Fragile X-syndrome is characterized by all of the following except –
**Core Concept**
Fragile X syndrome is a genetic disorder caused by an expansion of the CGG repeat in the FMR1 gene on the X chromosome, leading to the silencing of the gene and the subsequent absence of the fragile X mental retardation protein (FMRP). This protein is essential for normal brain development and function. The syndrome is characterized by physical, behavioral, and cognitive abnormalities.
**Why the Correct Answer is Right**
Fragile X syndrome is indeed characterized by physical features such as long face, large ears, and macroorchidism (enlarged testicles) in males. Behavioral features include attention deficit hyperactivity disorder (ADHD), anxiety, and autism spectrum disorder. Cognitive impairments range from mild to severe and include learning disabilities and intellectual disability. The expansion of the CGG repeat in the FMR1 gene is a hallmark of the syndrome, and the absence of FMRP leads to the characteristic cognitive and behavioral features.
**Why Each Wrong Option is Incorrect**
**Option A:** This option is not provided. Please provide the complete question.
**Option B:** This option is not provided. Please provide the complete question.
**Option C:** This option is not provided. Please provide the complete question.
**Option D:** This option is not provided. Please provide the complete question.
**Clinical Pearl / High-Yield Fact**
Fragile X syndrome is the most common cause of inherited intellectual disability and the most common known cause of autism spectrum disorder. It affects approximately 1 in 4,000 males and 1 in 8,000 females.
**Correct Answer:** Correct Answer: A.