Acetaminophen
A crystalline compound used instead of aspirin to relieve pain and reduce fever.

Acquired immune deficiency syndrome (AIDS)
A disease caused by the human immunodeficiency virus (HIV), which attacks the body's immune system, making it more prone to certain infections.

Adherence
The extent to which a patient continues treatment prescribed by their doctor under limited supervision.

Affinity chromatography
The separation of chemical substances and particles where the absorbent has a unique chemical affinity for a particular component of the passing solution.

Albumin
Any of numerous simple, heat-coagulable, water-soluble proteins that occur in blood plasma or serum, muscle, the whites of eggs, or milk. The manufacturing process of some factor replacement therapies includes albumin.

Aminocaproic acid
A drug useful in enhancing hemostasis when fibrinolysis contributes to bleeding.

Anamnestic response
Secondary immune response; any response of the immune system to an antigen including antibody production and/or cell-medicated immunity.

Anaphylactic reaction
Manifesting extreme sensitivity to foreign protein or other material. Hemophilia patients may experience this reaction after infusing with a factor concentrate.

Ancillary
Auxiliary, accessory, or secondary. When pertaining to hemophilia, ancillary medical supplies used during an infusion may include syringes, needles, medical tape, adhesives, alcohol swabs, gauze, and adhesive bandages.

Anemia
A condition in which the blood is either deficient in red cells, in hemoglobin, or in total volume.

Antibodies
Proteins that are produced in the body in response to an antigen and act specifically against the antigen in an immune response. Some persons with hemophilia may develop antibodies to infused factor.

Antigen
Any substance that is foreign to the body and as a result of coming in contact with appropriate cells, induces a state of sensitivity and/or immune responsiveness.

Arthropathy
Any disease affecting a joint; patients with severe hemophilia frequently experience spontaneous intra-articular hemorrhages, mainly in the ankles, knees, and elbows. Repeated episodes of hemarthrosis may cause irreversible arthropathy characterized by joint stiffness, chronic pain, and severely limited range of motion.

Aspirin
A derivative of salicylic acid used for relief of pain and fever. Aspirin and aspirin-containing products are contraindicated in individuals with hemophilia.

Assay
A specialized lab test used to determine the level of circulating factor VIII or IX in a person's body. The test results are reported as a percentage of normal levels.

Asymptomatic carrier (or just carrier)
A carrier (individual who possesses the gene) who shows no outward signs of a condition.