[1] After graduating, he returned to New York City to complete a rotating internship and a residency in pediatrics at Queens General Hospital.
[2] Dancis was appointed as an academic in the Bellevue Hospital pediatrics department led by L. Emmett Holt Jr.
[2] He noticed that none of the staff members at Bellevue were particularly interested in neonatology, or study of the newborn, and so decided to "fill the vacuum" himself.
[1] He made significant contributions to the research of inborn errors of metabolism; this included identifying with colleagues the enzyme defect that causes maple syrup urine disease.
On the day that he died, he had attended the pediatrics grand rounds at NYU before collapsing while walking home to his apartment.