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 […]

Myelodysplastic syndrome, or myelodysplastic syndromes.

Fuchs endothelial corneal dystrophy: See: Corneal dystrophy, Fuchs endothelial.

TIPS stands for “transjugular, intrahepatic, portosystemic shunt.” It is a shunt (tube) placed between the portal vein which carries blood from the intestines to the liver and the hepatic vein which carries blood from the liver back to the heart. It is used primarily (but not exclusively) in patients with cirrhosis in which the scar […]

A pigment used as a test for acidity and alkalinity. Litmus paper turns red in acid and blue in an alkaline solution. Litmus is prepared from lichens like Roccella tinctoria. Figuratively, a litmus test is a decision in which a single factor is the determinant.

A neurological disorder marked by a sudden recurrent uncontrollable compulsion to sleep. Named for a French neurologist, JBE Gelineau (1859-1906). Also known as narcolepsy. The disorder is often associated with cataplexy (a sudden loss of muscle tone and paralysis of voluntary muscles associated with a strong emotion), sleep paralysis (immobility of the body that occurs […]