Review Question - QID 216652

A 3-month-old infant is evaluated by her pediatrician during a routine check-up. Her parents report that she has been sleeping more than usual and has not been feeding well over the past few weeks. She was born to a 32-year old mother at 37 weeks gestation via an uncomplicated vaginal delivery. She was told her child was "smaller than usual." She has noticed her child is less interactive and alert when compared to other children her age. Her mother has been struggling to breastfeed her as well. On physical exam, her temperature is 97.0°F (36.1°C), blood pressure is 70/40 mmHg, pulse is 133/min, and respirations are 22/min.Physical exam is notable for conjunctival pallor. Examination of the hands is shown in Figure A. Head circumference is at the 5th percentile and weight is at the 25th percentile for age. Basic lab tests are performed with the following results:

Hemoglobin: 4.4 g/dL
Mean corpuscular volume: 111 µm^3
Reticulocytes: 0.2%
Hematocrit: 13.2%
Platelet count: 250,000/mm^3
Blood type: O-
Maternal blood type: A-

Which of the following is the most likely diagnosis?