Proximal symphalangism, or Cushing symphalangism (MIM 185800), is an autosomal dominant disorder characterized by ankylosis of the proximal interphalangeal joints. Conductive deafness and reduced flexibility of the ankles have also been observed in affected individuals. We have used polymorphic markers throughout the genome to perform genetic linkage analysis in subsequent generations of the family originally described by Harvey Cushing. We have established linkage for this disorder to markers on chromosome 17 (17q21-q22), with Zmax = 6.98 at theta = 0.05 with marker D17S790.