WHILE the causes of autism are still unclear, we are closer than ever to a blood test that could detect the disease very early on 鈥� perhaps even at birth.
鈥淗aving a blood test for autism would be a dream,鈥� says Daniel Geschwind of the University of California, Los Angeles. 鈥淚t would revolutionise the field.鈥�
Two teams say they have found measurable differences in blood of children with autism. David Amaral鈥檚 group at the University of California, Davis, has used a high-speed blood analysis method provided by the company SurroMed of Menlo Park, California. The researchers compared blood from 70 children with autism with that of 35 children without the disorder, all between 4 and 6 years old. They found differences in the levels of more than 100 proteins and several small molecules, and higher levels of two types of immune cells in the autistic children.
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And Paul Ashwood鈥檚 team, at the same university, has found different levels of immune-signalling proteins called cytokines in autistic children.
Other experts, however, point out that it is not yet clear if these differences are specific to autism. Researchers have reported finding markers for autism in blood before, but they have turned out not to be specific to the disorder. But Amaral is confident that even if this is the case, it will be easy to make screening more sensitive, to reveal differences distinctive to autism.
Next, he plans to study blood from a large group of children at regular intervals from birth, in the hope of identifying signs present at a very young age. 鈥淭he logic is inescapable,鈥� he says. 鈥淎utism is a genetic disorder. Genes are expressed in the blood so if you search hard enough, you will find some kind of marker in the blood.鈥�
Autism is not usually diagnosed until a child is 3 or 4, when abnormal behaviour becomes more apparent. Identifying it earlier on would not only help us understand the disorder better, but would also allow doctors to try treatments that might reduce the severity of symptoms or perhaps prevent it altogether. Some researchers are even hunting for biomarkers in the blood of pregnant women, although they have no results to report as yet.
Both Amaral鈥檚 and Ashwood鈥檚 findings also add to the evidence that disruption of the immune system is linked to autism. In November, for instance, autism was linked to inflammation of the brain. 鈥淭he interesting thing is that the immune system and neurological system are intimately related. There is a lot of crosstalk,鈥� says Judy Van De Water, a member of Ashwood鈥檚 team. She also points out that cytokines 鈥� the markers identified in Ashwood鈥檚 study 鈥� are known to affect sleep, and that many people with autism also have sleep disorders.
