Autosomal dominant: A pattern of inheritance in which an affected individual has one copy of a mutant gene and one normal gene on a pair of autosomal chromosomes. (In contrast, autosomal recessive diseases require that the individual have two copies of the mutant gene.) Individuals with autosomal dominant diseases have a 50-50 chance of passing the mutant gene and therefore the disorder on to each of their children. Examples of autosomal dominant diseases include Huntington disease, neurofibromatosis, and polycystic kidney disease.
Achromatopsia: A hereditary disorder of sight due to a lack of cone vision – that type of vision provided by the cone photoreceptors in the retina. In the normal eye, there are some 6 million cone photoreceptors; they are located largely in the center of the retina. Lacking cones, persons with achromatopsia have to rely […]
- Acid deposition
Acid deposition: A complex chemical and atmospheric phenomenon that occurs when emissions of sulfur and nitrogen compounds and other substances are transformed by chemical processes in the atmosphere and then deposited on earth in either wet or dry form. The wet forms, popularly called acid rain, can fall to earth as rain, snow, or fog. […]
- Acid indigestion
- Acid phosphatase
Acid phosphatase: An enzyme that acts to liberate phosphate under acidic conditions and is made in the liver, spleen, bone marrow, and prostate gland. Abnormally high serum levels of acid phosphatase may indicate infection, injury, or cancer of the prostate.
- Acid rain
Acid rain: Rain or precipitation that contains elevated levels of hydrogen ions. Elevated hydrogen levels decrease pH levels. Decreased pH level creates an acidic atmosphere. Acid rain results from the combination of fossil fuel emissions and water in the atmosphere. The environmental effects of acid rain include the acidification of lakes and streams, damage to […]