 |
|||||||||||||
 |
|
 |
|||||||||||
 |
 |
||||||||||||
Go read for yourself. Here's part of it: In the case of autism, the likelihood that the sibling of an affected child also would be affected is between three and six percent. This number is small enough that family doctors probably would never see enough cases of two affected siblings in the same family to suspect a genetic influence. Nonetheless, this incidence is about 100 times greater than the rate at which autism affects unrelated people in the population. Compounding the problems of rarity, another difficulty in detecting the genetic origins of autism is the lack of family pedigrees. Unlike people who inherit Huntington disease, a genetic disease that does not strike until after the affected person has reached reproductive age, persons affected with autism are so socially disabled that they never marry and have children. Thus, researchers do not have the extended family histories that have played such a critical role in the identification of genes implicated in cystic fibrosis, breast cancer, and other diseases. Such a high genetic contribution appears to be the exception rather than the rule when considering complex behaviors. This is probably because a relatively small number of genes may be involved in autism (but certainly more than one), whereas other behaviors may be influenced by many genes. To identify the specific genes influencing autism, scientists initiated an international collaboration in 1996. As a result of this work and further studies, we someday may have a better understanding of the brain differences that lead to the bizarre and conflicting behaviors of persons who are autistic. Post a comment in response: |
| © 2002-2008. Blurty Journal. All rights reserved. |