台灣青少年青春期發展之雙胞胎研究

Abstract

目的：青春期是一個重要的發展時期，而且在許多精神疾患扮演重要的角色。在過去研究中，針對單一的測量指標，發現有遺傳的貢獻。然而，青春期發展有越來越早啟動的現象，而且不同的國家之間的差異。本研究目的主要針對台灣青少年雙胞胎，探討遺傳因子與環境因子對青春期各項指標的相對貢獻。 方法：研究個案來自於兩個不同的研究計畫，分別進行於1996-1998年以及2001-2004年，共有160對男性雙胞胎、254女性雙胞胎以及54對異性的配對納入本研究的分析。使用中文版的青春期發展量表測量青春期的各項指標，雙胞胎的胎性判定結合身體相似性問卷以及基因定型檢驗兩種方法。利用結構方程式模型建構來估計線性遺傳、非線性遺傳、共享環境與非共享環境因子佔所有變異的百分比。 結果：女性每項青春期指標的線性遺傳佔40%到67%，而男性佔38%到75%。在一些項目有些微的共享環境因子的影響，女性約佔11%到36%，男性約佔12%到21%。女性初經有88%可被共享環境因子所解釋，而女性初經年齡則有73%的變異受到線性遺傳因子的影響。就女生而言，若將青春期分期當做連續變項進行分析，發現沒有線性遺傳因子的效應，若當做類別變項則有63%的變異是來自於現性遺傳因子；就男生而言，利用連續型方法估計到的線性遺傳百分比為49%，利用類別型方法則為75%。 結論：由於青春期發展有趨早啟動的現象，因此環境影響因素不能被忽視，但是本研究發現在台灣青少年中，一些青春期發展主要的特徵，其遺傳的因子都有相當的貢獻。

Objective: Puberty is a critical developmental period and may play an important role on several psychiatric disorders. Despite that contribution from genes to single measures of puberty was indicated in previous twin studies, prominent differential secular trends in pubertal timing were also noted in different countries. The purpose of this study is to examine the relative contributions of genetic and environmental factors to pubertal development assessed comprehensively among adolescent twins in Taiwan, where a steady decline in pubertal timing has been noted in the past decades. Methods: Participants were adolescent twins recruited from two sources. One was recruited in Taipei City during 1996-1998, and the other was in Taipei City or Taipei County during 2001-2004. A total of 160 pairs of male twins, 254 pairs of female twins, and 54 opposite-sex pairs were included. A Chinese-version of Puberty Developmental Scale was used to measure various aspects of pubertal development. Zygosity was determined using a combination of physical similarity questionnaire and DNA typing. We used structural equation modeling to estimate parameters of additive genetic (A), shared environmental (C), dominant genetic (D), and non-shared environmental (E) factors in accounting for the variation of both individual pubertal development items and composite pubertal scores in either dichotomized or continuous form of variable. Results: For each pubertal development item common to both genders, including height growth spurt, body hair, and skin change, the proportion of the variance attributed to additive genetic factors ranged from 0.40 to 0.67 for girls and from 0.39 to 0.58 for boys. Moderate contributions from shared environmental factors were also found to breast development (29%), height growth (11%), body hair (36%), and pubertal stage (28%) in girls and skin change (19%), body hair (21%), and facial hair (12%) in boys. For girls, the majority of the variance for the presence of menarche (88%) was explained by shared environmental factors, while that for age of menarche (73%) was by genetic factors. In terms of pubertal stage, the contribution from genes was estimated to be zero using continuous approach and 63% of the variance using categorical approach for girls; meanwhile, for boys, the corresponding figures were 49% and 75%, respectively. Conclusions: There is substantial genetic contribution to pubertal development for adolescents in Taiwan despite non-negligible influences from shared environmental factors that might have resulted in a prominent secular decline in pubertal timing.