As these GEITP pages have often described, the genetic basis of variability in any disease phenotype, in a quantitative phenotype such as height or body mass index, or in response to a drug or an environmental toxicant can be grouped into three categories: (a) monogenic (Mendelian) traits that typically represent one or a few rare coding variants; (b) predominantly oligogenic traits that represent variability contributed by a small number of major genes; and (c) multifactorial traits –– produced mostly by numerous small-effect variants, together with epigenetic effects and environmental factors. EMPATHY is the ability to perceive other people’s thoughts, intentions, desires, and feelings –– and to respond to others’ mental states with an appropriate emotion. Obviously, DEGREE OF EMPATHY (if it can be quantitated at all) would fall into the category of multifactorial traits. Authors of the attached paper attempt to answer three questions: (a) what is the polygenic architecture of empathy? (b) Is empathy genetically correlated with various psychiatric conditions, psychological traits, and/or education? (c) Is there a genetic contribution to sex differences in empathy?
Authors performed gender-stratified and non-stratified genome-wide association study (GWAS) analyses of empathy in research participants from 23andMe (a personalized genetics company). They calculated the narrow-sense heritability explained by all the single-nucleotide polymorphisms (SNPs) tested, and investigated sex differences. Finally, they conducted genetic correlation analyses with six psychiatric conditions –– anorexia nervosa, attention deficit hyperactivity disorder (ADHD), autism spectrum disorder (ASD), bipolar disorder, major depressive disorder, and schizophrenia –– as well as psychological traits, and level of education attained.
This report represents the largest GWAS of empathy to date –– using a well-validated self-report measure of empathy, the Empathy Quotient (EQ), in 46,861 research participants from 23andMe, Inc. Authors identified 11 suggestive SNPs (P <1 × 10–6), although none were significant at P < 2.5 × 10–8 after correcting for multiple-testing. The most significant SNP was identified as an intronic SNP in the gene encoding transmembrane protein-132C (TMEM132C). As predicted, based on earlier work, authors confirmed a significant female advantage on the EQ (P <2 × 10–16). Authors identified similar SNP heritability and high genetic correlation between the sexes, suggesting the same genes are involved in empathy for both sexes. Also, as predicted, authors identified a significant negative genetic correlation between autism and the EQ (P = 1.63 × 10–4). Authors also identified significant positive genetic correlations between the EQ and risk for schizophrenia, anorexia nervosa, and extrovert behavior. This intriguing study represents the first GWAS of self-reported empathy. These data suggest that the genetic variations associated with empathy also play a role in certain psychiatric conditions and psychological traits. Translational Psychiatry 2018; 8: 35