NNZ-2591

To Evaluate the Safety, Tolerability and Pharmacokinetics of Oral NNZ-2591 in Healthy Volunteers

An Open-Label Study of the Safety, Tolerability, and Pharmacokinetics of Oral NNZ-2591 in Angelman Syndrome

An Open-Label Study of Oral NNZ-2591 in Phelan-McDermid Syndrome (PMS-001)

An Open-Label Study of Oral NNZ-2591 in Pitt Hopkins Syndrome (PTHS-001)

An Open-Label Study of Oral NNZ-2591 in Prader-Willi Syndrome (PWS-001)

A Study of NNZ-2591 in Pediatric Participants With Phelan-McDermid Syndrome

An Open-label Study of NNZ-2591 in Pediatric Participants With Phelan-McDermid Syndrome