哈佛研究員發現了6個新的基因涉及自閉症, 這些基因在腦子裡造成混亂停滯, 以至於不可能適當地形成新的連合.

這個研究發現也幫助解釋, 為什麼積極強烈的教育規劃 (intense education programs) 可以幫助一些自閉症的孩子, 因為某些基因對不消失的經驗是有反應, 而這些基因只是被困住而無法發揮功能.

以行為治療法知名的蓋瑞.固斯坦博士( Dr. Gary Goldstein of the Kennedy Krieger Institute in Baltimore, http://www.kennedykrieger.org/kki_staff.jsp?pid=1901)說, “所以你必須在電路那裡使勁推動”， 他說, “遺傳學建議我們的作法是合理的, 當我們不停地用積極強烈的教育規劃去推動幼小的自閉兒學習,他們會突然通過學習瓶頸;但是這個研究下的更大訊息是,每個自閉症的現象太不同,以至於不能想像能以一個簡單的基因來測試它,反而將自閉症者規化成有廣大多樣的基因缺陷;波士頓兒童醫院的遺傳學院長(chief of genetics at Children’s Hospital Boston )克里斯托弗.華席醫學博士(Dr. Christopher Walsh)說 “幾乎每個自閉症的孩子都有他們自己的特殊起因” , 克里斯托弗.華席醫學博士專門研究自閉症的源由,並出版在星期五科學學報(Friday’s edition of the journal Science ), 自閉症的現象從腦部的範圍下研究很難明白,這個範圍包括從溫和的Asperger的綜合症狀,到嚴重的社交孤立,語言溝通的障礙和重複性的失常行為.

從孿生的家庭到有重覆自閉症者的家庭史的廣泛研究,基因的確在自閉症中扮演一個大角色.克里斯托弗.華席醫學博士說, “但到目前為止，確認是基因起因而有的自閉症案例只有15%(在美國)”, 所以克里斯托弗.華席醫學博士的研究團隊採取了一項新的策略, 他們轉向了中東,一個傾向只有表兄弟/姊妹能結婚的的大家庭世界，以能增加可能性,來發現罕見基因的特徵。  他們從喬丹、沙特阿拉伯、科威特、阿曼、巴基斯坦、卡塔爾、土耳其和阿拉伯聯合酋長國(Jordan, Saudi Arabia, Kuwait, Oman, Pakistan, Qatar, Turkey and the United Arab Emirates),吸收了88個以表兄弟婚姻且有高機率的自閉症家庭，華席醫學博士的研究團隊比較了家庭成員中的DNA, 查尋什麼是隱性變化(recessive mutations),例如健康正常的父母體內會有繼承的缺陷基因，而孩子的自閉症是因繼承來自雙方父母的缺陷基因.在某些案例中,研究團隊發現追蹤隱性規則(recessive rule ),他們發現了一大區域的DNA不見了!這個DNA不見的地區在每個家庭中有不同的變化,但至少有六個基因在自閉症中扮演一個角色.

這個發現為什麼重要:所有的基因似乎都是一個學習基礎網絡中的一部分,也就是腦細胞中的神經元藉著彼此之間的連接, 稱為突觸(synapses ),來反應新的經驗.在自閉症現象發生的頭兩年, 突觸會迅速地形成並且成熟,而且有多餘的部分在後面 “被修剪”( pruned ); 換句話說，嬰孩的腦子是由他的第一經驗被逐漸地塑造，以便使腦能有結構地進行學習和其他最新生活的功能.

By Associated Press – Texarkana Gazette        7/12/2008

Harvard researchers have discovered half a dozen new genes involved in autism that suggest the disorder strikes in a brain that can’t properly form new connections.

The findings also may help explain why intense education programs do help some autistic children—because certain genes that respond to experience weren’t missing, they were just stuck in the “off” position.

“The circuits are there but you have to give it an extra push,” said Dr. Gary Goldstein of the Kennedy Krieger Institute in Baltimore, which wasn’t involved in the gene hunt but is well-known for its autism behavioral therapy. The genetics suggest that “what we’re doing makes sense when we work with these little kids—and work and work and work—and suddenly get through,” he said. But the study’s bigger message is that autism is too strikingly individual to envision an easy gene test for it. Instead, patients are turning out to have a wide variety, almost a custom set, of gene defects. “Almost every kid with autism has their own particular cause of it,” said Dr. Christopher Walsh, chief of genetics at Children’s Hospital Boston, who led the research published in Friday’s edition of the journal Science. Autism spectrum disorders include a range of poorly understood brain conditions, from the mild Asperger’s syndrome to more severe autism characterized by poor social interaction, impaired communication and repetitious behaviors.

It’s clear that genes play a big role in autism, from studies of twins and families with multiple affected children. But so far, the genetic cause is known for only about 15 percent of autism cases, Walsh said. So Walsh’s team took a new tack. They turned to the Middle East, a part of the world with large families and a tendency for cousins to marry, characteristics that increase the odds of finding rare genes. They recruited 88 families with cousin marriages and a high incidence of autism, from Jordan, Saudi Arabia, Kuwait, Oman, Pakistan, Qatar, Turkey and the United Arab Emirates. They compared the DNA of family members to search for what are called recessive mutations — where mom and dad can be healthy carriers of a gene defect but a child who inherits that defect from both parents gets sick. In some of the families, they found large chunks of missing DNA regions that followed that recessive rule. The missing regions varied among families, but they affected at least six genes that play a role in autism. Here’s why this matters: All the genes seem to be part of a network involved in a basic foundation of learning—how neurons respond to new experiences by forming connections between each other, called synapses. In the first year or two of life—when autism symptoms appear—synapses rapidly form and mature, and unnecessary ones are “pruned” back. In other words, a baby’s brain is literally being shaped by its first experiences so that it is structurally able to perform learning and other functions of later life.