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 […]

Disease (there is more than one type) a condition of the eye that leads to progressive atrophy of the optic nerve often associated with increased pressure within the eye. Glaucoma can lead to blindness. Glaucoma is five times more likely to occur in Blacks than in Whites. Early detection of glaucoma is essential to the […]

Duchenne muscular dystrophy Becker muscular dystrophy limb-girdle muscular dystrophy facioscapulohumeral muscular dystrophy congenital muscular dystrophy oculopharyngeal muscular dystrophy distal muscular dystrophy Emery-Dreifuss muscular dystrophy and myotonic dystrophy. Muscular dystrophy can affect people of all ages. Although some forms first become apparent in infancy or childhood, others may not appear until middle age or later. Duchenne […]

A fracture in which the bone is sticking through the skin. Also called a compound fracture. Note that “comminuted fracture” in which the bone is fragmented is distinguished from a “compound fracture.”

alpha cells that make glucagon, which raises the level of glucose (sugar) in the blood; beta cells that make insulin; delta cells that make somatostatin which inhibits the release of numerous other hormones in the body; and PP cells and D1 cells, about which little is known. Degeneration of the insulin-producing beta cells is the […]

A form of muscular dystrophy (MD) in which weakness is usually confined to the anterior compartment (the front part) of the lower leg and, in particular, to the tibialis anterior muscle. The weakness usually starts at age 35 to 45, or even much later. Tibial MD is inherited in an autosomal dominant manner.