Chromosomes Associated With Autism Spectrum Disorders

One point on which genetic researchers studying autism will agree is the multigenetic requirement for this disorder, also known as polygenic inheritance.  This means that more than one gene is attributed to autism.  Since it is a spectrum disorder with a wide range of symptoms and varying degrees of severity, this theory is not unfounded.  Numerous genes on several different chromosomes are being investigated.  Much of the research so far examines five different chromosomes thought to have a direct link to autism--chromosomes 2, 3, 7, and 15 as well as the X chromosome.  Here is a brief update of some of the results:

• Chromosome 2 is the second largest chromosome in the human genome and is associated with language development. The gene SLC25A12 located on this chromosome has an increased presence in individuals with autism and their family members compared to families without autism. 
• Chromosome 3 contains genes linked with early brain development. Dysfunction in these genes may cause mixed messages in the brain cells and improper early brain development.
• Chromosome 7 is associated with language development and recent studies have found disruption of the MET gene on this chromosome is linked to autism and a gastrointestinal disorder with which it is commonly associated.
• Duplications of certain regions on chromosome 15 are associated with a lack of language skills, seizures, and anxiety and are seen more frequently in individuals with autism.
• The X chromosome is directly linked to Rett's disorder, another developmental disorder fwhich alls within the autism spectrum. Rett's syndrome is more common in females; The condition is fatal in males. Chromosome X is also linked to the chemical messages passed through the central nervous system. Genes located on this chromosome make proteins called neuroligins. These proteins work with the central nervous system to help cells chemically communicate with each other.