A common variation in EDAR is a genetic determinant of shovel-shaped incisors - PubMed (original) (raw)

doi: 10.1016/j.ajhg.2009.09.006.

Tetsutaro Yamaguchi, Mayako Takeda, Osamu Kondo, Takashi Toma, Kuniaki Haneji, Tsunehiko Hanihara, Hirotaka Matsukusa, Shoji Kawamura, Koutaro Maki, Motoki Osawa, Hajime Ishida, Hiroki Oota

Affiliations

A common variation in EDAR is a genetic determinant of shovel-shaped incisors

Ryosuke Kimura et al. Am J Hum Genet. 2009 Oct.

Abstract

Shovel shape of upper incisors is a common characteristic in Asian and Native American populations but is rare or absent in African and European populations. Like other common dental traits, genetic polymorphisms involved in the tooth shoveling have not yet been clarified. In ectodysplasin A receptor (EDAR), where dysfunctional mutations cause hypohidrotic ectodermal dysplasia, there is a nonsynonymous-derived variant, 1540C (rs3827760), that has a geographic distribution similar to that of the tooth shoveling. This allele has been recently reported to be associated with Asian-specific hair thickness. We aimed to clarify whether EDAR 1540C is also associated with dental morphology. For this purpose, we measured crown diameters and tooth-shoveling grades and analyzed the correlations between the dental traits and EDAR genotypes in two Japanese populations, inhabitants around Tokyo and in Sakishima Islands. The number of EDAR 1540C alleles in an individual was strongly correlated with the tooth-shoveling grade (p = 7.7 x 10(-10)). The effect of the allele was additive and explained 18.9% of the total variance in the shoveling grade, which corresponds to about one-fourth of the heritability of the trait reported previously. For data reduction of individual-level metric data, we applied a principal-component analysis, which yielded PC1-4, corresponding to four patterns of tooth size; this result implies that multiple factors are involved in dental morphology. The 1540C allele also significantly affected PC1 (p = 4.9 x 10(-3)), which denotes overall tooth size, and PC2 (p = 2.6 x 10(-3)), which denotes the ratio of mesiodistal diameter to buccolingual diameter.

PubMed Disclaimer

Figures

Figure 1

Figure 1

Evaluation of the Dental Morphology (A) Plaster casts of upper and lower teeth. The following abbreviations are used: U, upper; L, lower; I, incisor; C, canine; P, premolar; and M, molar. (B–D) Variation in shoveling, which refers to the development of marginal ridges on the lingual surfaces of UI1. (B) shows grade 1, (C) shows grade 3, and (D) shows grade 5. (E–G) Variation in double shoveling, which refers to the development of marginal ridges on the labial surfaces of UI1 (E) grade 1, (F) grade 3, and (G) grade 5. Arrows indicate pronounced mesial marginal ridges.

Figure 2

Figure 2

Locations and Allele Frequencies Pie charts indicate the allele frequencies for EDAR 1540T (white) and 1540C (black).

Figure 3

Figure 3

Eigenvectors in Principal Components The following abbreviations are used: U, upper; L, lower; I, incisor; C, canine; P, premolar; M, molar; BL, buccolingual diameter; and MD, mesiodistal diameter.

Figure 4

Figure 4

Distribution of Shoveling and Double-Shoveling Grades in Each Genotype The white bar indicates TT, the gray bar indicates CT, and the black bar indicates CC.

Figure 5

Figure 5

EDAR T1540C Genotypes and Principal Components The box plots depict minimum, lower quartile (Q1), median (Q2), upper quartile (Q3), maximum, and, if any, outliers for each genotype.

Similar articles

Cited by

References

    1. Hanihara T. Morphological variation of major human populations based on nonmetric dental traits. Am. J. Phys. Anthropol. 2008;136:169–182. - PubMed
    1. Hanihara K. Racial characteristics in the dentition. J. Dent. Res. 1967;46:923–926. - PubMed
    1. Turner C.G., 2nd Major features of Sundadonty and Sinodonty, including suggestions about East Asian microevolution, population history, and late Pleistocene relationships with Australian aboriginals. Am. J. Phys. Anthropol. 1990;82:295–317. - PubMed
    1. Mizoguchi Y. University of Tokyo Press; Tokyo: 1985. Shovelling: A statistical analysis of its morphology. Bulletin 26, The Univeristy Museum.
    1. Scott G.R., Turner C.G., 2nd . Cambridge University Press; Cambridge, UK: 1997. The Anthropology of Modern Human Teeth: Dental Morphology and Its Variation in Recent Human Populations.

Publication types

MeSH terms

Substances

LinkOut - more resources