Symphalangism, Distal

Description

Distal symphalangism is ankylosis or rigidity of the distal interphalangeal joints of the hands and/or the feet (summary by Poush, 1991).

Clinical Features

Inman (1924) found distal symphalangism in 4 generations of a family. In the published x-rays, the fusion was most complete in the index finger. Steinberg and Reynolds (1948) provided follow-up on the family of Inman (1924).

Cole (1935) described fused distal interphalangeal joint of the index finger only, behaving apparently as an irregular dominant. There were skipped generations.

Matthews et al. (1987) described 5 affected persons in 4 generations of a family with male-to-male transmission. The thumbs and great toes were also affected, a feature not previously noted in distal symphalangism.

Poush (1988, 1991) observed a multigenerational family with this trait. The index finger was predominantly affected, and the toes were also affected in most subjects. Some individuals had absence or hypoplasia of fingernails or toenails. This family may be related to the family reported by Inman (1924). Prepubertal x-rays showed a nonossified space and no distal phalanx growth plate in the index finger. One individual with severe involvement of the distal interphalangeal joints was born with craniosynostosis involving the sagittal suture and craniofacial asymmetry. Poush (1991) also described a smaller family, which was apparently unrelated to the first, although it lived in the same geographic area.

Inheritance

The pedigree pattern in several reported families with distal symphalangism (e.g., Inman, 1924; Cole, 1935; Matthews et al., 1987; Poush, 1991) is consistent with autosomal dominant inheritance.