Progress in stem cell research can help identify the underlying genetic causes of autism. So far, scientists have discovered more than 500 genetic combinations that increase the risk of autism, but it is difficult to estimate how much each of them underlies the symptoms observed in autism patients. However, using stem cells from autistic children and turning them into neurons in the lab can help find underlying causes of autism in groups of patients or even in each individual patient.
The problem with treating autism is that two people having similar symptoms can have mutations in different genes, so they will not respond to the same therapy similarly. To respond to this challenge, Alysson Muotri, a neuroscientist at the University of California, San Diego, and his team turned to study autism causes on an individual basis.
They collected cells from the skin, blood or teeth of autistic children, and turned them into neurons in the lab. This work bases on the Nobel-prize winning discovery that is possible to turn mature cells into induced pluripotent stem cells and to generate from them the cells of interest. By further examining the neurons, the researchers can understand what is wrong with them, what causes the abnormalities, and ideally how to deal with that – and all this on a patient-by-patient basis.
Earlier, this approach was used to study autism caused by known genetic mutation, namely, Rett syndrome and Timothy syndrome. However, in a recent study, Muotri and colleagues used the approach to study autism without know genetic case. They took cells from baby teeth of 8-year old boy, turned them into induced pluripotent stem cells, and turned the latter into neurons. The neurons did not look normal under the microscope, and did not function properly. They also found an underlying gene mutation that disrupted functioning of a TRPC6 gene, responsible for regulation of the influx of calcium ions into cells.
Then, the researchers treated the neurons with hyperforin, a drug boosting TRPC6 activity. The neurons became more normal in appearance and their functioning became more proper.
To continue the study, the parents of the boy tried giving him hyperforin. The boy took St. John’s wort - the herb containing hyperforin - for about a month. His father, therapists, and school teachers reported an improvement in the boy’s focus and social behavior, but the mother did not see any changes in the boy.
Although TRPC6 gene mutation may not be the sole genetic cause of autism in this patient, the approach demonstrates how the technique can be applied to discover autism causes on individual level. However, this is not going to be cheap - Muotri estimates that creating and characterizing neurons from a single patient would cost about $100,000. Because of the high costs for individual patients, researchers will focus on identifying different categories of autism with different underlying causes to develop treatments for groups of patients with the same disease causes.