This is a 3 year old boy with a history of nephrolithiasis who bites himself; his lower lip is mutilated and he has a wound on the dorsum of his hand. His tongue is spared. He has uncontrolled motor movements with action dystonia and baseline hypotonia. He also has delayed developmental milestones and mental retardation. Labs show a macrocytic anemia.
Challenge: What is this disorder? How is it inherited?
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