Kimura Ryosuke, Yamaguchi Tetsutaro, Takeda Mayako, Kondo Osamu, Toma Takashi, Haneji Kuniaki, Hanihara Tsunehiko, Matsukusa Hirotaka, Kawamura Shoji, Maki Koutaro, Osawa Motoki, Ishida Hajime, Oota Hiroki
Transdisciplinary Research Organization for Subtropics and Island Studies, University of the Ryukyus, Okinawa, 903-0215, Japan.
Am J Hum Genet. 2009 Oct;85(4):528-35. doi: 10.1016/j.ajhg.2009.09.006.
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.
上门牙的铲形是亚洲和美洲原住民人群的常见特征，但在非洲和欧洲人群中很少见或不存在。与其他常见的牙齿特征一样，涉及牙齿铲形的基因多态性尚未明确。在外胚层发育不良A受体（EDAR）中，功能失调的突变会导致少汗性外胚层发育不良，存在一个非同义衍生变体1540C（rs3827760），其地理分布与牙齿铲形相似。最近有报道称该等位基因与亚洲人特有的头发厚度有关。我们旨在阐明EDAR 1540C是否也与牙齿形态有关。为此，我们测量了牙冠直径和牙齿铲形等级，并分析了东京周边居民和冲绳县石垣岛两个日本人群中牙齿特征与EDAR基因型之间的相关性。个体中EDAR 1540C等位基因的数量与牙齿铲形等级密切相关（p = 7.7 x 10(-10)）。该等位基因的作用是累加性的，解释了铲形等级总方差的18.9%，这大约相当于先前报道的该性状遗传力的四分之一。为了对个体水平的计量数据进行降维，我们进行了主成分分析，得到了PC1 - 4，对应四种牙齿大小模式；这一结果意味着牙齿形态涉及多个因素。1540C等位基因也显著影响表示整体牙齿大小的PC1（p = 4.9 x 10(-3)）和表示近远中径与颊舌径比值的PC2（p = 2.6 x 10(-3)）。
