- Autosomal dominant inheritance (HP:0000006): A mode of inheritance that is observed for traits related to a gene encoded on one of the autosomes (i.e., the human chromosomes 1-22) in which a trait manifests in heterozygotes. In the context of medical genetics, an autosomal dominant disorder is caused when a single copy of the mutant allele is present. Males and females are affected equally, and can both transmit the disorder with a risk of 50% for each child of inheriting the mutant allele. Evidence: TAS. (OMIM:185650)
- Synostosis involving the 1st metacarpal (HP:0009703): Fusion of the 1st metacarpal with another bone. In contrast to the proximal phalanges of the digits 2 to 5, the proximal phalanx of the thumb is embryologically equivalent to the middle phalanges of the other digits, whereas the first metacarpal is embryologically of phalangeal origin and as such equivalent to the proximal phalanges of the other digits. Evidence: TAS. (OMIM:185650)
These phenotypes are associated with the disease symphalangism, C. S. Lewis type (OMIM:185650).