Atopic: A predisposition toward developing certain allergic hypersensitivity reactions. Atopy may have a hereditary component, although contact with the allergen must occur before the hypersensitivity reaction can develop.
- Atopic dermatitis
A skin disease characterized by areas of severe itching, redness, scaling, and loss of the surface of the skin. Atopic dermatitis is the most common of the many types of eczema. Atopic dermatitis is frequently associated with other allergic disorders, especially asthma and hay fever. A defect of the immune system within the skin has […]
Atopy: The genetic tendency to develop the classic allergic diseases — atopic dermatitis, allergic rhinitis (hay fever), and asthma. Atopy involves the capacity to produce IgE in response to common environmental proteins such as house dustmite, grass pollen, and food allergens. From the Greek atopos meaning out of place.
Atresia: Absence of a normal opening, or failure of a structure to be tubular. Atresia can affect many structures in the body. For example, esophageal atresia is a birth defect in which part of the esophagus is not hollow, and with anal atresia, there is no hole at the bottom end of the intestine.
- Atresia, anal
Atresia, anal: Congenital absence of an opening at the bottom end of the intestinal tract. Also called imperforate anus. Occurs in about 1 in 5,000 births. It is corrected by surgery. Atresia refers to the absence of a normal opening.
- Atresia, aortic
Atresia, aortic: Congenital absence of the normal valvular opening from the left ventricle of the heart into the aorta. “Atresia” here refers to the absence of a normal opening.