Handedness and language lateralization are the most investigated phenotypes among functional hemispheric asymmetries, i.e. differences in function between the left and the right half of the human brain. Both phenotypes are left hemisphere-dominant, while investigations of the molecular factors underlying right hemisphere-dominant phenotypes are less prominent. In the classical line bisection task, healthy subjects typically show a leftward attentional bias due to a relative dominance of the right hemisphere for visuospatial attention. Based on findings of variations in dopamine-related genes affecting performance in the line bisection task, we first tested whether DNA methylation in non-neuronal tissue in the promoter regions of DBH, SLC6A3, and DRD2 are associated with line bisection deviation. We replicated the typical behavioral pattern and found an effect of DNA methylation in the DBH promoter region on line bisection deviation in right-aligned trials. A second exploratory analysis indicated that an overall DNA methylation profile of genes involved in dopamine function predicts line bisection performance in right-aligned trials. Genetic variation in dopamine-related genes has been linked to attention deficit hyperactivity disorder (ADHD), a neurodevelopmental trait associated with rightward attentional bias. Overall, our findings point towards epigenetic markers for functional hemispheric asymmetries in non-neuronal tissue not only for left hemisphere-dominant, but also for right hemisphere-dominant phenotypes.

惯用手和语言偏侧化是功能性半球不对称（即人脑左半球和右半球之间的功能差异）中研究最多的表型。两种表型均以左半球为主，而对右半球主导表型背后的分子因素的研究则不太突出。在经典的线平分任务中，由于右半球在视觉空间注意力方面相对占主导地位，健康受试者通常表现出向左的注意力偏差。基于影响线平分任务表现的多巴胺相关基因变异的发现，我们首先测试了DBH 、 SLC6A3和DRD2启动子区域的非神经元组织中的 DNA 甲基化是否与线平分偏差相关。我们复制了典型的行为模式，并在右对齐试验中发现了DBH启动子区域 DNA 甲基化对线平分偏差的影响。第二项探索性分析表明，参与多巴胺功能的基因的整体 DNA 甲基化谱可以预测右对齐试验中的线平分性能。多巴胺相关基因的遗传变异与注意力缺陷多动障碍（ADHD）有关，这是一种与右向注意力偏差相关的神经发育特征。总体而言，我们的研究结果指出，非神经元组织中功能性半球不对称的表观遗传标记不仅适用于左半球主导的表型，而且还适用于右半球主导的表型。