Quantitative genetics of monoamine metabolites in pedigreed baboons, papio hamadryas

The monoamine neurotransmitters serotonin, dopamine and norepinephrine are related to a number of fundamental neurophysiological processes, as well as to psychiatric diseases such as depression, anxiety disorders, bipolar disorder and risk of suicide. While it is clear that genetic variation among people influences levels of neurotransmitters found in the cerebrospinal fluid, the details of this genetic control are not understood. In an effort to learn more about the genetics of monoamine levels, we measured levels of metabolites for these monoamines (5-HIAA, HVA and MHPG) in 270 pedigreed baboons. All study animals can be linked into a single large pedigree, providing unique opportunities to examine quantitative genetic parameters. All three compounds exhibit significant heritability (5-HIAA h2 = 0.30, HVA h2 = 0.50, MHPG h2 = 0.36). Bivariate genetic correlations calculated using variance components methods reveal that the genetic correlation between MHPG and HVA is rho = 0.91, indicating that 83% of the genetic variance is shared between these two traits. In addition, it has long been known that HVA and 5-HIAA are phenotypically correlated in humans. Our results show that in baboons the genetic correlation is 0.50 and environmental correlation 0.71, both statistically significant. This means the common phenotypic correlation of HVA and 5-HIAA is due both to shared genes and shared environmental effects. A genome scan is planned to locate specific loci controlling monoamine levels in the baboons.