This week's edition of Nature has 3 back-to-back articles from 3 different groups who have sequenced the "exomes" (the part of the genome that codes for proteins) of a huge number (almost 600) of autism trios (in genetics, a trio is parents and affected child), as well as almost 1,000 additional autistic people. This massive effort yielded 3 new genes related to autism, CHD8, KATNAL2 and SCN2AThe other interesting bit of information is that fathers older than 35 years old are much more likely to pass on these mutations. . But the most important result is that these studies conform that autism is an extremely heterogeneous group of disorders, with >1,000 genes contributing to the risk of developing the condition. Although it is not clear how mutations or variants of these genes contribute to the disease, CHD8 is very intriguing because it is a chromatin remodeling factor. Chromatin refers to the packaging and "wrapping" of genes, it has to do with gene expression, it is part of epigenetics, a very hot new field. Recent papers have identified germline mutations in chromatin remodeling factors in syndromes that include intellectual disability and epilepsy, pointing to a role of chromatin remodelling in disorders of the central nervous system. For a very detailed blog describing these 3 articles (very technical), go here: Autism exomes arrive. This NYT article is more readable although less detailed: Scientists Link Gene Mutation to Autism Risk.
From the HuffPo:
* Teams identify four new autism risk genes
* Older fathers more likely to pass autism to offspring
By Julie Steenhuysen
CHICAGO, April 4 (Reuters) - A sweeping study of hundreds of families with autism has found that spontaneous mutations can occur in a parent's sperm or egg cells that increase a child's risk for autism, and fathers are four times more likely than mothers to pass these mutations on to their children, researchers said on Wednesday.
The results of three new studies, published in the journal Nature, suggest mutations in parts of genes that code for proteins - called the exome - play a significant role in autism.
And while these genetic mistakes can occur across the genetic code, and many are harmless, they can cause big problems when they occur in parts of the genome needed for brain development. One of the three teams found these glitches may result in a five to 20 times higher risk of developing autism.
Read the rest here.
From the NYT article (I try not to chew on what I can't swallow =):
The emerging picture suggests that the search for therapies will probably be a very long one, and that what is known generally as autism may represent a broad category of related but biologically distinct conditions. But both Dr. Eichler’s and Dr. Daly’s groups found some evidence that high-risk genes interact in shared biological processes.
There are so many different types of manifestations and degrees of manifestations labeled autism that it can't not be the case. You are dealing with two incredibly complex fields of research that are both in their pre-infancy: how a brain grows and how a brain works, genetics and cognition.
I wonder wht's the percentage of the population affected by, subjected to, autism. Also, when we see examples, it always seems to be autistic children not adults. Do autistic adults have a less life expectancy ?
Well, those are many questions that I will have to research and let you know my findings...
No, the life expectancy of autistic adults is normal. Children are always a more poignant example for any disease, I think. Many parents participate in forums about the difficulties of raising an autistic child. Also, interventions are more likely to succeed on young people than on adults.