Medical Dictionary Definitions A-Z List
Medical Dictionary Definitions A - Z - «M»:
Maple syrup urine disease
Maple syrup urine disease: Hereditary disease due to
deficiency of an enzyme involved in amino acid metabolism, characterized by urine that smells like maple syrup. The three branched-chain amino acids: (leucine, isoleucine, and valine) cannot be metabolized (processed) and build up in the blood to ...
Mapping: Charting the location of genes on chromosomes. ...
Mapping, gene: The process of determining the relative positions of genes on a chromosome (or another piece of DNA) and the distances between the genes in linkage units or in physical units....
Marasmus: Wasting away, as occurs with children who have
kwashiorkor. Also called cachexia, is usually a result of protein and calorie deficiency. ...
Marburg disease: A severe form of hemorrhagic fever which affects both humans and non-human primates. Caused by a genetically unique zoonotic (that is, animal-borne) RNA virus of the filovirus family, its recognition led to the creation of this virus family. The four species of Ebola virus are the...
Marburg virus: The virus that causes Marburg hemorrhagic fever, a disease which affects both humans and non-human primates. Caused by a genetically unique zoonotic (that is, animal-borne) RNA virus of the filovirus family, its recognition led to the creation of this virus family. The four species ...
Marfan syndrome: An inherited disorder of connective tissue characterized by abnormalities of the eyes, skeleton, and cardiovascular system.
Myopia (nearsightedness) is the most common eye feature. Displacement of the lens from the center of the pupil occurs in over half of patients. There is an in...
Margaret Mead: See: Mead, Margaret....
Marie-Strümpell disease: A synonym for ankylosing spondylitis. Named for the French neurologist Pierre Marie (1853-1940) and the German neurologist whose full name was Ernst Adolf Gustav Gottfried von Str¨mpell (1853-1925).
See: Ankylosing Spondylitis....
Marijuana: A very common street and recreational drug that comes from the marijuana plant.
The plant that produces marijuana, as is well known, is the hemp plant cannabis sativa. The pharmacologically active ingredient in marijuana is tetra-hydro-cannabinol.
Marijuana is used to heighten percept...
Marinesco-Sjogren syndrome: A genetic
disorder characterized by very small stature, cerebellar ataxia (wobbliness), cataracts, muscle weakness, hypogonadism (low gonadal function), and developmental and mental retardation.
The disease is usually evident at birth because of hypotonia (floppiness). ...
Mark of Cain
Mark of Cain: The mark that God set upon Cain, the eldest son of Adam. According to the Book of Genesis in the Bible, God rejected Cain's grain offering while accepting the animal offering of his brother Abel. Out of jealousy, Cain murdered his brother and was compelled by God to wander the earth as...
Marker: A piece of DNA that lies on a chromosome so
close to a gene that the marker and the gene are inherited together.
A marker is thus an identifiable heritable spot on a chromosome.
A marker can be an expressed region of DNA (a gene) or a segment of
DNA with no known coding function. All that...
Marker chromosome: An abnormal chromosome that is
distinctive in appearance but not fully identified.
A marker chromosome is not a "marker" of a specific disease. It is a
marker chromosome merely in the sense that it can be distinguished
under the microscope from all of the normal human chromosom...
Marker gene: A detectable
genetic trait or segment of DNA that can be
identified and tracked. A marker gene can serve as a flag for another gene, sometimes called the target gene. A
marker gene must be on the same chromosome as the
target gene and near enough to it so that the two genes (the ma...