Autism spectrum disorders are associated with an elevated autoantibody response to tissue transglutaminase-2.

Rosenspire et al. (2011) compared blood samples from kids with autism and kids without it.

They looked for IgA antibodies to tissue transglutaminase-2, the same marker doctors use to screen for celiac disease.

They also checked who carried the HLA-DR3/DQ2 or DR7/DQ2 gene types, the ones linked to celiac risk.

More autistic children had high anti-TG2 antibodies than typical peers.

The rise was strongest in kids who also carried the celiac-linked HLA types.

The authors say this points to an autoimmune subtype of autism.

Bozkurt et al. (2021) extends the story. They found higher cortisol, BDNF and tPA in autistic boys, adding new blood markers that also hint at immune stress.

Ahlborn et al. (2008) seems to contradict: they saw no useful difference in GFAP autoantibodies between autism and control groups. The key difference is the antibody chosen; GFAP did not pan out, while anti-TG2 did.

Marchese et al. (2012) looked at gut bacteria instead of antibodies and found no clear pattern in autistic kids with GI problems. Pair that with Allen’s immune signal and you get a picture: the gut issue may be immune, not microbial.

If a client has autism plus GI pain, slow weight gain or mystery fatigue, ask the pediatrician about celiac labs and HLA typing. A positive anti-TG2 result could open the door to a gluten-free diet trial or GI referral. You still run your behavior program, but now you also watch for autoimmune flares that might spike problem behavior.