Review Question - QID 212879

A 9-year-old boy is admitted to the hospital for placement of halo gravitational traction in order to treat his previously observed kyphoscoliosis. Specifically, he has a previously diagnosed curve that has gotten worse over time and now threatens to compromise his thoracic cavity. His past medical history is significant for short stature, and he has consistently been below the 5th percentile for height since birth. On physical exam, he is found to have macrocephaly with frontal bossing, short arms and legs with disproportionate shortening of the proximal segments, and lumbar lordosis. Which of the following proteins are most likely mutated in this patient?