Review Question - QID 213712

A 2-year-old Caucasian boy is brought to urgent care with a 5-hour history of fever and cough. His parents say that he was doing well yesterday but had a fever this morning. His parents brought him in because they were worried that he is having febrile seizures. Specifically, they found him to have a few twitches throughout the morning that lasted no more than 2 seconds. Past medical history includes recurrent viral infections throughout childhood and an umbilical cord that separated about 13 days after birth. Family history is significant for a male cousin and an uncle who had an unspecified immunodeficiency. Physical exam reveals a pale blond boy with a systolic murmur best heard in the left parasternal 6th intercostal space. Which of the following would most likely be seen in this patient?