Glossary of Terms

A condition in which the body does not have enough healthy red blood cells to carry oxygen throughout the body. Anemia is common in people with myelodysplastic syndromes (MDS) and often causes fatigue, weakness, dizziness, or shortness of breath.

Immature blood-forming cells normally found in the bone marrow. A small number of blasts is normal, but higher levels may indicate that MDS is progressing or that leukemia is developing.

The soft, spongy tissue inside bones where blood cells are made. Healthy bone marrow continuously produces red blood cells, white blood cells, and platelets.

A procedure used to collect a small sample of bone marrow, usually from the hip bone. The sample helps doctors diagnose blood disorders, monitor disease progression, and guide treatment decisions.

A lower-than-normal number of blood cells. Depending on the cell type affected, cytopenias may increase the risk of fatigue, infection, or bleeding.

A protein inside red blood cells that carries oxygen throughout the body. Hemoglobin levels are commonly measured to monitor anemia.

Blood cells that help stop bleeding by forming clots. Low platelet counts can increase the risk of bruising or bleeding.

Cells that carry oxygen from the lungs to the rest of the body.

Cells that help protect the body from infection. Certain blood cancers or treatments may lower white blood cell counts, increasing the risk of infection.

A procedure in which donated blood or blood components are given through a vein.

A change in the structure or number of chromosomes inside cells. Certain chromosome abnormalities can help diagnose MDS and guide treatment decisions.

The Molecular International Prognostic Scoring System, a tool that combines blood counts, chromosome abnormalities, and gene mutations to help predict disease outcome and classify risk for patients in MDS.

Medication used to remove excess iron from the body in persons with iron overload.

A buildup of excess iron that can occur after receiving many blood transfusions over time.

A form of MDS that is less likely to progress quickly to acute leukemia based on specific clinical factors. Although considered “lower risk,” it can still significantly affect quality of life and may require ongoing treatment.

A group of blood cancers in which the bone marrow does not produce enough healthy blood cells. MDS can affect red blood cells, white blood cells, platelets, or all three.

Abnormal developing red blood cells containing excess iron. Their presence may help classify certain types of MDS.

A way doctors estimate how MDS may behave over time using factors such as blood counts, genetic changes, and bone marrow findings.

Requiring regular red blood cell transfusions to manage anemia.

The buildup of scar tissue within the bone marrow that interferes with normal blood cell production.

The production of blood cells outside the bone marrow, most commonly in the spleen or liver.

A change in the JAK2 gene that causes blood-forming cells to grow and divide more than they should. It is the most common genetic mutation found in myelofibrosis (MF) and can help doctors diagnose and treat the disease.

A rare blood cancer in which scar tissue gradually builds up in the bone marrow, making it harder to produce healthy blood cells.

Myelofibrosis that develops on its own rather than evolving from another blood disorder.

A term used to describe disease that has either returned after treatment or has not responded adequately to treatment.

Myelofibrosis that develops after another blood disorder, such as polycythemia vera (PV) or essential thrombocythemia (ET).

An enlarged spleen. In myelofibrosis, the spleen often enlarges because it begins producing blood cells when the bone marrow can no longer do so effectively.

Any unwanted medical event that occurs during a clinical trial, whether or not it is related to the study treatment.

A research study that evaluates the safety and effectiveness of a new treatment, or a new way of using an existing treatment, in people.

The medical and other requirements that determine whether someone can participate in a clinical trial. Criteria may include age, diagnosis, prior treatments, lab results, and overall health.

The process of officially joining a clinical trial after meeting the eligibility criteria and providing informed consent.

The scheduled visits, tests, or communications that continue after treatment to monitor health, safety, and long-term outcomes.

The process of learning about a clinical trial before deciding whether to participate. Participants receive detailed information about the study’s purpose, procedures, potential risks, and possible benefits before signing a consent form.

A treatment that is still being studied and has not yet been approved for a specific use by regulatory authorities, such as the FDA or EMA.

The first stage of clinical testing in people. Phase 1 studies primarily evaluate a treatment’s safety, determine an appropriate dose, and identify potential side effects.

A study that continues to evaluate safety while examining how well a treatment works in people with a specific disease.

A larger study that compares an investigational therapy with the current standard of care or another treatment. Results from Phase 3 trials may support regulatory approval.

A substance or treatment that looks like the investigational therapy but contains no active medicine. Some clinical trials use a placebo for comparison, although many cancer trials compare a new treatment with the current standard of care instead.

The main outcome researchers measure to determine whether a clinical trial has met its objective.

A process that assigns participants to different treatment groups by chance. Randomization helps ensure study results are as fair and unbiased as possible.

The evaluations and medical tests performed before enrollment to determine whether someone meets the trial’s eligibility criteria.

Additional outcomes that provide more information about a treatment’s effects, such as symptom improvement, quality of life, or overall survival.

The treatment that is widely accepted by healthcare professionals as the current best approach for a particular disease or condition.

The hospital, clinic, or medical center where a clinical trial is conducted.