If one child has Rett Syndrome, can my next child have it too?

When you've already walked the Rett journey with one child, it's natural to wonder what a future pregnancy might hold — here is the gentle, honest picture.

In short

In the great majority of families, Rett Syndrome arises from a brand-new (de novo) change in the MECP2 gene that was not inherited from either parent — so the chance of it happening again in a future child is usually low, around 1% or less. A smaller number of families carry a higher recurrence risk, which is exactly why genetic counselling and testing are so valuable before planning your next pregnancy. Only a clinical genetics team, looking at your child's specific gene result, can give you a figure that truly fits your family.

Understanding the genetics, gently

Rett Syndrome is most often caused by a change in a single gene called MECP2, found on the X chromosome. A few important things help make sense of recurrence:

• Most cases are de novo. The genetic change happened spontaneously, for the first time, in your child — it was not passed down. When this is confirmed, the chance of a sibling being affected is small.
• A small chance of "germline mosaicism". Occasionally a parent carries the change only in some of their egg or sperm cells without being affected themselves. This is why the recurrence risk is quoted as low rather than zero, and why testing matters.
• Rarely, a mother is a carrier. In a small number of families a mother carries an MECP2 change without symptoms (because of how the X chromosome works). Here the recurrence chance is meaningfully higher — and knowable in advance through testing.

This is why no honest answer can be a single number for everyone. The path forward is clear and reassuring: find out which situation applies to your family.

Your practical next steps

• Ask for genetic counselling — ideally before a next pregnancy. A genetic counsellor reviews your child's confirmed MECP2 result and your family history.
• Parental testing can clarify whether a parent carries the change, turning uncertainty into a clear, personal risk figure.
• Prenatal and reproductive options (such as prenatal testing) can be discussed once your family's specific risk is understood.

Knowledge here is empowering — it replaces worry with a plan.

The Pinnacle way

AbilityScore® is part of Pinnacle’s developmental assessment. Diagnosis, where needed, requires an appropriately qualified healthcare professional — never from an app or online form, and recurrence risk itself is confirmed through a clinical genetics service. While genetic questions are answered by your genetics team, Pinnacle walks beside your child's development every day — explore our therapy and developmental support for children with Rett Syndrome, understand your child's profile through the clinician-administered AbilityScore®, and see how occupational therapy supports daily skills and communication.

Trusted sources

WHO ICD-11 classifies Rett Syndrome and its genetic basis; the American Academy of Pediatrics (HealthyChildren.org) describes the typically de novo, non-inherited nature of most cases; NICE guidance supports referral to clinical genetics for counselling and recurrence-risk assessment.

Next step — For your child's day-to-day development, book a developmental assessment with a Pinnacle clinician — and ask your paediatrician for a referral to a clinical genetics service to confirm your family's specific recurrence risk.

This is general information, not a diagnosis — individual assessment and diagnosis require an appropriately qualified healthcare professional.