Pitt Hopkins Syndrome

The goal of this clinical trial is to learn if MZ-1866 is a safe and tolerable treatment for children and adults with Pitt Hopkins Syndrome. To evaluate the safety of MZ-1866, the following will be evaluated: * frequency and severity of adverse events * physical exam, laboratory results and electrocardiogram findings Participants will: * receive a single dose of MZ-1866 by intracerebroventricular injection * be seen by the study physician and site staff periodically to assess changes to their health status * be periodically evaluated using neurodevelopmental tools Caregivers will: * be interviewed periodically about the health status and development of the participant * keep diaries and complete periodic questionnaires regarding participant symptoms

The study is an exploratory evaluation of the safety and efficacy of vorinostat in Pitt Hopkins syndrome. Each patient will be self-controlled in an adapted N-of-1 study design methodology with three treatment arms, including a 4-week placebo phase and two vorinostat dose arms, including every 8 weeks of daily dosing at a low dose of 80mg/m2/day and 8 weeks of a higher dose at 160mg/m2/day. Key objectives of the study include: * To confirm the safety and tolerability of oral vorinostat 80mg/m2/day and 160mg/ m2/day dose levels when administered to PTHS patients * To identify the nature and magnitude of treatment response to vorinostat, as measured by changes in clinical and laboratory parameters indicative of trend towards benefit, as well as changes in mRNA expression (transcriptome response) * Provide a data-driven justification for future study design and statistical analysis plan for subsequent clinical studies assessing safety and efficacy of vorinostat in PTHS

CoRDS, or the Coordination of Rare Diseases at Sanford, is based at Sanford Research in Sioux Falls, South Dakota. It provides researchers with a centralized, international patient registry for all rare diseases. This program allows patients and researchers to connect as easily as possible to help advance treatments and cures for rare diseases. The CoRDS team works with patient advocacy groups, individuals and researchers to help in the advancement of research in over 7,000 rare diseases. The registry is free for patients to enroll and researchers to access. Visit sanfordresearch.org/CoRDS to enroll.