A new study by the University of Pittsburgh has identified 49 genes involved in the formation of the external ear.

The largest study to date, using over 75,000 multi-ethnic samples, could identify potential treatment for genetic conditions such as Mowat-Wilson syndrome.Their findings are described in the American Journal of Human Genetics.

(Credit: UPMC) 

Attached earlobes versus free (with a loose or hanging lobe) have often be used to illustrate basic genetics. The myth being that earlobes can be divided into these two clear categories and that a single gene controlled the trait.

Using observations and genomic data from 10,000 study participants from three ethnic groups – European American, Latin American and Chinese, the team at UP supplemented these with self-reporting from 65,000 customers of 23andme with European ancestry. 

“Sometimes the genetics of a fairly simple trait are actually quite complex,” first author John Shaffer from Pitt says.

As expected, rates of lobe attachment differed across the ethnic groups and the study initially identified 6 dominant loci associated with rates of earlobe attachment. Additional meta-analysis across the four groups yielded a further 43 significant associations.

Ear malformations are significant not only for cosmetic and hearing issues but can also be associated with kidney disorders, muscular-facial and dental issues as these develop in the foetus during the same stage. 

Understanding the level of complexity involved in the formation of the human ear could identify pathways to potential treatments for conditions such as Agnathia-otocephaly, and Mowat-Wilson Syndrome.