Human genetic disease is greatly influenced by the underlying fragility of evolutionarily ancient genes

The ability to predict disease association in human genes is enhanced by an evolutionary understanding. Importantly genes linked with heritable disease, particularly dominant disorders, tend to have undergone duplication in our early vertebrate ancestors, with a strong asymmetric relationship between disease-association within duplicate/paralog pairs. Using a novel phylogenetic approach, alongside a whole-genome comparative analysis, we show that contrary to the accepted compensatory model of disease evolution, the majority of disease-associations reside with the more evolutionary constrained gene, inferred to most closely resemble the progenitor. This indicates that the strong association between paralogs, specifically ohnologs, and dominant disorders is often a consequence of a mechanism through which pre-existing dosage sensitive/haploinsufficient genes are successfully duplicated and retained. Heritable disease is thus as much a consequence of the fragility of evolutionarily more ancient genes as compensatory mechanisms. From these findings, we demonstrate the utility of a new model with which to predict disease associated genes in the human genome.