Are Autism and Down Syndrome Related?

Autism Spectrum Disorder (ASD) and Down syndrome are two different developmental conditions that can affect how a person communicates, learns, and interacts with others. But are autism and Down syndrome related? While they are separate diagnoses, it is possible for a person to have both conditions—a situation known as co-occurring diagnoses.

1. What Is Down Syndrome?

Down syndrome is a genetic condition caused by the presence of an extra copy of chromosome 21 (trisomy 21). It leads to physical characteristics, developmental delays, and varying levels of intellectual disability. It can be identified at birth or during pregnancy through genetic testing.

2. What Is Autism?

Autism Spectrum Disorder is a neurodevelopmental disorder that affects communication, social interaction, and behavior. It is not caused by a single gene, and its exact causes involve a combination of genetic and environmental factors.

3. Can a Person Have Both Autism and Down Syndrome?

Yes, a person can have both autism and Down syndrome. Studies estimate that 5% to 15% of individuals with Down syndrome may also meet the criteria for autism. However, autism is often underdiagnosed in people with Down syndrome because some overlapping behaviors—like delayed speech or social difficulties—may be attributed solely to Down syndrome.

4. How Are They Different?

While both conditions affect development, they have distinct causes and features:

Down syndrome is caused by a known genetic change (an extra chromosome).

Autism is a spectrum condition with a wide range of symptoms and no single known cause.

People with Down syndrome typically show more social interest than those with autism, although both may experience communication challenges.

5. Why Early Diagnosis Matters

When autism co-occurs with Down syndrome, early and ACC

urate diagnosis is crucial. It ensures:

Access to specialized therapies like speech, occupational, and behavioral therapy

More tailored educational plans

Better long-term support for both the child and their family

Find out more in The Autism Relationship Guide available on AutismVictory.com.