Early developmental regression in autism spectrum disorder: evidence from an international multiplex sample.

The team looked at the kids with autism from the families.

Parents filled out forms about when skills were lost.

They checked if regression ran in families beyond autism itself.

About 1 in the kids lost skills before age three.

Siblings did not share regression more than expected.

The loss seems tied to autism, not a separate family trait.

Warnes et al. (2005) saw the same rate of regression and also found it did not predict later IQ.

Eisenhower et al. (2006) found kids who regressed were twice as likely to have family thyroid disease.

This looks like a clash, but the 2006 paper hunted for one illness, not overall sibling patterns.

Thurm et al. (2018) later said most studies, like this one, rely on parent memory and need better methods.

When you meet a child who lost words or play skills, know that one-quarter of kids with autism do this.

Do not assume another sibling will follow the same path.

Ask about thyroid disease in the family, then focus on the child’s current needs.