<P> Relaxin receptors have been found in the heart, smooth muscle, the connective tissue, and central and autonomous nervous system . </P> <P> Specific disorders related to relaxin have not been described, yet a link to scleroderma and fibromyalgia has been suggested . </P> <P> A recombinant form of human relaxin - 2 has been developed as investigational drug RLX030 (serelaxin). </P> <P> Relaxin 1 and Relaxin 2 arose from the duplication of a proto - RLN gene between 44.2 and 29.6 million years ago in the last common ancestor of catarrhine primates . The duplication that led to RLN1 and RLN2 is thought to have been a result of positive selection and convergent evolution at the nucleotide level between the relaxin gene in New World monkeys and the RLN1 gene in apes . As a result, Old World monkeys, a group that includes the subfamilies colobines and cercopithecines, have lost the RLN1 paralog, but apes have retained both the RLN1 and the RLN2 genes; Lawrence and Cords, 2012). </P>

What is relaxin and what does it do