Medical Dictionary Definitions A-Z List
Medical Dictionary Definitions A - Z - «M»:
Mutagen: Something capable of causing a gene-change. Among the
known mutagens are radiation, certain chemicals and some viruses. ...
Mutagenesis: The development and production of mutations in the genome....
Mutant: An individual with a mutant (changed) gene. ...
Mutation: A permanent change, a structural alteration, in the DNA or
RNA. In humans and many other organisms, mutations occur in DNA. However, in retroviruses like HIV, mutations occur in RNA which is the genetic material of retroviruses.
In most cases, such changes are neutral and have no effe...
Mutation, acquired: See: Acquired mutation.
Mutation, germline: A
heritable change in the
DNA that occurred in a germ cell (a cell destined to become an
egg or in the
sperm) or the
zygote (the conceptus) at the single-cell stage. When transmitted to a child, a germline mutation is incorporated in every cell of their body.
Mutation, hereditary: A heritable change in the DNA of a gene or chromosome in a cell destined to become an egg or a
sperm or the
zygote (the conceptus) at the single-cell stage. When transmitted to a child, an hereditary mutation is incorporated in every cell of their body.
Hereditary mutations ...
Mutation, missense: A genetic change involving the substitution of one base in the DNA for another which results in the substitution of one amino acid in a polypeptide for another. A missense mutation is a "readable" genetic message although its "sense" (its meaning) is changed. This is in contrast...
Mutation, nonsense: A mutation (a change) in a base in the DNA that prematurely stops the translation (reading) of messenger RNA (mRNA) resulting in a polypeptide chain that ends prematurely and a protein product that is truncated (abbreviated) and incomplete and usually nonfunctional.
Mutation, null: A mutation (a change) in a gene that leads to its not being transcribed into RNA and/or translated into a functional protein product.
For example, a null mutation in a gene that usually encodes a specific enzyme leads to the production of a nonfunctional enzyme or no enzyme at all....
Mutation, point: A single nucleotide base change in the DNA. A point mutation may consist of the loss of a nucleotide, the insertion of an additional nucleotide, or the substitution of one nucleotide for another.
The first point mutation discovered in humans involved the substitution of one nucleo...
Mutation, private: A rare mutation found usually only in a single family or a small population. (It is like a privately printed book.)...
Mutation, somatic: See: Somatic mutation.
Mute: A mute is a person who does not speak,
either from an inability to speak or an unwillingness to
speak. The term "mute" is specifically
applied to a person who, due to profound congenital (or
early) deafness, is unable to use articulate language and
so is deaf-mute. A mute in speech is a le...
Mutilating keratoderma: See: Vohwinkel syndrome....