What genetic mechanism is associated with Fragile X syndrome in a patient exhibiting intellectual disability and characteristic physical features?

Fragile X syndrome is primarily caused by a specific genetic mechanism known as a trinucleotide repeat mutation on the X chromosome. This condition results from the expansion of CGG repeats in the FMR1 gene, which is located on the X chromosome. Normally, this gene has a small number of repeats, but in individuals with Fragile X syndrome, the number of repeats can increase significantly (often exceeding 200 repeats). This expansion leads to gene silencing and a subsequent lack of expression of the FMR1 protein, which is essential for normal neurological development.

Individuals with Fragile X syndrome often present with intellectual disabilities, behavioral challenges, and characteristic physical features, such as a long face, large ears, and prominent jaw. The association of these symptoms with the specific genetic mutation in the FMR1 gene underscores the importance of the trinucleotide repeat as the underlying mechanism of this condition. This genetic alteration is inherited in an X-linked manner, which accounts for the higher prevalence of symptoms in males, who are affected more severely than females due to their single X chromosome.

In summary, the trinucleotide repeat mutation on the X chromosome is the key genetic mechanism associated with Fragile X syndrome and directly correlates with the disorder's clinical presentation.