- Thrombocytosis (HP:0001894): Increased numbers of platelets in the peripheral blood. Evidence: TAS. Frequency: Occasional (HP:0040283). (OMIM:271400)
- Howell-Jolly bodies (HP:0032550): Howell-Jolly bodies are small, intra-erythrocytic remnants of erythrocyte nuclei. These inclusions are solitary in each erythrocyte and strongly basophilic. These are often confused with overlying platelets, but can be distinguished by the presence of a halo around overlying platelets. Evidence: PCS. (PMID:12111187)
- Infantile onset (HP:0003593): Onset of signs or symptoms of disease between 28 days to one year of life. Evidence: TAS. (OMIM:271400)
- Asplenia (HP:0001746): Absence (aplasia) of the spleen. Evidence: TAS. (OMIM:271400)
- 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:271400)
These phenotypes are associated with the disease familial isolated congenital asplenia (OMIM:271400).