Fragile x syndrome

Fragile X Syndrome

Fragile X Syndrome (FXS) is a genetic disorder that is a leading cause of inherited intellectual disability and autism. It is caused by a mutation in the FMR1 gene located on the X chromosome. This mutation leads to a deficiency or absence of the fragile X mental retardation protein (FMRP), which is crucial for normal neural development.

Genetics

Fragile X Syndrome is an X-linked dominant condition. The FMR1 gene contains a region of CGG trinucleotide repeats. In individuals with FXS, this region is expanded to over 200 repeats, leading to methylation and silencing of the gene. This results in the lack of production of FMRP, which is necessary for synaptic function and plasticity.

Inheritance

FXS is inherited in an X-linked dominant pattern. Males are typically more severely affected than females because they have only one X chromosome. Females have two X chromosomes, so they may have a second, normal copy of the FMR1 gene that can partially compensate for the defective one.

Symptoms

The symptoms of Fragile X Syndrome can vary widely among individuals but often include:

• Intellectual disability: Ranging from mild to severe.
• Behavioral characteristics: Including attention deficit, hyperactivity, anxiety, and autistic behaviors.
• Physical features: Such as a long face, large ears, and a prominent jaw.
• Speech and language delays: Often present in affected individuals.

Diagnosis

Diagnosis of Fragile X Syndrome is confirmed through genetic testing, which identifies the CGG repeat expansion in the FMR1 gene. Prenatal testing is also available for at-risk pregnancies.

Management

There is currently no cure for Fragile X Syndrome, but various interventions can help manage symptoms:

• Educational support: Tailored educational programs and therapies.
• Behavioral therapy: To address behavioral issues and improve social skills.
• Medications: To manage symptoms such as anxiety, ADHD, and mood instability.

Research

Ongoing research is focused on understanding the molecular mechanisms of FXS and developing targeted therapies. Studies are exploring the use of drugs that can modulate synaptic function and plasticity.

Also see

• X-linked dominant inheritance
• Intellectual disability
• Autism spectrum disorder
• Genetic testing