Fragile X Syndrome (FXS)
Fragile X Syndrome is a genetic disorder caused by a mutation in the FMR1 gene (Fragile X Mental Retardation-1). The FMR1 gene is responsible for the production of the FMRP protein. It plays a significant role in developing connections between nerve cells associated with the processes of learning and memory. Mutation in the FMR1 gene stops the body from making FMRP proteins. Therefore, FraX patients suffer from varying levels of mental retardation. Some patients may experience mild learning disabilities, while others have severe clinical courses with physical changes.
What causes Fragile X Syndrome?
The genetic basis for this phenomenon lies in an increased number of trinucleotide repeats (an expansion of CGG nucleotide repeats) on the long arm of the X chromosome. Healthy individuals have 6 to 45 CGG-repeats. The clinical manifestation of the disease is observed in the case of full mutation, which is defined as the expansion of the CGG repeat region to greater than 200 repeats.
Historical Overview
The existence of this syndrome was first described in 1943. And only 50 years later, a group of scientists discovered a gene and the effect of its mutation, which leads to the development of FraX.
In the early 20th century, geneticists from Ireland and England D. Martin and D. Bell reported a family case study in which healthy women had mentally retarded sons. They suggested that this condition was sex-linked, heritable, and caused defects in the development of the nervous system. Through their studies and research findings, the syndrome received its name. A few years later, scientists conducted a cytogenetic examination and identified a gene, which, when mutated, leads to the formation of a secondary constriction on the long arm of the X chromosome. The discovery of the first prenatal marker of the syndrome made it possible for patients to make the right decision about keeping or terminating the pregnancy.
Symptoms of Fragile X Syndrome in Boys
Decreased Muscle Tone
The first manifestation of pathology is decreased muscle tone. An overexcited or passive child does not properly respond to other people's voices and even his mother's. He develops hypo- and areflexia, which is manifested by a decrease or absence of grasping and sucking reflexes. Symptoms become more apparent over time.
Developmental Disabilities
Children with Fragile X Syndrome tend to walk and talk late. They speak at a fast, slurred rate of speech and jam words together. Fragile X speech has been described as cluttered, which is very difficult to perceive. Patients often repeat whole phrases and sentences, the same words or their endings. Some of them stutter. In severe cases, speech disorders lead to mutism, which is defined as a pathology in which a person remains completely silent.
Psychomotor Developmental
Psychomotor developmental delay is manifested when children significantly lag behind their peers. They exhibit stubborn behavior, short episodes of intense, uncontrollable anger or aggression, emotional lability, problems with focus and concentration, unreasonable fears. They often have difficulty making eye contact and tolerating touch.
Neurological Disorders
Hypermobility, Nervous Tics, Frequent Blinking, Tremors, Seizures.
Facial Features of Fragile X Syndrome
The syndrome is characterized by a distinctive facial appearance, including a large head; low-set protruding ears; abnormally tall forehead; long, narrow face; a hooked nose; a prominent chin; crossed eyes; wide palms and feet; hyperelastic and easily stretchable skin.
Intellectual Disability
The degree of mental retardation could vary from mild to severe forms. Most often, patients suffer from oligophrenia.
Congenital abnormalities of internal organs: heart defects, high-arched palate, flat feet, joint stiffness, leg deformity, foot deformities, bow legs.
The average IQ of an adult male with a full mutation is approximately 40. They show poor eye-hand coordination, memory impairment, or difficulty solving problems.
Symptoms of Fragile X Syndrome in Girls
Girls with a full mutation often have much milder symptoms than boys. They have a higher risk of emotional distress.
Girls with FXS
- Have IQ scores in the normal range or show signs of moderate mental retardation (IQ 50-69).
- On average, 35% of them have symptoms such as craniofacial changes, slowness of movement, difficulty in pronouncing certain sounds or words, or poor concentration.
However, some females with a full mutation may not show symptoms due to the selective inactivation of the abnormal X chromosome.
Diagnosis of Fragile X Syndrome
FXS can be diagnosed by testing a person's DNA from a blood test. Indications for a genetic test, which finds changes in the FMR1 gene, include:
- Patients with developmental delay, intellectual disabilities of unknown cause or autism.
- Patients with a positive family history of Fragile X.
- Patients with a positive family history of FMR1 gene.
- Families planning for a healthy pregnancy.
Based on the results of DNA diagnostics, all patients need a genetic consultation. A geneticist will correctly interpret the results and develop a plan for further treatment.
Treatment for Fragile X Syndrome
Currently there are no approved therapies for the treatment of Fragile X syndrome, a rare genetic disorder. This research study is currently enrolling children and adolescents ages 3 to 17 years of age with Fragile X syndrome.
Children are our Commitment
Learn more about a clinical trial evaluating investigational cannabidiol (CBD) gel to see if it helps behavioral issues related to Fragile X syndrome.
Qualified participants are:
- Between 3 and 17 years of age.
- Diagnosed via genetic testing, with Fragile X syndrome.
- In generally good health.
Why is this Medical Research Study Important?
The purpose of this study is to assess the efficacy and safety of cannabidiol (CBD) administered as a transdermal gel (ZYN002) for the treatment of children and adolescent patients with Fragile X syndrome (FXS).
Children and adolescents with FXS often experience behavioral symptoms such as anxiety (particularly social anxiety/avoidance), irritability, tantrums and social unresponsiveness, which can be challenging, not only for the patients, but also their families. ZYN002 may help to reduce these symptoms and has shown promising results in prior studies.
To help us learn more about the safety and efficacy of ZYN002, volunteers are needed for the RECONNECT study. Qualified participants will receive study drug or placebo and will help researchers learn if ZYN002 can help.