SKI and Shprintzen-Goldberg syndrome: Shprintzen-Goldberg syndrome (SGS) is a human disorder characterized by craniofacial, cardiovascular, neuromuscular, and skeletal anomalies.290,291 The specific mutation consists of an in-frame deletion in exon 1 of the human Ski gene; this mutation falls within the Ski protein region of interaction with R-Smad.290–292 Thus, SGS alterations correlate with uncontrolled TGF-β signaling activation since mutant Ski cannot bind Smad proteins.