- Reduced factor VIII activity (HP:0003125): Reduced activity of coagulation factor VIII. Factor VIII (fVIII) is a cofactor in the intrinsic clotting cascade that is activated to fVIIIa in the presence of minute quantities of thrombin. fVIIIa acts as a receptor, for factors IXa and X. Evidence: TAS. (OMIM:134510)
- Reduced factor IX activity (HP:0011858): Decreased activity of coagulation factor IX. Factor IX, which itself is activated by factor Xa or factor VIIa to form factor IXa, activates factor X into factor Xa. Evidence: TAS. (OMIM:134510)
- 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:134510)
These phenotypes are associated with the disease factor VIII and Factor IX, combined deficiency of (OMIM:134510).