The objective of these recommendations is to contribute to the dissemination of knowledge on FXS among health professionals, and thus improve the diagnosis and management of these patients.

The meeting on formulation of National consensus guidelines on Fragile X syndrome was organized by Indian Academy of Pediatrics in New Delhi on 25th February 2017. The invited experts included Pediatricians, Developmental Pediatricians, Psychiatrists, Pediatric Neurologists, Geneticists, Obstetrician and Gyneco-logists, Clinical Psychologists, Remedial Educators, and members of Parent Organizations. Guidelines were framed after extensive discussions. A writing committee was formed that drafted the manuscript, circulated these among members for critical appraisal, and finalized the recommendations.

Clinicians should have a high index of suspicion in any male with intellectual disability (ID) or autistic spectrum disorder (ASD). These children should be examined for the characteristic facial features (long narrow face, prominent jaw, large and protruded ears) and macro-orchidism. Various phenotypic characteristics that can be observed in FXS patients are detailed in Table I. Chronic and recurrent otitis media starting early in life is a common observation because of a more collapsible eustachian tube promoting fluid collection and bacterial overgrowth [5]. Seizures have been reported in approximately 13% to 18% with a higher prevalence in male patients. The clinical phenotype of FXS depends on the amount of FMRP produced, which is related to the number of CGG repeats and to the degree of FMR1 methylation resulting in characteristic phenotype. Therefore, in a prepubertal boy there may only be prominent ears and hyperextensible finger joints with soft skin so that the diagnosis is suggested mainly by behavioral features such as poor eye contact, handflapping, handbiting and anxiety. We recommend that all children with intellectual disability, developmental delay or ASD should have the fragile X DNA test because sometimes the physical features are not obvious or not present, particularly in young children.

TABLE I	Phenotypic Features That may be Seen in Fragile X Syndrome Patients

The cognitive profile in a child with FXS varies from mild to severe intellectual disability depending upon CGG (cytosine-guanine-guanine) expansion located in the 5’ UTR (Untranslated Region) of the fragile X mental retardation 1 (FMR1) gene and the methylation status [2,6]. Average IQ being 40 in males with a completely methylated full mutation. While most females with FXS have a borderline IQ, about 25% of them have an IQ less than 70 and rest 25% have a normal IQ but more learning and emotional problems [7]. Thus, clinicians should have a high index of suspicion for FXS in a boy with developmental delay, language delay and hypotonia in early childhood, and in a female child with low IQ and positive family history.

Features of attention-deficit/ hyperactivity disorder (ADHD), including hyperactivity, inattentiveness, distractibility, restlessness, and impulsivity are cautiously assessed in a child with ID as they are a common behavioral phenotype present in about 80% of boys and 40% of girls with FXS. Anxiety-related symptoms including obsessive-compulsive–like and perseverative behaviors, and emotional lability are also common along with aggressive, self-injurious behavior and frequent temper tantrums. Features of autism are usually present in early childhood, including stereotypies such as hand-flapping, biting, perseverative speech, poor eye contact, and lack of interest in social interaction [8]. However, only 50 to 60% of boys and 20% of girls with FXS meet diagnostic criteria for ASD.

The pattern of FXS inheritance is not a classic Mendelian inheritance pattern due to the dynamic repeat expansion. The expansion from pre-mutation to full-mutation alleles occurs during the transmission of the maternal X chromosome carrying pre-mutation, to her children and depends on the mother’s pre-mutation CGG repeat size; the higher the repeat size, greater is the risk of expansion to a full-mutation allele [9-11]. Various allele groups with their respective clinical manifestations in FXS are shown in Table II. The final phenotype also depends upon the on the Activation Ratio (AR) which expresses the percentage or ratio of cells with the normal allele present on active X chromosome, so that higher AR correspond to higher FMRP expression levels produced by the normal FMR1 allele [6]. Hence, females have a wider range of phenotype varying from typical physical features with intellectual impairment to mild learning disability with absent physical characteristics. [12]. So, it is recommended to keep a low threshold for testing for FXS in female with a positive family history.

TABLE II  Allele Groups With Their Respective Clinical Manifestations in Fragile X Syndrome (FXS)

There are other FMR1 gene-related disorders in which the carriers of a pre-mutation typically have normal IQ and little or no features of FXS. However, they are at risk for developing the Fragile X-associated tremor/ataxia syndrome (FXTAS) [13], and the Fragile X-associated primary ovarian insufficiency (FXPOI) [14]. In addition, they may be at risk for other medical conditions like depression, anxiety, migraine headaches, hypertension, insomnia, sleep apnea, immune mediated diseases including hypothyroidism and fibromyalgia, chronic fatigue and chronic pain syndrome, but the prevalence of these problems varies from 10%-50% and the symptoms depend on the age and sex of the individual [13,15]. These manifest later in adulthood and we recommend that they be explained to parents as a part of prognosis.

