Exploring the Presence of the Catechol-O-Methyltransferase (COMT) Polymorphism in Marmosets and its Potential Influence on Prosocial Behavior

Abstract

The Catechol-O-Methyltransferase gene (COMT) is an important gene involved in the enzymatic breakdown of the neurotransmitter dopamine. In humans, there is a functional single-nucleotide polymorphism (SNP) (rs4680) where a Valine (GTG) is substituted for a Methionine (ATG) resulting in lower COMT enzyme activity in the catabolism of dopamine. This leads to increased biologically-available dopamine in brain synapses. However, no information is currently available as to whether this functional COMT SNP is present in the Platyrrhini parvorder or more specifically the Cebidae family including marmosets and tamarins. Using nested polymerase-chain-reaction (PCR) we amplified extracted DNA from four species of marmosets (Callithrix sp.) and one species of tamarin (Leontopithecus rosalia), sequenced the DNA for the presence of the rs4680 SNP, and aligned the sequence data to reference primates. We found no evidence of the rs4680 SNP in marmosets and tamarins, which likely indicates very low or absent allelic variation in the rs4680 SNP. We did find the presence of a novel SNP located in AA position 369 in the COMT gene. This nucleotide substitution from T to C leads to a synonymous protein product likely suggesting no functional impact. The allelic frequency of this SNP in the sampled population is TT = 14.3%, TC = 17.9%, and CC = 67.9%. More sampling of Platyrrhini (New-World monkeys) and other mammals is required, but these data, as they currently stand, suggest the rs4680 mutation likely occurred after the emergence of Catarrhini (Old-World monkeys, Great Apes, human lineages) which occurred approximately 20-38 million years ago