Enhanced ectodysplasin-A receptor (EDAR) signaling alters multiple fiber characteristics to produce the East Asian hair form

The study from 2008 investigated the role of the ectodysplasin-A receptor (EDAR) in the development of the characteristic hair form found in East Asian populations. The researchers focused on a single nucleotide polymorphism (SNP), rs3827760, which leads to a variant known as EDAR370A, prevalent in East Asian and Native American populations but almost absent in European and African groups. They found that this variant results in more potent signaling output than the ancestral form of the receptor. In transgenic mice, increased EDAR activity led to hair characteristics similar to those of East Asians, including coarser texture, straightening, thickening of individual hairs, and a circular cross-sectional profile. These changes were due to enlarged hair follicles, which originated from larger embryonic organ primordia. The study concluded that simple genetic alterations in the EDAR gene could explain the distinct hair morphology differences between East Asian populations and others.