Many of the seemingly disparate genetic mutations recently discovered in autism share common underlying mechanisms, according to the results of a large international study published on the 11 July. The mutations seem to disrupt genes that are active in the developing brain and which are turned on and off in response to experience.

    The researchers, who are based at Harvard University, took advantage of a short cut to genetic discovery by sampling families in which parents are cousins. This increases the likelihood that offspring will inherit rare mutations.

    They found genes and mutations associated with autism in 88 large families from the Arab Middle East, Turkey and Pakistan, in which cousins married and had children with the disorder. The results appear in the journal Science.

    Christopher Walsh, lead author, said: “To map a gene for autism in American families, averaging two to three kids per family, you would need to pool many families. In [the Middle East] one family alone may be enough to definitively localise a gene.”

    “There appear to be many separate mutations involved, with each family having a different genetic cause,” added Thomas Insel, director of the US National Institute of Mental Health. “The one unifying observation is that all the relevant mutations could disrupt the formation of vital neural connections during a critical period when experience is shaping the [young child's] developing brain.”

    7月11日發表的一項大型國際研究結果顯示，最近在自閉癥患者中發現的很多基因突變雖然看似彼此不同，實際上卻有共同的內在機制。這些突變可能會破壞在大腦發育中表現活躍的基因，面對不同的外部體驗，人體會選擇是否讓這些基因發揮作用。

    來自美國哈佛大學(Harvard University)的研究人員在基因發現中走了一條捷徑：只對父母是表親或堂親的家庭進行采樣，從而增加了子女遺傳罕見突變的可能性。

    在88個父母為表親或堂親、子女患有自閉癥的中東阿拉伯、土耳其和巴基斯坦的大家庭中，研究人員發現了與自閉癥有關的基因及基因突變。他們的研究結果發表在《科學》(Science) 雜志上。

    該論文的第一作者克里斯托弗•沃爾什(Christopher Walsh)說：“美國家庭一般有兩三個子女，要繪制這些美國家庭的自閉癥基因圖，你需要匯集很多家庭樣本。而（在中東）只對一個家庭進行研究，可能就足以確定基因所在位置。”

    “由于每個家庭的遺傳因素各不相同，似乎會涉及許多不同的基因突變，”美國國家心理健康研究所(National Institute of Mental Health)所長托馬斯•因澤爾(Thomas Insel)補充道。“一項相同的觀察結果是，在外部體驗令幼兒大腦發育定型的關鍵時期，所有相關基因突變都可能破壞至關重要的神經連接的形成。”