A type of gene mutation wherein the deletion (as well as addition) of (a number of) nucleotide (s) causes a shift in the reading frame of the codons in the mRNA, thus, may eventually lead to the alteration in the amino acid sequence at protein translation.
Lesson Summary. A deletion mutation occurs when part of a DNA molecule is not copied during DNA replication. This uncopied part can be as small as a single nucleotide or as much as an entire chromosome. The loss of this DNA during replication can lead to a genetic disease. Deletion Mutation and DNA. A deletion mutation occurs when part of a DNA molecule is not copied during DNA replication. This uncopied part can be as small as a single nucleotide or as much as an entire chromosome. Deletion is a type of mutation involving the loss of genetic material. It can be small, involving a single missing DNA base pair, or large, involving a piece of a chromosome. Definition from: Talking Glossary of Genetic Terms from the National Human Genome Research Institute.  A change in the genes or chromosomes of an organism. Mutations occurring in the reproductive cells, such as an egg or sperm, can be passed from one generation to the next. Most mutations have harmful effects, but some can increase an organism's ability to survive. mutation. n. 1. (Genetics) the act or process of mutating; change; alteration. 2. a change or alteration. 3. (Genetics) a change in the chromosomes or genes of a cell. Deletion on a chromosome. In genetics, a deletion (also called gene deletion, deficiency, or deletion mutation) (sign: δ) is a mutation (a genetic aberration) in which a part of a chromosome or a sequence of DNA is lost during DNA replication. Any number of nucleotides can be deleted, from a single base to an entire piece of chromosome. The smallest single base deletion mutations are believed occur by a single base flipping in the template DNA, followed by template DNA strand slippage, within the DNA polymerase active site. Medical Definition of MUTATION. 1. : a relatively permanent change in hereditary material involving either a physical change in chromosome relations or a biochemical change in the codons that make up genes; also: the process of producing a mutation. 2. : an individual, strain, or trait resulting from mutation.  frameshift mutation / frame-shift mutation; frameshift. A frameshift mutation is a genetic mutation caused by a deletion or insertion in a DNA sequence that shifts the way the sequence is read. A DNA sequence is a chain of many smaller molecules called nucleotides. Frameshift mutations arise when the normal sequence of codons is disrupted by the insertion or deletion of one or more nucleotides, provided that the number of nucleotides added or removed is not a multiple of three. Deletion mutation. Definition. noun. A type of gene mutation wherein the deletion (as well as addition) of (a number of) nucleotide (s) causes a shift in the reading frame of the codons in the mRNA, thus, may eventually lead to the alteration in the amino acid sequence at protein translation. Supplement. The second type of change results from the insertion of a base into, or its deletion from, the polynucleotide sequence. These mutations are all called sign mutations or frame-shift mutations because of their effect on the translation of the information of the gene. In a frameshift mutation, a nucleotide is added or deleted to the sequence and the decoding of the entire gene sequence will be radically altered and the amino acid sequence of the protein produced will also be very different. a mutation that results from insertion or deletion of a single nucleotide into, or from, the normal DNA sequence; because the genetic code is read three nucleotides at a time, all nucleotide triplets distal to the mutation will be one step out of phase and misread, and hence translated as different amino acids. 
http://study.com/academy/lesson/deletion-mutation-definition-examples-diseases.html http://www.ghr.nlm.nih.gov/glossary=deletion http://www.thefreedictionary.com/Deletion+mutation https://en.wikipedia.org/wiki/Deletion_%28genetics%29 http://www.merriam-webster.com/dictionary/mutation http://www.nature.com/scitable/definition/frameshift-mutation-frame-shift-mutation-frameshift-203 http://www.biology-online.org/dictionary/Deletion_mutation http://encyclopedia2.thefreedictionary.com/Deletion+mutation http://medical-dictionary.thefreedictionary.com/Deletion+mutation
definition of deletion mutation