This information is provided by the National Institutes of Health (NIH) Genetic and Rare Diseases Information Center (GARD).
Proximal symphalangism, which is also called Cushing’s symphalangism, is a rare genetic condition characterized by the fusion of the proximal joints in the hands and feet. These individuals usually have straight fingers and are unable to make a fist. Other joints may also be affected, leading to stiff joints in the elbows, ankles and wrists. Hearing loss due to the fusion of the auditory ossicles (bones in the middle ear) is also a characteristic feature. This condition is inherited in an autosomal dominant pattern and is caused by a mutation in the NOG gene or GDF5 gene.
For more information, visit GARD.