This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Genetic and genetic disorders, Subject name: Pediatrics
Which is not true about Fragile X syndrome 
Select and explain. 
A. Large testis, B. Pigmented nevi, C. Large ear present, D. Long face
B: Pigmented nevi
Answer: B: Pigmented nevi 
Explanation: Fragile X syndrome is associated with the loci Xq27.3 on the distal long arm of the X chromosome. In affected males, it is mainly characterized by mental retardation, macroorchidism, autistic behaviour, facial features like long face, large ears, prominent square jaw Pigmented naevi are not seen associated with fragile X syndrome. Reference : Nelson paediatrics 19th edition pg 411