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: Medicine
Stiff person syndrome is associated with: 
Select and explain. 
A. Anti GAD, B. Anti Amphiphysin, C. Both of the above, D. None of the above
C: Both of the above
Answer: C: Both of the above 
Explanation: This disorder is characterized by progressive muscle rigidity, stiffness, and painful spasms triggered by auditory, sensory, or emotional stimuli. Rigidity mainly involves the lower trunk and legs, but it can affect the upper extremities and neck. Symptoms improve with sleep and general anesthetics. Electrophysiologic studies demonstrate continuous motor unit activity. Antibodies associated with the stiff-person syndrome target proteins involved in the function of inhibitory synapses utilizing -aminobutyric acid (GABA) or glycine as neurotransmitters. Ref: Harrison's principle of internal medicine 17th edition, chapter 97.