Autism is a pervasive developmental disorder which affects social and communication skills and, to a greater or lesser degree, motor and language skills. It is such a broad diagnosis that it can include people with high IQs and mental retardation -- and people with autism can be chatty or silent, affectionate or cold, methodical or disorganized. So, what exactly is an autism spectrum disorder?
Who is at Greatest Risk of Autism?
As the media pick up more and more stories about autism, parents are becoming increasingly concerned about their young children. Might their idiosyncracies be signs of autism? Autism is now diagnosed in 1 out of 150 children, and some people believe the numbers may be under-reported.
Who is at greatest risk? The bottom line is that boys are at much higher risk than girls, and that boys from families in which at least one other person is autistic are at higher risk of autism. If one identical twin is autistic, his twin is extremely likely to also be autistic (though the autism may present quite differently).
Experts estimate that three to six children out of every 1,000 will have autism (some sources cite 1 out of 166 births). Males are four times more likely to be autistic than females; the reason for this has not been determined. Autism does seem to run in families, but it is not contagious. Twins are more likely than other relatives to share autism, and identical twins are extremely likely to share autism (though it may present quite differently in different children).
Is autism really a genetic disorder created, in part, as a result of older parents? A large-scale research study conducted by a team based at Cold Spring Harbor Laboratory (CSHL) in Long Island, N.Y says, yes, perhaps.
A combination of heredity and spontaneous genetic mutation is at the root of most cases of autism. Most interestingly (and, perhaps, disturbingly), those genetic mutations may be the outcome of a societal trend toward having children later in life. In addition, some mothers, say the researchers, may carry an autism gene which does not show its effects until it is passed down -- usually to a male child.
To clarify.., experts estimate that majority of autism cases (about 2/3, or, conservatively 50%) are caused by new mutation (that is not in parents' genome but happened in sperm and eggs). There could be many risk factors for such mutation, including parental age, environmental exposure, life style etc. I do believe that the increasing parental age is behind the increase of autism.
