COMMD9 (COMM domain containing 9) is a 198 amino acid ubiquitously expressed protein that contains one COMM domain and may be involved in signaling events throughout the cell. The gene encoding COMMD9 maps to human chromosome 11, which houses over 1,400 genes and comprises nearly 4% of the human genome. Jervell and Lange-Nielsen syndrome, Jacobsen syndrome, Niemann-Pick disease, hereditary angioedema and Smith-Lemli-Opitz syndrome are associated with defects in genes that maps to chromosome 11.