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 […]

Alveolar hydatid disease: Abbreviated AHD. A parasitic disease caused by the larval stage of a microscopic tapeworm Echinococcus multilocularis. AHD is found worldwide, mostly in northern latitudes. in central Europe, Russia, China, Central Asia, Japan, and North America. In North America E. multilocularis is found primarily in the north central region from eastern Montana to […]

Enuresis: Involuntary urination, which may be caused by a variety of factors. These include disorders of the kidneys, bladder, or ureter and/or poor control of the muscles that control the release of urine. Enuresis is also occasionally associated with neurological disorders, such as Tourette’s syndrome, particularly in children. Nighttime (nocturnal) enuresis may be related to […]

Delivery, vertex: In a vertex delivery, the top of the baby’s head comes first. The vertex here refers to the top of the head. The word “vertex” in Latin means a “whirlpool, whirlwind, top of the mountain, or the top of the head.” Why “top of the head”? Because the hairs on the top of […]

Angioedema, hereditary: A genetic form of angioedema. (Angioedema is also referred to as Quinke’s disease.) Persons with it are born lacking an inhibitor protein (called C1 esterase inhibitor) that normally prevents activation of a cascade of proteins leading to the swelling of angioedema. Patients can develop recurrent attacks of swollen tissues, pain in the abdomen, […]

developing assays, purifying macromolecules, documenting a discovery by many approaches, and writing clear manuscripts describing what is known and what remains to be investigated. As he later recalled, his three years at NIH were critical in his scientific education. In 1972, Prusiner began a residency at UCSF in the department of neurology, where he became […]