If you’re a mom of an autistic child, you may have wondered at some point, ” Was there something going on in my body before my child was born?”

For a long time, we didn’t have a scientific way even to explore that question. That is starting to change. Today, I want to talk about a new blood test for moms that looks at a specific biological subtype of autism. 

Not autism as a whole. One clearly defined subtype. And I want to explain what it actually means in a calm, grounded, and science-based way.

Understanding the MAR Autism Test

MAR Autism Test, developed by Mara Biosystems. It identifies a subtype of autism called Maternal Autoantibody-Related Autism, MARA. 

Here’s the most important thing to understand. This is a blood test for the mother, not the child. 

The Science Behind It

Your immune system makes antibodies to protect you from infections. Sometimes, the immune system makes autoantibodies. And these are antibodies that accidentally react to the body’s own proteins. In some women, certain autoantibodies can cross the placenta during pregnancy.

When this happens, they can interact with proteins that are important for early brain development. The MAR autism test looks for a specific pattern of these autoantibodies in a mother’s blood. One of the key proteins researchers study is called CRMP1.

CRMP1 plays a role in how brain cells grow and connect. When these autoantibodies are present, studies show a much higher likelihood that a child’s autism fits this immune-related subtype. This subtype is not rare.

Research suggests maternal autoantibody-related autism may account for about 18 to 26 percent of autism diagnoses. That’s roughly 20 percent, one in five. Children with this subtype often show more repetitive behaviors, higher scores on autism assessments, and sometimes greater overall support needs. 

That doesn’t define who they are; we know that, but it does help explain why symptoms may look more intense.

How the Test Is Used

How is this test actually used? It’s a simple blood draw from the mother. It can be used when a child is already diagnosed with autism, when a younger sibling is showing early signs, or before getting pregnant.

Two important clarifications. One, this test is not used during pregnancy, and it is not a general autism screening test. It targets one specific immune-related mechanism.

Accuracy and What It Means

In clinical studies, this test shows very high specificity. That means very few false positives. That’s good. Animal studies help explain why this matters. 

Exposure to these autoantibodies during pregnancy changes early brain signaling and immune pathways. That gives us a biological explanation, not just behavioral observations, which has been a problem with autism in the past. It’s all based on observation. There’s very little biological.

What If the Test Is Positive?

Now the question parents always ask is, what happens if the test is positive?

A positive result does not change your child’s diagnosis, but it gives clarity. Doctors can explain that this is a non-genetic immune-mediated subtype of autism. It supports that. 

Then therapies and supports are often prioritized earlier, especially if families are on wait lists. Planning for siblings or future pregnancies may also be discussed. Right now, there’s no medication that removes these autoantibodies.

Research is ongoing, but early targeted support still makes a meaningful difference in the life of someone with autism. This is about precision and not blaming the mom.

Why This Shift Matters

For decades, autism has been diagnosed based only on behavior. This test represents a shift towards understanding biology, towards identifying meaningful subtypes, towards precision medicine in autism care. The research behind MAR comes from institutions like UC Davis, with work going back many years. This test became commercially available in late 2025, so it’s pretty recent.

It’s the first blood test for this specific autism subtype.

Final Thoughts

In closing, this test does not explain all of autism. It does not predict outcomes, and it does not replace clinical care, but it does give families something we’ve needed for a long time. Real biological information. Earlier and with clarity, if you’re considering taking this test, talk with a qualified health care provider about whether it makes sense for your situation.

Confused by all the information about autism? I’ve got you.Click the link to see how we can work together. Let me break down the science and provide you with clear, actionable steps to make your path forward easier