Department of Psychiatry, Autism Research Centre, University of Cambridge, Cambridge, UK.
Am J Med Genet B Neuropsychiatr Genet. 2010 Jul;153B(5):994-1007. doi: 10.1002/ajmg.b.31066.
Intellectual disability is common in individuals with autism spectrum conditions. However, the strength of the association between both conditions and its relevance to finding the underlying (genetic) causes of autism is unclear. This study aimed to investigate the longitudinal association between autistic traits and intelligence in a general population twin sample and to examine the etiology of this association. Parental ratings of autistic traits and performance on intelligence tests were collected in a sample of 8,848 twin pairs when the children were 7/8, 9, and 12 years old. Phenotypic and longitudinal correlations in the sample as a whole were compared to the associations in the most extreme scoring 5% of the population. The genetic and environmental influences on the overlap between autistic traits and IQ and on the stability of this relationship over time were estimated using structural equation modeling. Autistic traits were modestly negatively correlated to intellectual ability, both in the extreme scoring groups and among the full-range scores. The correlation was stable over time and was mainly explained by autistic trait items assessing communication difficulties. Genetic model fitting showed that autistic traits and IQ were influenced by a common set of genes and a common set of environmental influences that continuously affect these traits throughout childhood. The genetic correlation between autistic traits and IQ was only modest. These findings suggest that individual differences in autistic traits are substantially genetically independent of intellectual functioning. The relevance of these findings to future studies is discussed.
智力障碍在自闭症谱系障碍患者中很常见。然而，这两种情况之间的关联强度及其与自闭症潜在（遗传）原因的相关性尚不清楚。本研究旨在调查一般人群双胞胎样本中自闭症特征与智力之间的纵向关联，并探讨这种关联的病因。在 8848 对双胞胎的样本中，当孩子 7/8、9 和 12 岁时，收集了父母对自闭症特征的评价和智力测试的表现。将整个样本中的表型和纵向相关性与人口中最极端的 5%的得分进行了比较。使用结构方程模型估计了自闭症特征与智商之间的重叠以及这种关系随时间的稳定性的遗传和环境影响。自闭症特征与智力能力呈中度负相关，无论是在极端得分组还是在全范围得分组中。这种相关性在整个儿童期都很稳定，主要是由评估沟通困难的自闭症特征项目来解释。遗传模型拟合表明，自闭症特征和智商受一组共同的基因和一组共同的环境影响的影响，这些因素在整个儿童期持续影响这些特征。自闭症特征和智商之间的遗传相关性只有中等程度。这些发现表明，自闭症特征的个体差异在很大程度上与智力功能的遗传是独立的。讨论了这些发现对未来研究的意义。
