Rett Syndrome
Are boys more likely to have Rett Syndrome?
Rett Syndrome is far more likely in girls than boys. It is caused by a change in the MECP2 gene on the X chromosome; girls have a second X that allows the classic pattern, while boys with the same change are usually affected far more severely and differently. A clinical AbilityScore and any diagnosis are formed only at a Pinnacle Blooms Network centre.
One of the most common questions parents ask about Rett Syndrome is whether it affects boys and girls differently — and the answer is unusual.
In short
No — Rett Syndrome is overwhelmingly seen in girls, not boys. It is caused by a change in the MECP2 gene on the X chromosome, and because of how that gene works, the classic picture of Rett Syndrome almost always occurs in girls. Boys can carry a change in the same gene, but the effect on them is usually very different and often far more severe. So the simple answer is: Rett Syndrome is far more likely in girls.Why girls, not boys
Girls have two X chromosomes, so a girl with a MECP2 change still has a second, working copy of the gene in many of her cells. This is what allows the characteristic Rett pattern — a period of typical early development, then a slowing or loss of acquired hand skills and communication, and distinctive repetitive hand movements — to emerge in classic form.Boys have only one X chromosome and no second copy to balance it. A typical Rett-causing MECP2 change in a boy usually leads to a much more serious condition, often recognised in early infancy, rather than the classic Rett presentation seen in girls. This is why, when clinicians describe the typical course of Rett Syndrome, they describe it in girls.
If your daughter showed steady early progress and then began to lose hand use or babble, or developed unusual hand-wringing or hand-to-mouth movements, that is a reason for a prompt developmental review — not a reason to panic, but a reason to be seen.
The Pinnacle way
A clinical AbilityScore® and any diagnosis are formed only at a Pinnacle Blooms Network centre, under qualified clinician care — never from an online article or a checklist. Genetic conditions like Rett need careful, calm, expert evaluation. Our team supports each child's strengths and everyday independence through [coordinated developmental therapy](/), structured assessment and review, and targeted occupational therapy for hand use and daily skills.Trusted sources
World Health Organization ICD-11 (Rett Syndrome, LD90.0); guidance from paediatric and developmental health bodies on X-linked genetic conditions and MECP2.Next step — If your child has lost skills she once had, [book a developmental check with a Pinnacle clinician](/) for calm, expert guidance.
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.
What to watch
In a girl who developed typically at first: a slowing or loss of hand skills, loss of babble or words, or new repetitive hand movements such as wringing or hand-to-mouth motions — these warrant a prompt developmental review.
Try this at home
Keep a short note or short videos of milestones your child reaches — when she points, babbles, picks things up. If skills she had seem to fade, those notes help a clinician see the pattern clearly.
Trusted sources
Developed by SETU Consortium · Pinnacle Blooms Network · Last reviewed 2026-06-10 · reviewed every 365 days
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.
Frequently asked
Can boys have Rett Syndrome at all?
Boys can carry a change in the MECP2 gene, but they very rarely show the classic Rett Syndrome picture seen in girls. Because boys have only one X chromosome, the same change usually causes a much more severe condition, often recognised in early infancy. Classic Rett Syndrome is described in girls.
Why does Rett Syndrome mainly affect girls?
Rett Syndrome is caused by a change in the MECP2 gene on the X chromosome. Girls have two X chromosomes, so a working second copy lets the typical Rett pattern develop. Boys have only one X and no second copy to balance the change, which usually leads to a different, more severe outcome.
My daughter is losing skills she once had — what should I do?
Loss of hand use, loss of babble or words, or new repetitive hand movements deserve a prompt developmental review. This is not a reason to panic, but it is a reason to be seen by a clinician who can assess calmly and guide next steps.