Background: Myelodysplastic syndromes (MDS) occur when the cells that make blood cells are abnormal. There are limited treatment options for MDS. Researchers want to learn more through this natural history study so they can develop better treatments.

Objective: To study the natural course of MDS and MDS/myeloproliferative neoplasms (MPN) and collect biological samples that can help researchers understand the disease.

Eligibility: People with suspected or confirmed MDS or MDS/MPN. Healthy donors are also needed. They can be people who are scheduled to donate bone marrow at NIH for a relative, or they may be providing bone marrow in another study.

Design: Participants will be screened with a medical history. Participants will have a physical exam. They will give blood and urine samples. They will discuss their symptoms, medications, and ability to perform their normal activities. They will complete surveys about how they are feeling. Participants will have a bone marrow biopsy. A needle will be inserted through a small cut. Bone marrow will be removed. A small piece of bone may be removed. Participants may have an optional skin biopsy. Participants may give optional saliva and stool samples. They may collect these samples at home and mail them to NIH. Participants may undergo optional apheresis. One or two needles or intravenous (IV) lines will be placed in their arm, neck, or groin veins. Blood will be removed. A machine will separate out the white cells. The rest of the blood will be returned to the participant. Participants will be contacted for follow-up once a year for up to 20 years. Healthy donors will have marrow collected for this study during their scheduled procedure with no follow-up.