An autosomal dominant condition caused by pathogenic variants of the NOG gene, encoding the noggin protein. Five overlapping clinical syndromes associated with NOG mutations have been described; proximal symphalangism, multiple synostoses syndrome 1, tarsal-carpal coalition syndrome, stapes ankylosis with broad thumbs and toes, and brachydactyly type B2. NOG-related symphalangism spectrum disorder is a new term initially proposed by Potti et al., 2011 to encompass these disorders. NOG-SSD is characterized by proximal symphalangism, conductive deafness caused by stapes ankylosis, ocular abnormality such as hyperopia and strabismus, and characteristic facial features including a broad, tubular-shaped nose and a thin upper vermilion.