A 30-hour-old boy develops jaundice and pallor. He is feeding reasonably well and has mild splenomegaly. His mother is blood group O positive and he is group B positive; the direct antiglobulin test is negative. The blood film shows numerous spherocytes, and the mean corpuscular haemoglobin concentration is increased. His father reports having required removal of his spleen as a young adult for recurrent anaemia. Which one of the following is the most likely diagnosis?