This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Genetics, Subject name: Medicine
Diabetes mellitus is present in all except 
Select and explain. 
A. Fanconi syndrome, B. Noonan syndrome, C. Ataxia telengiectasia, D. Myotonic dystrophy
B: Noonan syndrome
Answer: B: Noonan syndrome 
Explanation: The disorder is characterized by progressively impaired coordination of voluntary movements (ataxia), the development of reddish lesions of the skin and mucous membranes due to permanent widening of groups of blood vessels (telangiectasia), and impaired functioning of the immune system (i.e., cellular and humoral) Ref Robbins 9/e pg 243