Stem Cell Transplantation for Participants With Germline RUNX1 Associated Blood Cancers

Background: Some blood cancers can be caused by germline variants (changes) in a person s RUNX1 gene. Germline variants are genetic inherited changes a person is born with. Stem cell transplants are used to treat many diseases including blood cancers. Stem cell transplantation for patients with germline RUNX1 mutation driven blood cancers is standard of care and available in most major medical centers. The difference with this transplantation protocol is that it is prospective, only available to participants with germline RUNX1 variants and designed to determine the extent to which tailoring chemotherapy and supportive care medication doses for each individual patient may improve outcomes compared to data derived from retrospective transplantation protocols for patients with RUNX1 varinats which is less accurate. Objective: The primary objective of this protocol is to determine how tailored doses of chemotherapy and supportive care medications may improve disease free survival as compared to historical/expected disease free survival. Eligibility: People aged 4 to 70 years with blood cancer caused by a RUNX1 gene mutation. Other participants are also needed: (1) stem cell donors; (2) relatives who do not have a mutation in the RUNX1 gene; and (3) healthy volunteers. Design: Participants with blood cancer will be screened during approximately 1-3 months before transplatation. They will have blood tests and tests of their heart and lung function. A sample of bone marrow may be taken. A flexible tube (central line) will be inserted into a vein in participants' chest or lower neck. This line will remain in place during the hospitalization and be used to draw blood and administer drugs. These lines are almost always transitioned to a peripherally inserted central catheter (PICC) line at the time of hospital discharge. Participants will be inpatient for 4 to 5 weeks. They will receive drugs to prepare their body for the stem cell transplant. Some may also receive