Question

True about Fragile X syndrome is

• A. Triple nucleotide CAG Sequence mutation
• B. 10% Female carriers mentally retarded
• C. Males have IQ 20-40
• D. Gain of function mutation

Answer 1

The Correct Option is C

Fragile X syndrome is a genetic condition with several key characteristics:

• The correct statement about Fragile X syndrome is that males suffering from this condition typically have an IQ ranging from 20 to 40. This range indicates a moderate to severe intellectual disability, which is a prominent feature of the disorder.
• The syndrome is caused by a mutation in the FMR1 gene on the X chromosome, but it is not specifically a CAG repeat mutation; instead, it involves a CGG triplet repeat expansion.
• Female carriers of the Fragile X gene mutation may show milder intellectual deficits, but about 50% of them might have some form of cognitive or emotional issue, not specifically 10% being mentally retarded, as female carriers are less severely affected due to X-inactivation.
• The mutation in Fragile X syndrome is typically a loss of function mutation due to the silencing of the FMR1 gene from the expansion of CGG repeats, leading to the absence or reduction of the FMRP protein, which is essential for normal neural development.