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 […]

Biermer’s anemia: A blood disorder caused by a lack of vitamin B12. Patients who have this disorder do not produce the substance in the stomach that allows the body to absorb vitamin B12. This substance is called intrinsic factor (IF). Biermer’s anemia, better known as pernicious anemia (PA), is characterized by the presence in the […]

Inflammation of the myocardium, the heart muscle. Myocarditis can be caused by a number of different conditions. The most common cause is infection of the heart muscle by a virus. The virus causes the initial heart muscle inflammation. After the initial viral infection subsides, the body’s immune system continues to inflict inflammatory damage on the […]

Along with smooth and cardiac muscle, one of the types of muscle tissue in the body. Skeletal muscle represents the majority of muscle tissue. It is the type of muscle that powers movement of the skeleton, as in walking and lifting.

A genetic form of angioedema due to C1-inhibitor deficiency (HAE-C1-INH). A rare, autosomal-dominant disease, HAE-C1-INH is characterized by recurrent attacks of marked, diffuse, nonpitting and nonpruritic skin swellings, painful abdominal attacks, and laryngeal edema. The extremities and the gastrointestinal tract are most commonly affected. Swelling of the upper respiratory mucosa poses the greatest risk because […]

A genetic skin disease characterized by scaly areas of skin that usually appear in childhood. The palms and soles are often affected. Areas that tend to be spared include the armpits, the insides of the elbows, and the skin behind the knee. Many people with ichthyosis vulgaris also have asthma, eczema, or hay fever. The […]