income. These results show that a portion of underrepresented minorities (URM) not participating in CTs are willing to participate and suggests that reducing barriers, particularly lack of knowledge/information and time commitment to trials are needed to improve recruitment.