Clinic of Orthodontics and Pediatric Dentistry, Center of Dental Medicine, University of Zurich, Zurich, Switzerland.
Department of Orthodontics and Dentofacial Orthopedics, Goldman School of Dental Medicine, Boston University, Boston, Massachusetts.
Orthod Craniofac Res. 2020 May;23(2):192-201. doi: 10.1111/ocr.12358. Epub 2019 Dec 4.
The aims of this longitudinal analysis of untreated monozygotic and dizygotic twins were to investigate vertical changes of the craniofacial structures during growth, to determine the concordance between genetically twins and to assess the genetic component for the various aspects of vertical growth.
The sample consisted of 34 pairs of untreated monozygotic twins (23 male, 11 female) and 30 untreated dizygotic siblings of multiple birth (8 male, 8 female and 14 mixed) from the Forsyth Moorrees Twin Study (1959-1975); lateral cephalograms taken from 6 to 18 years of age were analysed at 3-year intervals.
Cephalograms were traced, and longitudinal changes between twins in six angular and proportional vertical cephalometric variables (SN-NL, ML-NL, SN-ML, y-axis, PFH/AFH and LAFH/AFH) were analysed with intraclass correlation coefficients and linear regression modelling.
The concordance between monozygotic/dizygotic twins at 18 years of age was moderate to high with intraclass correlation coefficient values between 0.51 and 0.66. Additionally, sex differences in concordance at 18 years of age were found for three variables. High heritability (66%-79%) was observed for 5 of the 6 variables (LAFH/AFH, ML-NL, y-axis, SN-ML, PFH/AFH), while SN-NL showed limited heritability (34%).
Although monozygotic/dizygotic twins share at least part of their genetic material, differences in the vertical dimension were found. This supports the complex developmental mechanism of the human face and the varying influence of genetic and environmental factors.
本纵向分析未治疗的同卵和异卵双胞胎的目的是研究颅面结构在生长过程中的垂直变化，确定遗传双胞胎之间的一致性，并评估遗传因素对垂直生长各个方面的影响。
样本由来自福赛思·摩尔里斯双胞胎研究（1959-1975 年）的 34 对未经治疗的同卵双胞胎（23 名男性，11 名女性）和 30 对未经治疗的多胎异卵双胞胎（8 名男性，8 名女性和 14 名混合性别）组成；6 至 18 岁时每隔 3 年拍摄一次侧颅面片。
对颅面片进行描记，并使用组内相关系数和线性回归模型分析双胞胎之间 6 个角度和比例垂直头影测量变量（SN-NL、ML-NL、SN-ML、y 轴、PFH/AFH 和 LAFH/AFH）的纵向变化。
18 岁时同卵/异卵双胞胎的一致性为中度至高度，组内相关系数值在 0.51 至 0.66 之间。此外，在 18 岁时还发现了三个变量的性别一致性差异。6 个变量中的 5 个（LAFH/AFH、ML-NL、y 轴、SN-ML、PFH/AFH）具有较高的遗传性（66%-79%），而 SN-NL 显示出有限的遗传性（34%）。
尽管同卵/异卵双胞胎至少共享部分遗传物质，但在垂直维度上仍存在差异。这支持了人类面部复杂的发育机制以及遗传和环境因素的不同影响。
