This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: None, Subject name: Pathology
All are true about Fragile X syndrome except ? 
Select and explain. 
A. Large'head, B. Large nose, C. Large ear, D. Large testis
B: Large nose
Answer: B: Large nose 
Explanation: Ans. is 'b' i.e., Large nose Fragile - X syndrome o Fragile - X syndrome is the prototype of diseases in which the mutation is characterized by a long repeating sequence of three nucleotides. In fragile X syndrome,trinucleotide repeat mutation involve CGG on non coding region. o Clinical features of fragile - X syndrome Mental retardation Long face with large mandible q Hyperexntesible joint q Mitral valve prolapse Large eveed ears Large testis (macro-orchidism) q High arched palate o Fragile X syndrome is the second most common cause of mental retardation, after Downs syndrome.