TGFBR2 and Loeys-Dietz syndrome: The Loeys-Dietz syndrome is caused by a mutation in the transforming growth factor β (TGF-β) type II receptor TGFBR2 or type I receptor TGFBR1. More than 50 different mutations in TGFBR2 or TGFBR1 have been described in LDS patients.