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 […]

See Keratitis-ichthyosis-deafness syndrome.

two wings (lobes) attached to one another by a middle part called the isthmus. The thyroid uses iodine, a mineral found in some foods and in iodized salt, to make its hormones. The two most important thyroid hormones are thyroxine (T4) and triiodothyronine (T3). Thyroid stimulating hormone (TSH), which is produced by the pituitary gland, […]

Angina, Vincent: This is trench mouth, a progressive painful infection with ulceration, swelling and sloughing off of dead tissue from the mouth and throat due to the spread of infection from the gums. Certain germs (including fusiform bacteria and spirochetes) have been thought to be involved, but the full story behind this long-known disease is […]

Reluctance, avoidance, or fear of eating, drinking, or accepting sensation in or around the mouth. A familiar example of oral aversion is a baby’s refusal to breastfeed. Types of medical trauma such as prolonged intravenous or nasogastric feeding, gastrointestinal and respiratory disorders that may be associated with discomfort with eating may also contribute to the […]

GBV-C: GB virus C, a virus first identified in 1995 that is genetically related to the hepatitis C virus but which does not cause hepatitis and, in fact, is not known to be responsible for any disease. Infection with GB virus C (GBV-C) seems to be beneficial to HIV-infected patients. They enjoy longer survival if […]