Final answer:
Fragile X syndrome is a genetic disorder caused by a mutation in the FMR1 gene, characterized by intellectual disability and distinct physical features. The mutation involves an excess of CGG repeats leading to gene silencing. Treatments aim to manage symptoms, and genetic counseling is advised for affected families.
Step-by-step explanation:
Fragile X syndrome (FXS) is a genetic disorder caused by a mutation in the FMR1 gene located on the X chromosome. It is passed down in an X-linked dominant inheritance pattern. The mutation involves a segment of DNA that has a series of CGG repeats; in affected individuals, the number of these repeats increases significantly, often exceeding 200 repetitions (normal being up to 44 repeats). This expansion leads to methylation and silencing of the gene, preventing the production of the FMRP protein which is crucial for normal neural development.
FXS is the most common form of inherited intellectual disability and can cause a range of developmental problems including learning disabilities and cognitive impairment. Physical features may include a long face, large ears, and flexible fingers. Behavioral characteristics might involve autism spectrum disorders and attention difficulties. Diagnosis is confirmed through genetic testing that identifies the FMR1 mutation.
There is no cure for Fragile X syndrome, but treatments focus on managing symptoms, including educational interventions, medication to control mood and behavior, and various forms of therapy. Genetic counseling is recommended for families affected by FXS to understand the inheritance pattern and implications for future pregnancies.