Researchers have discovered that siblings of people with autism show a similar pattern of brain activity to that seen in people with autism when looking at emotional facial expressions.

The research, led by Dr MD Spencer and published in the journal Translational Psychiatry, showed that the neural response to facial expression of emotion differs between unaffected siblings of people with autism and healthy controls with no family history of autism.

Richard Mills, director of research at The National Autistic Society, said: "Autism is highly heterogenous. This study does not answer all the questions on its causes; but it does give the scientific community the opportunity to further investigate what genes the 'biomarker' (in this case, reduced brain activity) affects, and possibly expand on our theories on the causes of autism. As such, we welcome its findings. "Dr Spencer's study confirms the importance of genetic factors in some forms of autism. The findings appear to be consistent with other MRI and genetic studies in identifying brain regions and structures implicated in autism. "Importantly, this study finds a biomarker only in the response to emotions of one part of the brain - related to empathy. It does not suggest that siblings of people with autism will develop the condition or are at increased risk, though we already know there is a higher incidence of some forms of autism in subsequent children if one child in the family has autism. "The causes of autism are not yet understood but a combination of genetic and environmental factors are known to be very important."

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