Subsection of human phenotype ontology (HPO). Terms at left illustrate the ontology’s hierarchical arrangement. The numbers in parentheses indicate the number of genes that term directly annotates. A term is considered to annotate a gene if it directly annotates the gene, as shown in figure, or if it indirectly annotates the gene through any of its descendants, e.g. “Abnormality Higher Mental Function” is considered to annotate all 235 genes annotated by “Cognitive Impairment”. The gene list to the right illustrates how HPO terms are annotated to genes. The numbers in parentheses indicate the total number of HPO terms that directly annotate the gene.