Glycogen storage disease type V and the most common type of glycogen storage disease. McArdle disease is an autosomal recessive disorder caused by mutations in the gene that encodes myophosphorylase, an enzyme that is essential for glycogenolysis. Exercise intolerance usually develops during childhood, along with pain, cramps, and fatigue in exercised muscle. These symptoms are more likely to be induced by brief, intense activities (such as weight lifting or sprinting) but can also occur after prolonged, low-intensity exercises (such as swimming or jogging). Severe muscle damage can lead to myoglobinuria (the release of myoglobin from muscle into the bloodstream) and renal failure. There is variation among patients with McArdle disease. Some patients become fatigued easily but have no clinically significant muscle cramps or pain, whereas others have with progressive atrophy and weakness of upper arm, and thigh muscles in late adulthood. In rare cases, McArdle disease is so severe it causes congenital weakness and progressive respiratory failure.
The Medical College Admissions Test, a test that is required of all applicants to medical school in the U.S. and Canada. The MCAT is “a standardized test used to assess applicants’ science knowledge, reasoning, and communication and writing skills.” The MCAT is administered by the Association of American Medical Colleges.
- McBurney's point
McBurney’s point is the most tender area of the abdomen of patients in the early stage of appendicitis. McBurney’s point is named after the 19th-century New York surgeon Charles McBurney (1845-1913) who was the leading authority in his day on the diagnosis and treatment of appendicitis. Dr. McBurney in 1889 showed that incipient appendicitis could […]
- McClintock, Barbara
(1902-1992) American geneticist who won the 1983 Nobel Prize in Physiology or Medicine for her discovery of genetic transposition, or the ability of genes to change position on the chromosome. Barbara McClintock was born in Hartford, Connecticut. Her family moved to Brooklyn, New York, in 1908. McClintock earned her B.S. and M.S. degrees in botany […]
- McCune-Albright syndrome
A genetic disorder of bones, skin pigmentation and hormonal problems with premature sexual development. Also called Albright syndrome or polyostotic fibrous dysplasia. In the syndrome, there is bone disease with fractures and deformity of the legs, arms and skull; pigment patches of the skin; and endocrine (hormonal) disease with early puberty (early menstrual bleeding, development […]
A peptide consisting of 2 or more amino acids. Amino acids make up polypeptides which, in turn, make up proteins.