How relevant are GFAP autoantibodies in autism and Tourette Syndrome?

Doctors drew blood from people with autism, Tourette syndrome, and typical controls. They measured antibodies that attack GFAP, a brain-support protein.

The team wanted to know if these antibodies cause autism or tics. They compared levels across the three groups.

Antibody levels were the same in every group. High or low titers did not track with diagnosis.

The authors say GFAP antibodies are innocent bystanders, not disease drivers.

Song et al. (2024) and Nijs et al. (2016) also found no autism signal in two other brain chemicals, GABA and glutathione. Together the papers shrink the list of single-molecule blood tests that will ever help you screen for ASD.

Rosenspire et al. (2011) looks like a contradiction. They did find higher anti-TG2 antibodies in some autistic kids. The difference is target: TG2 antibodies link to gut autoimmunity and certain HLA genes, while GFAP antibodies do not. Same blood, different story.

Root et al. (2017) and Marchese et al. (2012) add more nulls. Urine IAG and gut microbiota also fail to split autism from typical. The pattern is clear: easy single biomarkers keep coming up empty.

You can skip GFAP antibody tests when families ask about “biomedical” workups. Save money and time. Focus your assessments on skill-based data—language samples, VB-MAPP, functional analyses—instead of hunting blood markers that science keeps ruling out.