Q. A 6-month-old male infant presents to the pediatric clinic with concerns of recurrent infections. His mother reports that he has been frequently ill since birth, with multiple episodes of pneumonia, otitis media, and diarrhea. She has also noted that he has difficulty feeding. On physical examination, the patient is found to have dysmorphic facial features, including a small chin and widely spaced eyes. His ears are low set and malformed. Examination of his cardiovascular system reveals a murmur. Laboratory investigations revealed low levels of parathyroid hormone. You refer the patient to a geneticist for further evaluation. A CT scan of his brain demonstrates basal ganglia and periventricular calcifications (see image). After a thorough evaluation and genetic testing, a diagnosis of DiGeorge syndrome is made. Which of the following additional disorders would you LEAST expect to find in this patient?