All the statements are seen in fragile X syndrome except
**Fragile X Syndrome Basics**
Fragile X syndrome is a genetic disorder caused by a mutation in the FMR1 gene on the X chromosome, leading to the absence of the fragile X mental retardation protein (FMRP). This results in intellectual disability, behavioral problems, and physical characteristics.
**Why the Correct Answer is Right**
FMRP plays a crucial role in regulating synaptic plasticity and translation of specific mRNAs. The absence of FMRP leads to abnormal dendritic spine morphology, reduced synaptic strength, and impaired neuronal communication. This results in the characteristic cognitive and behavioral deficits seen in fragile X syndrome.
**Why Each Wrong Option is Incorrect**
**Option A:** Macroorchidism is a common feature of fragile X syndrome, particularly in post-pubertal males.
**Option B:** Fragile X syndrome is associated with a range of physical characteristics, including a long face, prominent jaw, and large ears.
**Option C:** Individuals with fragile X syndrome often exhibit anxiety, attention deficit hyperactivity disorder (ADHD), and autism spectrum disorder (ASD) symptoms.
**Clinical Pearl / High-Yield Fact**
Fragile X syndrome is the most common cause of inherited intellectual disability, affecting approximately 1 in 4,000 males and 1 in 8,000 females.
**Correct Answer: C. Individuals with fragile X syndrome often exhibit anxiety, attention deficit hyperactivity disorder (ADHD), and autism spectrum disorder (ASD) symptoms.**