The term "autism" has been in the news a great deal in recent years, and many parents of children with chromosome 18 conditions wonder whether, and how, this diagnosis relates to their child. The term "autism" refers to a developmental disability that is characterized by developmental delays and difficulties in social interaction and communication. There is a wide range in symptoms and severity, which is why it is often referred to as "autism spectrum disorder". People on the milder end of the spectrum may simply have some difficulties with social interactions, while those on the more severe end may be completely withdrawn from other people.

The cause of autism is not well-understood, but we know that there is a significant genetic component. The genetics of autism are quite complex. There is certainly more than one gene responsible for this condition. It is likely that many cases of autism are due to the compounded small effects of multiple genetic variants. Scientists are working hard to identify those genes and understand how they interact with each other and with the environment to cause autism. At present, there have been several dozen genes with at least a suggested link with autism. As you can see, much work remains to be done to untangle the autism puzzle.

So how does this relate to chromosome 18 conditions? When a piece of a chromosome is deleted or duplicated, that means that the genes in that region are also either deleted or duplicated. If there are some autism susceptibility genes located in that region, that person may be at an increased risk for autism. This is supported by the data collected by the Chromosome 18 Clinical Research Center. We collected surveys from parents of children enrolled in the research study. This survey asked about autistic features and behaviors noted by the parents. The results suggest that there is indeed an increased risk for autism associated with each of the conditions we study.

Condition Percent                                     A risk for autism 

                                                                      spectrum disorder

18q-                                                               62%

18p-                                                                51%

Tetrasomy 18p                                              77%

As you can see from these numbers, having a chromosome 18 condition does not mean that a person will definitely have autism. However, it does increase the likelihood of a diagnosis. It is likely that extra or missing copies of one or more genes on chromosome 18 can lead to the changes in neurologic functioning that is characteristic of autism. In other words, a chromosome 18 change can cause autism, just as it can cause visible birth defects.

If a child has autism, it is important to make the diagnosis as soon as possible. Children with autism often benefit from early intervention. In addition, a diagnosis of autism often qualifies a child for additional services. If you are concerned about the possibility of autism, speak to your child's physician. You may request a referral to a specialist who has been trained in the evaluation and diagnosis of autism. For example, a developmental pediatrician, a child psychologist, or a child psychiatrist can evaluate children for autism.