Stephania and Nikolaus Stamos are concerned about their baby daughter. They take her to her pediatrician, who immediately notices that the once bright and active child is small for her age, pale, lethargic, and has a swollen abdomen. Students examine the patient's symptoms and test results, and then construct a pedigree chart and Punnett square to identify and understand the genetic disorder she is suffering from. Originally developed for a molecular biology course taken mostly by junior and senior undergraduate students, the case can be adapted for use in a course in cell biology, physiology, biochemistry, or genetics (see also the related "Physiology Edition").