Autism

Originally thought to be a result of poor parenting, autism, first diagnosed in 1943 by Dr. Leo Kanner, has now been linked to genetic influences. Autism is defined as "A psychiatric disorder of childhood characterized by marked deficits in communication and social interaction, preoccupation with fantasy, language impairment, and abnormal behavior, such as repetitive acts and excessive attachment to certain objects. It is usually associated with intellectual impairment" (American Heritage, 2000). With personality traits such as emotional disconnection, stubbornness, and inability to function in society, it is easy to see why parenting was to blame. However, further symptoms have made people realize that this syndrome must be caused by something else. People with autism generally have an error in the way they receive information in their brain. This causes them to hear colors and see sounds and other things. They also seem to have trouble expressing emotion, or expressing anything at all. Certain physical abilities may be affected as well due to errors in motor function. Autism sometimes can be mistaken for Down's syndrome and mental retardation. Yet several of those afflicted with autism have shown incredible mental ability in certain areas like mathematics. Such abilities have been portrayed in some movies. Mercury Rising, for instance, tells the story of an autistic boy who cracks an "uncrackable" code designed for top secret government files. Rain Man is another movie about an autistic man who could be considered a mathematical genius and his abilities for card counting and predicting numerical outcomes are exploited in Las Vegas. Although autism is not fully understood, we have come a long way in realizing that it is much more than just a result of poor parenting.

Autism is a term that is used interchangeably with a broader classification called pervasive developmental disorder. Other disorders related to autism include Aperger Disorder, Childhood Integrative Disorder, Autistic Disorder, and Pervasive Developmental Disorder Not Otherwise Specified. All of these disorders are generally the same with only a few subtle differences. These differences are noted by the age of onset, severity, and development of language. Diagnosis is not possible medically meaning that there is no specific tests to know if someone has a Pervasive Developmental Disorder. To identify an individual with these disorders requires observation and interview

Now that the entire human genome has been mapped it is possible to identify which and how many genes are involved in expressing autism. Several genes so far have been identified on chromosomes two, three, seven, fifteen, and X. The underlying cause of autism is not clearly known, but for certain types it has been realized that there are genetic factors. Fifteen to twenty percent of individuals with autistic disorder have an identifiable genetic condition (Exploring, 2005). There has also been strong evidence suggesting that mutations in genes can also lead to autistic disorder but these genes have not been found. There are other chromosomal regions suggesting involvement with autism but these are the five that researchers are mostly focusing on. They have narrowed down regions on chromosomes fifteen and seven to identify specific genes. Genes on Chromosome two have been associated with gastrointestinal function and these genes have been investigated and may be potential candidates for autism. "Interestingly, two different research groups have found that the chromosome 2 association is even stronger when a subset of individuals with autism and delayed speech were studied" (Buxbaum et al 2001 and Shao et al 2001).

On chromosome three, there have been two genes that are known to contribute to autism. These genes are GAT1 and OXTR gene. GAT1 is associated with a neurotransmitter that conveys messages between brain cells. A dysfunction or excessiveness of this neurotransmitter can result in the usual autistic behaviors. The OXTR gene makes a receptor protein called oxytocin. This receptor is found to help in brain development. It is also found in the uterus and mammary glands. When mice have too much of this receptor it results in repetitive and obsessive behavior.