A  B  C  D  E  F  G  H  I  J  K  L  M  N  O  P  Q  R  S  T  U  V  W  X  Y  Z

A

allele
One of two or more genes that occupy the same place on a specific chromosome¹⁵

anaphylactic reaction
Severe, potentially life-threatening allergic reaction to a foreign substance; such a reaction occurs in a small number of hemophilia patients after infusion with clotting factors.¹⁶

anticoagulant
A substance that delays or prevents blood clotting¹⁵

B

bleeding time
The time required to stop bleeding from an incision under controlled conditions; one of the screening tests used to evaluate the body's ability to stop bleeding.¹⁷ Bleeding time can be normal in patients with hemophilia.

blood-borne pathogens
Substances present in the blood and carried by it throughout the body. Blood-borne substances, such as viruses, can be transmitted to others through blood transfusions, needle sharing, and other activities.¹⁶

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C

carriers
Individuals who carry a gene for a condition but do not have the condition themselves^16,18

Christmas disease
Hemophilia B, or factor IX deficiency; it is named for the first person diagnosed with this form of hemophilia⁴

chromosome
Structures inside human cells that contain genes that are passed down through families¹⁶

clot
A soft, insoluble mass formed when blood coagulates or gels¹⁵

clotting factors
Proteins needed to make blood clot³

coagulation
The process by which the blood is transformed from a liquid to a gel, which leads to the formation of a clot¹⁶

coagulation factor
A protein that is involved in the process of coagulation; also called a clotting factor¹⁶

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D

deoxyribonucleic acid (DNA)
A nucleic acid found in living cells; DNA contains an organism's genetic information.¹⁵

dominant
A genetic trait that is expressed to the exclusion of a contrasting (recessive) genetic trait¹⁵

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F

factor VIII
A factor in blood clotting, a deficiency of which is associated with hemophilia A¹

factor IX
A factor in blood clotting; a deficiency of factor IX causes hemophilia B.¹

G

gene
A segment of DNA that transmits genetic (hereditary) information¹⁶

H

hemarthrosis
Bleeding into a joint, often causing swelling and pain^6,15

hematuria
Presence of blood in the urine¹⁶

hemophilia
A general term that describes certain inherited bleeding disorders caused by a deficiency of one of the factors necessary for blood clotting¹

hemophilia A
A type of hemophilia caused by a deficiency of factor VIII; also called classic hemophilia⁴

hemophilia B
A type of hemophilia in which bleeding occurs because of a deficiency of factor IX; also called Christmas disease⁴

hemorrhage
Excessive bleeding¹⁶

hemostasis
The arrest of bleeding¹⁶

heparin
A complex organic acid found especially in lung and liver tissue that prevents blood clotting and is used in the treatment of thrombosis¹⁵

hepatitis
A disease of the liver that can cause swelling of and possible damage to the liver.¹⁶ Hepatitis can have multiple causes, including infection by certain viruses such as hepatitis A, B, or C.

HIV (human immunodeficiency virus)
The virus that causes acquired immune deficiency syndrome (AIDS)¹⁶

I

infusion
Introduction of substances into the bloodstream through a vein¹⁶

inherited
Passed down through a family via the genes¹⁵

inhibitor
A substance that impedes certain activities in the body (for example, physiological, chemical, or enzymatic action). In hemophilia patients this may refer to an antibody that is specific for and disrupts the function of a clotting factor.^15,16

L

lyophilized
Freeze-dried⁴

P

parvovirus B19
A very small virus that can cause a common childhood infection¹⁵

pathogen
Any virus, bacteria, or other microorganism or infectious agent that causes disease¹⁶

plasma
The liquid portion of blood that contains nutrients, dissolved salts, gases, albumin, clotting factors, wastes, and hormones¹⁶

platelets
Cell fragments in the bloodstream that are essential for blood clotting¹⁶

prevention
Factor infusions given in addition to an on-demand or prophylactic schedule, often prior to a period of increased bleeding risk such as exercise⁴

prophylaxis
In hemophilia, the regularly scheduled injection of clotting factor to prevent bleeding⁴

R

recessive
A trait that is expressed only if both genes in a gene pair share the trait¹⁵

recombinant DNA
Pieces of DNA that have been isolated from one cell, cut at definable points, and "recombined" or inserted into the DNA of a different cell. Cells containing recombinant DNA can be engineered to produce large amounts of a protein.¹⁵

S

serum
The clear portion of fluid separated from its more solid elements such as cells, especially the clear portion (blood serum) that separates during blood clotting¹⁶

V

von Willebrand factor
A blood protein believed to stabilize factor VIII and transport it to bleeding sites¹⁶

X

X-linked genes
Genes that are present on the X chromosome¹⁶

The health information contained herein is provided for educational purposes only and is not meant to replace personal discussions between health care providers and patients. All decisions about patient care must be made with a health care provider who can assess the special needs of each individual patient.