Down Syndrome vs Rett Syndrome in Young Children

Two very different journeys — one is present from birth and recognised early, the other usually shows itself only after a baby has been growing well for a while.

In short

Down syndrome and Rett syndrome are both genetic conditions, but they look and behave very differently in young children. Down syndrome is caused by an extra copy of chromosome 21, is usually recognised at or soon after birth, affects boys and girls equally, and brings a fairly steady, gradual developmental path. Rett syndrome is caused (in most girls) by a change in the MECP2 gene, almost always affects girls, and typically appears after a period of seemingly normal early development — with a distinctive slowing or loss of skills, especially loss of purposeful hand use, somewhere around 6–18 months.

How they differ in everyday practice

Down syndrome is often identified at birth because of recognisable physical features and is commonly confirmed soon after. Development tends to move forward steadily, just at its own pace, with strengths in social warmth and connection. Children may need support with low muscle tone, speech and learning, and many also need monitoring for heart and hearing matters — but the overall direction is one of continuous progress.

Rett syndrome follows a different shape. A baby girl usually grows and develops typically for the first several months. Then comes a plateau or regression: slowing head growth, loss of skills she once had, and most tellingly a loss of purposeful hand use replaced by repetitive hand movements such as wringing or mouthing. Communication and walking can be affected. Because it appears after an early settled period, it can feel especially confusing for families — which is exactly why prompt assessment matters.

The simplest way to hold the difference: Down syndrome is generally present and visible from birth with steady growth; Rett syndrome is generally typical at first, then a noticeable change in skills — particularly hand use — emerging in the second half of the first year onward.

When to seek a check

For any baby, see your paediatrician promptly if you notice loss of skills she once had, hand movements that replace purposeful use, slowing head growth, or a stall in development. Regression is always a reason for an early medical review — not waiting and watching. For a child already known to have Down syndrome, regular developmental follow-up keeps support timely and tailored.

The Pinnacle way

This is general information, not a diagnosis — a clinical AbilityScore® and any diagnosis are formed only at a Pinnacle Blooms Network centre, under qualified clinician care, never from an app or form. Our team looks at how your child moves, communicates and connects, then shapes the right blend of support — including occupational therapy for hand skills and daily living, and speech therapy for communication. Learn more about Down syndrome and how early support helps.

Trusted sources

The World Health Organization and the American Academy of Pediatrics on genetic conditions and developmental monitoring; HealthyChildren on recognising developmental regression and seeking timely review.

Next step — Noticed a stall or loss of skills, or want tailored support for your child? Book a developmental screening and let a Pinnacle clinician guide you with clarity and warmth.