Changing the perspective on early development of Rett syndrome.

The team looked at home videos of babies who were later diagnosed with Rett syndrome. They watched how each baby used sounds and gestures before age two.

They compared what they saw to the old belief that these babies develop normally until regression hits.

Every baby already showed clear speech-language delays in the first two years. Babble was late, eye contact was brief, and shared sounds were rare.

The data say the 'normal pre-regression' story is wrong. Delays are present long before the obvious loss of skills.

Leaf et al. (2012) found the same thing in toddlers with the 'preserved speech' variant. Those girls also had big socio-communicative gaps before regression. Together, the two papers form a direct replication: early delay is the rule, not the exception.

Ortiz et al. (2014) showed that preschoolers at risk for dyslexia already struggle with rapid sound patterns. Like the Rett babies, the warning signs show up before the main problem is visible.

Takahashi et al. (2023) looked at people labeled 'pre-linguistic' due to profound disabilities and discovered quiet but real subvocal words. The Rett study and the PMLD study both tell us to doubt claims of 'no language.' If you look deeper, you often find capacity that was missed.

Stop waiting for regression. Start measuring babble, eye contact, and turn-taking as soon as a girl is flagged for possible Rett. Early data give you a baseline for intervention and help families understand that delays are part of the syndrome from the start.