USMLE® Step 1 style questions USMLE
A 3-year-old boy is brought to the clinic by his mother, who is concerned about the appearance of his legs. She has noticed that his knees tend to point outwards and that he is not meeting his age-related goals for height. He was breastfed up until 2 months ago, and did not take any dietary supplements throughout his infancy. On examination, he is in the 5th percentile for height and there is a marked varus deformity in the lower limbs. An X-ray of the legs is ordered and shown below. Which of the following is the most likely cause of this patient's condition?