A tired young man with a dysmorphic thumb

A 23 year old man with short stature, congenital malformation of the left thumb and both ears, and a single kidney presented with back pain, shortness of breath, fatigue, and easy bruising that had developed over several months. Physical examination revealed hepatosplenomegaly. His brother had died in early childhood, more than 20 years ago. The patient’s parents reported that his brother, “had similar but worse congenital malformations,...