Rare Diseases Clinical Trials Update: Week 19, 2026

Published May 8, 2026 — 5 trials covered

By Victor Lafforgue, Founder of TrialsAlert. Blog posts are AI-drafted from ClinicalTrials.gov source data and reviewed by the editorial team. See our editorial policy for details.

Safety and Efficacy of GS-100 Gene Therapy in Patients With NGLY1 Deficiency

This Phase 3 trial is testing GS-100 gene therapy in children aged 2 to 18 with NGLY1 Deficiency, a rare genetic disorder that affects many parts of the body. If successful, this treatment could address the root cause of the condition rather than just managing symptoms, offering hope for improved health outcomes. The study is currently active but not recruiting, with results expected after long-term follow-up.

Phase 3 Efficacy and Safety Study of GTX-102 in Pediatric Subjects With Angelman Syndrome (AS)

This study focuses on GTX-102, a new treatment aimed at improving cognitive function in children with Angelman Syndrome, a rare neurological disorder. By targeting the underlying genetic cause, the therapy has the potential to enhance quality of life for affected children. The trial is active but not recruiting and involves multiple countries, specifically enrolling pediatric patients with deletion-type Angelman Syndrome.

Long-term Extension of GTX-102 in Angelman Syndrome

This ongoing Phase 3 trial is evaluating the long-term safety and effectiveness of GTX-102 gene therapy in patients with Angelman Syndrome. The study is enrolling by invitation across several countries and aims to provide important information about lasting benefits and any side effects, which is vital for families considering this treatment option.

An Observational Study Comparing Delandistrogene Moxeparvovec (ELEVIDYS) With Standard of Care in Participants With Duchenne Muscular Dystrophy

This study compares a gene therapy called delandistrogene moxeparvovec, also known as ELEVIDYS, with standard treatments in children with Duchenne Muscular Dystrophy. The therapy may improve muscle strength and reduce the need for steroids, which can have significant side effects. The study is enrolling about 500 participants across the United States, offering a broad view of how this treatment works in real-world settings.

Pediatric Patients Aged 4 to 11 Years With APDS

This trial is testing leniolisib, an oral medication, in children aged 4 to 11 with activated phosphoinositide 3-kinase delta syndrome (APDS), a rare immune disorder. If successful, leniolisib could improve immune system function and overall quality of life by targeting a key part of the disease process. The study is ongoing and enrolling a small number of pediatric patients across several countries.

This week’s rare disease research highlights show steady progress in gene therapies and targeted treatments that aim to improve quality of life by addressing the causes of these conditions. Many of the ongoing trials involve children and focus on long-term safety and effectiveness, which are essential for families facing rare diseases. TrialsAlert subscribers received the full impact-classified briefing and doctor-ready report this week. Get weekly briefings at trialsalert.com.