Review Question - QID 104572

A three-day-old, full-term infant born by uncomplicated vaginal delivery is brought to a pediatrician by his mother, who notes that her son's skin appears yellow. She reports that the child cries several times per day, but sleeps 7-8 hours at night, uninterrupted. She has been breastfeeding the infant but feels the latch has been poor and is unsure how much milk he has been consuming but feels it is not enough. A lactation consult was called for the patient and it was noted that despite proper instruction the observed latch was still poor. When asked the mother stated that the baby is currently making stools 2 times per day. Which of the following is the most likely etiology of the patient's presentation?