Conventional cytogenetic techniques using the light microscope (which allowed the observation of the distal narrowing of the long arm of the X chromosome at the band 27.3) were previously used for the diagnosis of FXS. These narrowed segments were known as the fragile sites. Nowadays, more sensitive and specific molecular tests are available which allow diagnosis of full-mutation and pre-mutation carriers, by determining the number of repeats and the methylation status of the regulatory region. The gold standard DNA testing for the diagnosis of FXS is a combination of Polymerase chain reaction (PCR) and Southern blot analysis and are the recommended methods for FXS laboratory confirmation. PCR uses specific primers for the FMR1 gene and can identify patients with an expanded FMR1 allele in both the full-mutation and pre-mutation range [16]. Southern blot analysis identifies alleles throughout the mutation ranges and allows the determination of the methylation status. The consensus committee recommends that all children presenting with intellectual disability and/ or developmental delay and/or ASD with no known diagnosis should have FMR1 DNA testing. We also believe that if there are typical facial features, a positive family history of intellectual disability, or macro-orchidism then there is an increased chance of obtaining a positive result. If the genetic test supports the diagnosis of FXS in the proband, family screening should be offered with special attention to family members with tremor, ataxia, neurological symptoms or early ovarian insufficiency. The clinician or genetic counselor should be careful about identifying the mother as the carrier as there is a risk of stigmatizing. The consensus committee recommends that the same molecular tests can be used for diagnosis of a fragile X mutation in the fetus of pregnant carrier mother on chorionic villus or amniotic fluid sampling. For developmental delays and intellectual disability in children with phenotype not strongly suspicious of FXS, chromosomal microarray is recommended as first tier test (screening test) and will identify a number of chromosomal disorders such as DiGeorge (22q11.2 deletion) syndrome [17]. If chromosomal microarray is not conclusive, such children should have the fragile X DNA test because sometimes the physical features are not obvious or not present, particularly in young children. Hence we recommend that in all children with developmental delays and intellectual disability having phenotype not strongly suspicious of FXS, chromosomal microarray is recommended as first tier test (screening test) followed by fragile X DNA test (if microarray remains inconclusive).

Fig. 1 Algorithm for diagnosis of Fragile X syndrome.

TABLE III  Main Differentials of Freigile X Syndrome in View of Intellectual Disability 

LBW: Low birth weight; PCR: Polymerase chain reaction; FISH: Flourescent in-situ hybridization.

Approach to FXS diagnosis is shown in Fig. 1 and the differential diagnosis of FXS is listed in Table III.

The diagnostic test for FXS is highly accurate. Diagnosing FXS establishes the reason of cognitive deficits and/ or behavioral problems in a child. It allows the parents and/or caregivers to gain an understanding of the disorder and how it affects the child’s development and behavior. This would assist in focused management to maximize their child’s potential. Diagnosing FXS would help at-risk families to decide on their appropriate management of family planning and future pregnancies. They could benefit from options of prenatal diagnosis if appropriate for them.

Indications for molecular genetic tests/confirmatory tests for FXS: The consensus committee recommends to perform molecular genetic tests in following conditions:

The committee also feels that tests for FXS may be considered and should be performed in situations mentioned below:

Supportive strategies including speech therapy, occupational therapy, special educational services and behavioral interventions are key to managing children with FXS and the consensus committee strongly recommend for the same.

TABLE IV  Recommendations for Age-appropriate Health Supervision in Fragile X Syndrome

Recommendations for age appropriate health supervision and interventions and mentioned in Table IV.

TABLE V Drugs Used in Fragile X Syndrome

Medications play a role to control symptoms of ADHD, aggressive episodes, self-injurious behavior and anxiety-related issues as shown in Table V. Modifying these symptoms with medications significantly improves an affected child’s ability to participate more successfully in activities in home and school settings. The consensus committee recommends the judicious use of medications for symptom-control under the care of a specialist health care provider. New targeted treatments that have the potential to reverse the neurochemical abnormalities in FXS have been developed and a few are available by prescription currently. The early use of low dose sertraline (2.5 to 5.0 mg/day) in young children with FXS between the ages of 2 to 6 years has demonstrated efficacy in improving aspects of development on the Mullen Scales of Early Learning compared to placebo [18]. For those on sertraline, significant improvements in visual perception, fine motor and composite T scores were seen compared to placebo and in a post hoc analysis, those with FXS and ASD on sertraline demonstrated a significant improvement in expressive language compared to those on placebo. Generally this treatment is well tolerated without significant side-effects, except that approximately 20% of children with FXS treated with sertraline can develop a significant increase in hyperarousal such that the dose must be lowered or discontinued.

