Low-Dose Danazol for the Treatment of Telomere Related Diseases

Background: DNA is a structure in the body. It contains data about how the body develops and works. Telomeres are found on the end of chromosomes in DNA. Some people with short telomeres or other gene changes can develop diseases of the bone marrow, lung, and liver. Researchers want to see if low doses of the hormone drug danazol can help. Objective: To study the safety and effect of low dose danazol. Eligibility: People ages 3 and older with a telomere disease who have either very short telomeres and a specific gene change. They must also show signs of aplastic anemia, lung, or liver disease. Design: Participants will be screened in another protocol. Participants will have: * Medical history * Physical exam * Blood tests * Lung exam. They will breathe into an instrument that records the amount and rate of air breathed in and out over a period of time. 6-minute walking test. * Abdominal ultrasound and liver scan. These tests use sound waves to measure the fibrosis in the liver. Some participants will have: * Pregnancy test * Small sample of the liver removed * Bone marrow biopsy. The bone will be numbed and a small needle will take a sample of the marrow. All participants will have hormone levels checked. All child participants will see a pediatric endocrinologist. Children may need to have a hand x-ray. We will monitor patients for 6 months before starting danazol. Participants will take danazol by mouth twice a day for 1 year. Participants must return to the clinic at 6 months and 12 months while on danazol and 6 months after stopping it. They will have blood and urine tests, a lung exam, abdominal ultrasound, and liver scan.

NCT Number	NCT03312400
Lead Sponsor	National Heart, Lung, and Blood Institute (NHLBI)
Conditions	Telomere Disease
Enrollment	18 participants
Start Date	2018-02-08
Primary Completion	2025-10-31 (estimated)
Study Completion	2025-10-31 (estimated)
Updated on ClinicalTrials.gov	2026-06-25