This gene is a member of the transferrin gene family. Unlike many members of that gene family it does not play a significant role in iron homeostasis but rather is an inhibitor of carbonic anhydrase. This gene arose as a tandem duplicate of the adjacent transferrin gene sometime after the divergence of monotremes and therian mammals but before the diversification of placental mammals. This gene subsequently became a pseudogene in monkeys and apes. In lemurs and other strepsirrhine primates it possibly remains a protein coding gene. [provided by RefSeq, Oct 2021]