Fragile X Syndrome (FXS) is caused by a mutation in the FMR1 gene, which is located on the X chromosome. This gene is responsible for producing the Fragile X Mental Retardation Protein (FMRP). FMRP plays a crucial role in the development of synapses, which are the connections between neurons in the brain. It is involved in regulating the production of proteins at synapses in response to neuronal activity and is important for learning and memory.
The mutation in the FMR1 gene that leads to FXS is a trinucleotide repeat expansion. Normally, the CGG sequence is repeated 5 to 40 times in the gene. In individuals with FXS, however, this sequence is repeated more than 200 times, leading to what is known as a full mutation. This expansion causes the gene to become methylated, a chemical modification that effectively silences the gene's expression. As a result, the production of FMRP is either significantly reduced or completely absent.
The lack or reduced levels of FMRP in individuals with FXS lead to various developmental problems, including intellectual disability, behavioral challenges, and characteristic physical features. The protein's absence disrupts the normal regulation of synaptic development and neuronal signaling, contributing to the cognitive deficits and learning disabilities associated with the condition.
Problem:
What is the consequence of the FMR1 gene mutation in Fragile X Syndrome?
A) Overproduction of the FMRP protein
B) Prion-like protein aggregation in neurons
C) Production of a truncated, non-functional FMRP protein
D) Reduced production or absence of the FMRP protein
