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.

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 […]

‘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.

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 […]

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 […]

One of several genetic disorders of the bone marrow that is evident at birth and characterized by a lack of neutrophils (a type of white blood cells that are important in fighting infection). Children with severe congenital neutropenia suffer from frequent bacterial (but not viral or fungal) infections. They are also at increased risk for […]

Surgery to treat varicose veins. The problematic veins are “stripped” out by passing a flexible device through the vein and removing it through an incision near the groin. Smaller tributaries of these veins also are stripped with this device or removed through a series of small incisions. Those veins that connect to the deeper veins […]

Fingerprint: 1. The characteristic dermal ridges on the finger. This is the original meaning of fingerprint. 2. The characteristic pattern of the peptide fragments of a protein that have been subjected to electrophoresis and, at a right angle, chromatography. Peptide fingerprinting was invented by Vernon Ingram in 1957. 3. The characteristic pattern of DNA fragments […]

A type of bacterium that comes in pairs and is shaped like a lancet (a surgical knife with a short wide two-edged blade). Pneumococcus is the leading cause of bacterial pneumonia and otitis media (middle ear infections) and an important contributor to bacterial meningitis. Pneumococcal infections are the most common invasive bacterial infections in children […]

Asbestos: A natural material made up of tiny fibers that is used as thermal insulation. Inhalation of asbestos fibers can lead to asbestosis and mesothelioma.