Effects of an Asian-specific nonsynonymous EDAR variant on multiple dental traits

Abstract

Dental morphology is highly diverse among individuals and between human populations. Although it is thought that genetic factors mainly determine common dental variations, only a few such genetic factors have been identified. One study demonstrated that a nonsynonymous single-nucleotide polymorphism (370V/A, rs3827760) in the ectodysplasin A receptor gene (EDAR) is associated with shoveling and double-shoveling grades of upper first incisors and tooth crown size. Here, we examined the association of EDAR 370V/A with several dental characters in Korean and Japanese subjects. A meta-analysis that combined analyses of Korean and Japanese subjects revealed that the Asian-specific 370A allele is associated with an increase in the grades of shoveling and double shoveling, as previously found. We also showed a highly significant association between EDAR 370V/A genotype and crown size, especially mesiodistal diameters of anterior teeth. Moreover, we found that the 370A allele was associated with the presence of hypoconulids of lower second molars. These results indicated that the EDAR polymorphism is responsible, in part, for the Sinodonty and Sundadonty dichotomy in Asian populations, and clearly demonstrated that the EDAR polymorphism has pleiotropic effects on tooth morphology. As the 370A allele is known to be a most likely target of positive selection in Asian populations, some phenotypes associated with the variant may be 'hitchhiking phenotypes', while others may be actual targets of selection.

Comparative analysis of facial morphology between Okinawa Islanders and mainland Japanese using three‐dimensional images

“…In the Japanese populations, the same genetic variants may be associated with this trait. 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 (Fujimoto et al, 2008a, b;Kimura et al, 2009;Park et al, 2012;Kamberov et al, 2013;Tan et al, 2013), shows highly different frequencies between mainland Japanese and the Ryukyuans (Yamaguchi-Kabata et al, 2008). Therefore, the EDAR variant is one of the candidates possibly associated with facial characteristics differentiated between the two populations.…”

Association of common PAX9 variants with permanent tooth size variation in non-syndromic East Asian populations

“…As described in a previous report, 26 plaster casts of permanent dentition and blood, buccal mucosa or saliva specimens for DNA preparation were obtained from 223 Korean individuals at Pusan National University, Pusan, and from 273 Japanese individuals at Showa University Dental Hospital, Tokyo. The Korean subjects were 130 male and 93 female healthy individuals with 20-40 years of age (mean: 28.1).…”

“…26 In the Korean and Japanese subjects, the mesiodistal (MD) and buccolingual (BL) crown diameters of upper (U) and lower (L) teeth, that is, 1st and 2nd incisors (I1 and I2), canines (C), 1st and 2nd premolars (P1 and P2), and 1st and 2nd molars (M1 and M2), except for M3, were measured with a sliding caliper. The geometric mean (GM) of the MD and BL diameters was calculated for each tooth and used as an index of crown size.…”

“…We also evaluated 10 non-metric dental traits (shoveling and double shoveling in UI1, tuberculum in UI1, UI2 and UC, hypocone in UM2, Carabelli's cusp in UM1 and UM2, and hypoconulid and groove pattern in LM2), as previously reported. 26 …”

“…24 The genetic origins of common dental variations, unlike those of dental anomalies, are poorly understood. While a common nonsynonymous variant in EDAR (Val370Ala) is associated with normal variation in dental traits, such as crown size, shoveling and double shoveling of incisors, 25,26 this EDAR polymorphism alone cannot account for the degree of heritability of such dental traits. Common variations in dental traits are thought to be controlled by multiple factors.…”