Sickle Cell Anemia

KEY TERMS

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Amino acid

—An organic compound whose molecules contain both an amino group (-NH₂) and a carboxyl group (-COOH). One of the building blocks of a protein.

Anemia

—A condition in which the level of hemoglobin falls below normal values due to a shortage of mature red blood cells. Common symptoms include pallor, fatigue, and shortness of breath.

Bilirubin

—A yellow pigment that is the end result of hemoglobin degradation. Bilirubin is cleared from the blood by action of liver enzymes and excreted from the body.

Bone marrow

—A spongy tissue located in the hollow centers of certain bones, such as the skull and hip bones. Bone marrow is the site of blood cell generation.

Bone marrow transplantation

—A medical procedure in which normal bone marrow is transferred from a healthy donor to an ailing recipient. An illness that prevents production of normal blood cells—such as sickle cell anemia—may be treated with a bone marrow transplant.

Gel electrophoresis

—A laboratory test that separates molecules based on their size, shape, or electrical charge.

Globin

—One of the component protein molecules found in hemoglobin. Normal adult hemoglobin has a pair each of alpha-globin and beta-globin molecules.

Heme

—The iron-containing molecule in hemoglobin that serves as the site for oxygen binding.

Hemoglobin

—The red pigment found within red blood cells that enables them to transport oxygen throughout the body. Hemoglobin is a large molecule composed of five component molecules: a heme molecule and two pairs of globin molecules.

Hemoglobin A

—Normal adult hemoglobin which contains a heme molecule, two alpha-globin molecules, and two beta-globin molecules.

Hemoglobin S

—Hemoglobin that is produced in association with the sickle cell trait; the beta-globin molecules of hemoglobin S are defective.

Hydroxyurea

—A drug that has been shown to induce production of fetal hemoglobin. Fetal hemoglobin has a pair of gamma-globin molecules in place of the typical beta-globins of adult hemoglobin. Higher-than-normal levels of fetal hemoglobin can prevent sickling from occurring.

Iron loading

—A side effect of frequent transfusions in which the body accumulates abnormally high levels of iron. Iron deposits can form in organs, particularly the heart, and cause life-threatening damage.

Jaundice

—A condition characterized by higher-than-normal levels of bilirubin in the bloodstream and an accompanying yellowing of the skin and eyes.

Mutation

—A change in a gene's DNA. Whether a mutation is harmful is determined by the effect on the product for which the gene codes.

Nucleic acid

—A type of chemical that is used as a component for building DNA. The nucleic acids found in DNA are adenine, thymine, guanine, and cytosine.

Red blood cell

—Hemoglobin-containing blood cells that transport oxygen from the lungs to tissues. In the tissues, the red blood cells exchange their oxygen for carbon dioxide, which is brought back to the lungs to be exhaled.

Screening

—Process through which carriers of a trait may be identified within a population.

Sickle cell

—A red blood cell that has assumed a elongated shape due to the presence of hemoglobin S.

Sickle cell test

—A blood test that identifies and quantifies sickle cells in the bloodstream.