White Paper 23/08: Genetic Associations with Traits in 23andMe Customers
Authors: Saniya Fayzullina Robin P. Smith Nicholas Furlotte Youna Hu David Hinds Joyce Y. Tung Created: December 4, 2014 Revised: February 25, 2015
Comments by Dean McKay, PhD:
The findings from the Fayzullina et al study of genetic features of misophonia should be interpreted with extreme caution. Specifically, there are several aspects that make the value of these findings limited. First, the effects were extremely small. The statistic in question, the odds ratio, indicates that the gene identified puts someone at 1.2 times the risk of having an aversion to chewing sounds. In terms of effects, no effect would be considered an odds ratio of 1 (having a gene puts someone at no greater risk, or 1X risk).
According to geneticists, a meaningful effect would be an odds ratio or at least 2.5 (discussed in Kendler, 2005). Second, the effect obtained is far lower than for other behaviors and attitudes that are not considered disease entities. For example, in a different GWAS, it was shown that specific genes could account for conservative or liberal political attitudes (with odds ratios over 3). This means that the genetic contribution to political ideology is over three times the effect observed for predicting aversion to chewing sounds. Third, and this is relevant to all genetic research, is that this all assumes that genes do not change. However, research has shown that environmental factors can significantly affect gene expression (see this link, for one of the early findings supporting this).
Fourth, and finally, the GWAS in question based the identification of misophonia sufferers on the basis of a single yes/no question. Is this a reasonable and robust way of identifying sufferers? It would seem unlikely based on my experience with the condition. Yes, many sufferers find chewing sounds aversive; but some individuals find other sounds aversive and are comparably unbothered by chewing. These are all very significant limitations, so please be cautious in interpreting these findings.
Genetic research may uncover important discoveries in understanding misophonia. But this particular study is not likely the one that will be groundbreaking, despite the impressive methodology and very large sample.
Dean McKay, PhD
Professor of Psychology
Editor’s note: The following articles may be of interest to readers.
For more information on epigenetics please go here.