Type XXIV collagen is a fibrillar collagen containing two collagenous domains and three noncollagenous domains. The amino-terminal peptide contains a thrombospodin-N-terminal-like motif and a highly charged segment interspersed with several tyrosine residues. Type XXIV collagen is predominately expressed in the formation of bone but to a lesser extent is also found in soft tissues such as the brain, muscle, kidneys, spleen, liver, lung, testis, and ovary. The gene COL24A1 is increased during squamous cell carcinoma of the head and neck could be a marker of osteoblast differentiation and certain types of cancers. Currently, there are no mutations in humans or mice associated with biological functions, and no biomarkers have been put forward.