Minocycline is also a targeted treatment for FXS because it can lower the increased levels of MMP9, which interfere with appropriate synaptic connections. A controlled trial of minocycline in children with FXS demonstrated improvements in behavior for those aged 3.5 to 16 years [19]. However, minocycline given in a dose of 25 to 100 mg a day depending on age can sometimes lead to darkening of the permanent teeth if started before 8 years. In addition, darkening of the nail beds, gums or skin may occasionally occur with prolonged treatment. Minocycline can rarely lead to a lupus like syndrome with a rash and/or swollen joints and this corresponds to significant elevation of the antinuclear antibody (ANA). If these symptoms occur, then minocycline should be discontinued; the symptoms usually resolve [19]. More recently, the use of metformin has been identified as a targeted treatment for FXS because it lowers the MEK-ERK pathway and in animal models for FXS it rescues many of the features of FXS. A recent report of seven patients treated with metformin clinically demonstrated improvement in behavior and language [20]. A controlled trial of metformin is underway for children and adults with FXS to better understand the benefits for behavior and cognition. Metformin is currently FDA approved for treatment of obesity and type 2 diabetes, so it may be considered if these problems are present in a patient with FXS.

Recurrent otitis media may lead to conductive hearing loss and additional language and articulation problems, and therefore there should be a low threshold for early placement of pressure equalizing tubes in children with FXS and recurrent otitis media [5]. Tonsillectomy or adenoidectomy may be considered if chronically infected tonsils or adenoids are present or the child has sleep apnea. The consensus committee recommends a consultation with ENT specialist once diagnosis of FXS is established for early care of hearing and speech.

Genetic counseling is recommended for all family members who are affected or at risk of having a pre-mutation (PM) or an offspring with a full-mutation (FM). It is important to highlight the variability of the clinical phenotype and offer molecular diagnosis. Females who are PM carriers have a risk of transmitting the FM to their offspring. That risk depends on the mother’s CGG repeat size and she can be counseled using that information [9-11]. Males with PM will pass their expanded allele to all daughters but none to their sons. The father’s PM can expand and sometimes contract, but it stays within the PM range. Adults with a PM should be counseled about their risk of developing ataxia (FXTAS), ovarian insufficiency (FXPOI), anxiety, depression or other medical problems that can occur in PM carriers [13,14]. Males with FM transmit only PM size alleles to their daughters. The current understanding is that the large repeat size of a FM cannot be maintained during spermatogenesis. The consensus committee recommends genetic counseling for all family members who are affected or at risk of having a PM or an offspring with a FM.

Fragile X syndrome is an important cause of intellectual disability and ASD, with a broad spectrum of clinical phenotypes. Early diagnosis and timely intervention, genetic and reproductive counseling, access to behavioral and pharmacological treatment, and to services are key to attain optimal outcomes. Behavioral modifications and management of co-morbidities could help these children to lead a more productive life. The consensus committee recommends that all children presenting with intellectual disability and/or developmental delay and/or ASD with no known diagnosis should have FMR1 DNA testing. The same molecular tests should be used for diagnosis of a fragile X mutation in the fetus of pregnant carrier mother on chorionic villus or amniotic fluid sampling. We recommend that in all children with developmental delay and intellectual disability having phenotype not strongly suspicious of FXS, chromosomal microarray is recommended as first tier test (screening test) followed by fragile X DNA test (if microarray remains inconclusive). Early use of supportive strategies including speech therapy, occupational therapy, special educational services and behavioral interventions are key measures to manage children with FXS. Medications should be used judiciously for control of symptoms under the care of a specialist health care provider. We recommend genetic counseling for all family members who are affected or at risk of having a pre-mutation or an offspring with a full-mutation.

Contributors: PJ, AS: prepared the manuscript; AS, VG, SBM, SM, RH, SS, SK, SNK: analyzed and critically reviewed the manuscript. All authors approved the manuscript.

Funding: None; Competing interests: Shalini N Kedia is the Chairperson and founder member of Fragile X society, which promotes public and professional awareness of Fragile X syndrome, and hold workshops and conferences towards this cause.

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