What are patients with Fragile X syndrome likely to exhibit in terms of genetic mutations?

Patients with Fragile X syndrome commonly exhibit an expansion of trinucleotide repeats, specifically in the FMR1 gene. This genetic alteration is characterized by a greater number of CGG (cytosine-guanine-guanine) repeats than is typically found in the general population. The normal range of CGG repeats is between 5 to 44, but in individuals with Fragile X syndrome, this can expand to over 200 repeats, leading to methylation of the FMR1 gene and subsequent loss of function.

This expansion interrupts normal gene function, which is critical for brain development and synaptic function, resulting in the cognitive and behavioral features associated with Fragile X syndrome. Notably, the effects of these expanded repeats can cause varying degrees of intellectual disability and developmental delays.

The other potential genetic mutation types mentioned – such as point mutations, duplications, or deletions – do not characterize Fragile X syndrome. The fundamental mechanism behind this condition is clearly tied to the repeat expansion phenomenon, making it the defining genetic characteristic of the syndrome.