FPDMM

Background: Genes tell the body and its cells how to work. Familial platelet disease (FPD) or FPD with associated malignancies (FPDMM) is caused by a variant in the gene RUNX1. People with this disease may have problems with their blood and bleed for a long time when they are injured. Researchers want to learn more about RUNX1 variants and FPD. Objective: To learn more about FPD in people with RUNX1 variants to lead to better diagnosis, monitoring, and treatment. Eligibility: People any age with a suspected or confirmed RUNX1 variant People who have a family member with the variant Design: All participants will be screened with a phone call and a blood, saliva, or cheek cell sample. Participants with a suspected or confirmed variant will have 1 visit. It will last about 2 days. They will then have visits at least once a year. Visits will include: * Medical history and physical exam * Blood tests or saliva sample * Possible skin biopsy: A small piece of the participant s skin will be removed. * Bone marrow aspiration or biopsy: The participant s bone marrow will be removed by needle from a large bone such as the hip bone. * Possible apheresis: Blood will be removed from t