NOG and brachydactyly type B2: Subsequent genetic studies demonstrated that NOG gene mutations cause several bone disorders such as stapes ankylosis with broad thumbs and toes (SABTT), proximal symphalangism (SYM1), multiple synostoses syndrome 1 (SYNS1), tarsal–carpal coalition syndrome (TCC), and brachydactyly type B2 (BDB2) [9,17].