Safety and Preliminary Efficacy of TSHA-102 Gene Therapy in Pediatric Females Aged >2 to <4 Years With Rett Syndrome

Inclusion Criteria:

• Pediatric females between the ages of 2 and less than 4 years old.

• Participant has a clinical diagnosis of classic/typical Rett syndrome with adocumented pathogenic mutation of the methyl-CpG-binding protein 2 (MECP2) gene thatresults in loss of gene function.

• Participants must be willing to receive blood or blood products for the treatment ofan AE if medically needed.

• Participants and parent/caregiver must agree to reside within easy access to thestudy site prior to the baseline visit and at least 3 months after TSHA-102treatment.

Exclusion Criteria:

• Participant has another neurodevelopmental disorder independent of the MECP2loss-of-function mutation, or any other genetic syndrome with a progressive course.

• Participant has a history of brain injury that causes neurological problems or hadgrossly abnormal psychomotor development in the first 6 months of life.

• Participant has a diagnosis of atypical Rett syndrome or a MECP2 gene mutation thatdoes not cause Rett syndrome.

• Participant requires invasive ventilatory support.

Note: Other protocol defined inclusion/exclusion criteria may apply