Telomere Biology Disorders

Background: Bone marrow failure diseases are rare. Much is known about the diseases at the time of diagnosis, but long-term data about the effects of the diseases and treatments are lacking. Researchers want to better understand long-term outcomes in people with these diseases. Objective: To follow people diagnosed with acquired or inherited bone marrow failure disease and study the long-term effects of the disease and its treatments on organ function. Eligibility: People aged 2 years and older who have been diagnosed with acquired or inherited bone marrow failure or Telomere Biology Disorder. First degree family members may also be able to take part in the study. Design: Participants will be screened with a medical history, physical exam, and blood tests. They may have a bone marrow biopsy and aspiration. For this, a large needle will be inserted in the hip through a small cut. Marrow will be drawn from the bone. A small piece of bone may be removed. Participants may also be screened with some of the following: Cheek swab or hair follicle sample Skin biopsy Urine or saliva sample Evaluation by disease specialists (e.g., lung, liver, heart) Imaging scan of the chest Liver ultrasounds Six-Minute Walk Test Lung function test Participants will be put into groups based on their disease. They will have visits every 1 to 3 years. At visits, they may repeat some screening tests. They may fill out yearly surveys about their medicines, transfusions, pregnancy, bleeding, and so on. They may have other specialized procedures, such as imaging scans and ultrasounds. Participation will last for up to 20 years. ...

The goal of this clinical trial is to learn if a combination therapy of deoxycytidine (dC) plus deoxythymidine (dT) is safe in patients with telomere biology disorders. The main questions it aims to answer are: * Is the therapy safe with tolerable side effects in patients with telomere biology disorders? * Are problems with the bone marrow or blood or lungs changed after 6 months of dC+dT treatment in patients with telomere biology disorders? Participants will: * Take study drug by mouth three times daily for 24 weeks * Make approximately 2 visits to Boston Children's Hospital during the 24 weeks: once at the beginning of treatment and once at the end of treatment. * Go to a lab for a blood draw an additional 6 times during treatment. * Have 9 phone calls with a research nurse, including one 4 weeks after treatment ends. * Keep a diary to track doses of study drug that were taken or missed.

This is a phase II trial of T cell receptor alpha/beta depletion (α/β TCD) peripheral blood stem cell (PBSC) transplantation in patients with inherited bone marrow failure (BMF) disorders to eliminate the need for routine graft-versus-host disease (GVHD) immune suppression leading to earlier immune recovery and potentially a reduction in the risk of severe infections after transplantation.