Researchers at Kings College London and Karolinska Institute in Stockholm found that the risk triples if there is a half-brother or sister or a cousin with a diagnosis.
Author Dr Sven Sandin told The Telegraph:
“Our study was prompted by a very basic question which parents often ask: ‘if I have a child with autism, what is the risk my next child will too?’. The risk of autism increases according to how close you are genetically to other relatives with autism. We can now provide accurate information about autism risk which can comfort and guide parents and clinicians in their decisions. Some will want to avoid having another autistic child, but for others it won’t be a problem. “
Research combed through medical records of children born in Sweden between 1982 and 2006, to explore if there was a strong hereditary link for autism diagnosis. Of the two million medical records read – 14,516 children were diagnosed as being on the spectrum somewhere.
The study published in JAMA was led by Professor Avi Reichenberg, of Mount Sinai Seaver Center for Autism Research. He said:
“Recent research efforts have tended to focus on genes, but it’s now clear that we need much more research to focus on identifying what these environmental factors are.
“In the same way that there are multiple genetic factors to consider, there will likely be many different environmental factors contributing to the development of autism.”