Tuesday, Taysha Gene Therapies Inc ( TSHA ) released longer-term clinical data from the ongoing REVEAL Phase 1/2 adolescent and adult trial and initial clinical data from the REVEAL Phase 1/2 pediatric trial evaluating TSHA-102 in Rett syndrome.

Rett syndrome, caused by a pathogenic/likely pathogenic MECP2 mutation is estimated to affect between 15,000 and 20,000 patients in the U.S., EU, and U.K.

REVEAL Phase 1/2 Adolescent and Adult Trial showed sustained and new improvements observed across multiple clinical domains relative to baseline, as of 52 weeks post-treatment for patient one.

Durable improvements across consistent clinical domains in adult and pediatric patients, including motor skills, communication/socialization, autonomic function, and seizures, were observed.

Patient one gained the ability to sit unassisted for the first time in over a decade and move legs.

Patient two showed improved hand stereotypies for the first time since regression at age three and improved posture and stability, with being seizure-free for 8.5 months at 25% lower anti-seizure medication.

Related: Spinal Delivery Of Taysha’s Gene Therapy Shows Promise In Rare Childhood Neurodegenerative Disease.

TSHA-102 was generally well-tolerated, with no serious adverse events or dose-limiting toxicities as of the 52-week assessment post-treatment for patient one and the 36 weeks for patient two.

Initial data from the REVEAL Phase 1/2 Pediatric Trial showed improved Motor skills. Patient one, after 12 weeks post-treatment, was able to hold an object for three minutes vs. up to 12 seconds at baseline.

Patient two, after 8 weeks post-treatment, showed improved hand function and gait, speed, and stability when walking, with some new skills gained, including standing up from a chair and walking up a stair.

Price Action: TSHA shares are down 36.7% at $2.551 at last check Tuesday.