C18orf22, also known as HsT169, is a 343 amino acid protein that localizes to the mitochondrion and is expressed as two alternatively spliced isoforms that are encoded by a gene which maps to human chromosome 18. Chromosome 18 houses over 300 protein-coding genes and contains nearly 76 million nucleotide bases. There are a variety of diseases associated with defects in chromosome 18-localized genes, some of which include Trisomy 18 (also known as Edwards syndrome), Niemann-Pick disease, hereditary hemorrhagic telangiectasia, erythropoietic protoporphyria and follicular lymphomas.