• Z chromosome

    A sex chromosome in certain animals, such as chickens, turkeys, and moths. In humans, males are XY and females XX, but in animals with a Z chromosome, males are ZZ and females are WZ.

  • ZAP-70

    Zeta-chain-associated protein kinase 70. A member of the protein tyrosine kinase family, ZAP-70 is normally expressed in T cells and natural killer cells and has a critical role in the initiation of T-cell signaling. ZAP-70 is expressed in T cells and tumors of T-cell lineage. A high level of ZAP-70 expression appears restricted to T-cell […]

  • Zebra

    ‘When you hear hoof beats, think of horses, not zebras.’ For example, when someone develops a mild transient cough, a virus infection is the most logical and likely cause, and tuberculosis is a zebra.

  • Zygotic lethal gene

    A gene that is lethal (fatal) for the zygote, the cell formed by the union of a sperm (male sex cell) and an ovum (female sex cell). The zygote would normally develop into an embryo, as instructed by the genetic material within the unified cell. However, a zygotic lethal gene scotches prenatal development at its […]

  • Zygote intrafallopian transfer (ZIFT)

    A technique in which a woman’s egg is fertilized outside the body, then implanted in one of her fallopian tubes. This technique is one of the methods used to overcome infertility, the inability of couples to produce offspring on their own. First, the egg and the male sperm needed to fertilize it are harvested. Then […]

  • LCHAD deficiency

    Acute fatty liver of pregnancy (AFLP) has been found to be associated in some cases with an abnormality of fatty-acid metabolism. This abnormality is a deficiency of the enzyme long-chain-3-hydroxyacyl-CoA dehydrogenease (LCHAD). The mother (and father) have 50% of normal LCHAD activity and the fetus has no LCHAD activity. The metabolic disease in the baby’s […]

  • AGXT

    AGXT: A gene that provides instructions for making a liver enzyme called alanine-glyoxylate aminotransferase (AGXT). Inside liver cells, this enzyme is found in peroxisomes, structures that contain many different enzymes used to produce energy and the basic materials important for cellular activities. AGXT converts a compound called glyoxylate to glycine, an amino acid that is […]

  • Dose, absorbed

    Dose, absorbed: In radiology, the absorbed dose is the amount of energy that is deposited in any material by ionizing radiation. The unit of absorbed dose, the rad, is a measure of energy absorbed per gram of material. An alternative unit of absorbed dose is the gray. One gray equals 100 rads.

  • Axillary dissection

    Axillary dissection: Removal of a portion of the lymph nodes under the arm.

  • Left atrium

    The upper right chamber of the heart. The left atrium receives oxygenated blood from the lungs and pumps it down into the left ventricle which delivers it to the body.