Tuberous Sclerosis Raises the Risk of Autism

Tuberous sclerosis (TSC) is a rare medical disorder. It's rarely mentioned relative to autism, but in fact, most people with TSC can actually be diagnosed with an autism spectrum disorder. According to the NIH:

Tuberous sclerosis (TSC) is a rare genetic disease that causes benign tumors to grow in the brain and on other vital organs such as the kidneys, heart, eyes, lungs, and skin. It commonly affects the central nervous system. In addition to the benign tumors that frequently occur in TSC, other common symptoms include seizures, mental retardation, behavior problems, and skin abnormalities. 

About 50% of all people diagnosed with TSC are also diagnosable with autism. As many as 14% of people with autism spectrum disorders AND seizure disorder may also be diagnosable with TSC. Researchers aren't completely sure why autism and TSC seem to be connected, but according to the TC Alliance, the recent finding suggests that in TC:

...there are abnormalities in the way different parts of the brain connect to each other, not only in the temporal lobes but in many other parts of the brain as well. These abnormal connections, which occur independent of tubers, are associated with ASD in children and adults with TSC. Additionally, many studies have shown that seizures and, particularly, early onset of seizures, are associated with delayed development and ASD. Therefore, it is likely a combination of factors that leads to the much higher chance of ASD.

Even with this new information, however, it is not clear whether the seizures cause autism – or whether the seizures are actually indications of abnormalities which ALSO cause autism.

It is possible to inherit TSC from a parent. Most cases, though, are due to spontaneous genetic mutations. That is, a child's genes mutate even though neither parent has either TSC or a faulty gene. When TSC is inherited, it usually comes from only one parent. If a parent has TSC, each child has a 50 percent chance of developing the disorder. Children who inherit TSC may not have the same symptoms as their parent and they may have either a milder or a more severe form of the disorder.

In most cases, the first clue to recognizing TSC is the presence of seizures or delayed development. In other cases, the first sign may be white patches on the skin. To diagnose TSC, doctors use CT or MRI scans of the brain, as well as an ultrasound of the heart, liver, and kidneys.

Once a child has been diagnosed with TSC, it is important to be aware of the strong possibility that he or she will also develop autism. While the symptoms of both disorders do overlap, they are not identical — and early treatment for autism can lead to the most positive results.