Earlobe Attachment Characteristic Involves at Least 49 Genes, University of Pittsburgh-Led Study Including 23andMe Data Shows

A common, hands-on method for teaching genetics in grade school encourages students to compare their earlobes with those of their parents: Are they attached and smoothly mesh with the jawline? Or are they detached and dangly? The answer is meant to teach students about dominant and recessive genes. Simple, right? Not so fast. New research led by the University of Pittsburgh (Pitt) Graduate School of Public Health and School of Dental Medicine, and published online on November 30, 2017 in the American Journal of Human Genetics, reveals that the lesson is much more complicated, with an interplay of at least 49 genes contributing to earlobe attachment. "Sometimes the genetics of a fairly simple trait are actually quite complex," said lead author John R. Shaffer, Ph.D., Assistant Professor in Pitt Public Health's Department of Human Genetics and the Department of Oral Biology in Pitt's School of Dental Medicine. "By understanding that complexity, we can work toward treatments for genetic conditions, several of which have distinct facial features that involve the earlobe, including Mowat-Wilson Syndrome, which can cause cupped ears with protruding lobes." The study was an international collaboration involving investigators in the United Kingdom and China, and included data from the U.S.-based personal genetics company 23andMe Inc. "The great thing about these collaborations is that we not only had a large sample size, but we also had participants from different ethnicities, giving us a greater depth of genetic information," said senior author Seth M. Weinberg, PhD, Associate Professor in Pitt's Departments of Oral Biology and Human Genetics. The open-access AJHG article is titled “Multiethnic GWAS Reveals Polygenic Architecture of Earlobe Attachment.”
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