Rett Syndrome
New Rett syndrome research, summarized each month in plain language.
2026 so far: So far in 2026 (January-September), real-world reports on trofinetide described how long people tend to continue it and how often gastrointestinal side effects occur. Small uncontrolled studies also suggested fenfluramine may reduce drug-resistant seizures. Read the 2026 review
We also cover clinical trials.
Yearly update
2026 so far
- Trofinetide in real life. Evidence shifted from side-effect signals to real-world persistence patterns.
- Fenfluramine for seizures. Small case series expanded into a small open-label study.
- Daily life priorities. Reports increasingly centered outcomes on family priorities and function.
- Tracking symptoms better. Measurement work moved toward shorter, more usable recordings and clearer trajectories.
- Future treatment ideas. Multiple lab and animal approaches targeted MeCP2 or breathing/motor pathways.
New
September 2026
- Seizure add-on drug. Adding fenfluramine was linked to fewer seizures in a small study.
- Sleep and breathing. Sleep and daytime breathing seemed better, but without a comparison group.
- Bone density and surgery. Lower CT bone density was linked to less spine curve correction.
August 2026
- Adult trofinetide use. Adult records showed trofinetide use in only a minority.
- Stomach side effects. Clinicians stressed managing diarrhea and vomiting with trofinetide.
- Daily function tracking. Experts stressed baseline measures and follow-up of daily abilities.
- Sleep-breathing concerns. Caregiver surveys flagged ongoing sleep-related breathing concerns.
July 2026
- Trofinetide use. In claims data, most ages 2 to 4 stayed on trofinetide.
- Early stop signals. Earlier stopping was linked to prior feeding and breathing problems.
- Cleaner EEG data. Automated EEG cleanup kept more usable brain-wave recordings.
June 2026
- Trofinetide continuation. About half continued trofinetide in US prescription data.
- Who received trofinetide. Use was mostly in younger patients seen by specialists.
- PTP1B mouse results. PTP1B blocking improved movement and breathing in Rett mice.
May 2026
- Trofinetide: benefits vs side effects. In routine care, families often reported some gains on trofinetide, but side effects were also common.
- Speech-language therapy experience. Families described speech-language therapy quality as closely tied to available resources and therapist empathy.
- Hand behaviors and age. Hand behaviors were a prominent concern in caregiver reports, and links with age were not clear in that sample.
- Early lab and animal findings. Several lab and animal studies shifted Rett-like measures, but these results are not yet proven in people.
April 2026
- Emotional well-being in families. In one survey study, emotional well-being was the lowest-scoring area for families.
- Symptoms across age. In a caregiver questionnaire study, older age was linked with lower scores for breathing abnormalities and hand stereotypies.
- MECP2 mutation effects in organoids. In patient-derived brain organoid models, different MECP2 mutations were associated with differences in neuron activity and network connectivity.
- Possible symptom pathways in mice. Mouse studies connected breathing, gut movement, and swallowing-related features to specific biological signaling pathways.
March 2026
- Seizure rescue tolerability. In a small Rett subgroup, diazepam nasal spray appeared tolerable, with side effects similar to the broader pediatric group in the same study.
- Genetic testing before classic signs. Broad genetic testing identified MECP2-related Rett in some people before they met classic clinical criteria.
- MeCP2 increase in lab models. Changing MECP2 splicing increased MeCP2 levels in laboratory models, but this has not been shown in people.
- Injectable trofinetide (preclinical). A redesigned injectable form of trofinetide increased drug exposure in preclinical testing.
February 2026
- Small seizure case series. In a four-child report, fenfluramine was linked to large seizure reductions in three children with drug-resistant epilepsy, but the sample is too small to know how typical this is.
- Mouse breathing and seizure signals. Several Rett mouse studies linked different lab approaches to fewer breathing pauses and less seizure-like brain activity, which mainly helps guide what to test next.
- Daily symptoms and family impact. Human observational studies described common sleep, gastrointestinal, and epilepsy symptoms and linked poorer sleep with worse family well-being measures.
January 2026
- Behavior questionnaires over time. Across long-term follow-up, behavior questionnaire scores often trended lower with age, translated versions generally performed well, and different raters sometimes gave different scores.
- Timing of skill gain and loss. Most skills were reported as gained in early childhood, and when loss was reported it often occurred within about two years of the skill first appearing.
- Trofinetide side effects timing. Real-world reports most often described gastrointestinal side effects (especially diarrhea), with many reports occurring in the first month after starting.
- MeCP2 signals in models. Lab and mouse studies linked MeCP2 changes to altered inhibitory signaling and pain responses over time, and cell experiments suggested MeCP2 can bind certain histone marks as well as DNA.
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