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Genetic mutations are changes in your basic DNA composition. A genetic mutation is an alteration of base pair in your DNA. A single base change can create a devastating genetic disorder or a beneficial adaptation, or it might have no effect.



DNA Mutations Genetics Biology05:28

DNA Mutations Genetics Biology

A better understanding





This is the difference in a DNA strand that is normal vs. one which has sickle cell anemia (Cole-Strauss et al., 1996). One base change and genetically there is a big difference.


Sequence for Wild-Type Hemoglobin

ATG

GTG

CAC

CTG

ACT

CCT

GAG

GAG

AAG

TCT

GCC

GTT

ACT

Start

Val

His

Leu

Thr

Pro

Glu

Glu

Lys

Ser

Ala

Val

Thr

Sequence for Mutant (Sickle-Cell) Hemoglobin

ATG

GTG

CAC

CTG

ACT

CCT

GTG

GAG

AAG

TCT

GCC

GTT

ACT

Start

Val

His

Leu

Thr

Pro

Val

Glu

Lys

Ser

Ala

Val

Thr


(http://www.nature.com/scitable/topicpage/genetic-mutation-441)







Types of DNA Mutations and Their Impact


Class of Mutation

Type of Mutation

Description

Human Disease(s) Linked to This Mutation

Point mutation

Substitution

One base is incorrectly added during replication and replaces the pair in the corresponding position on the complementary strand

Sickle-cell anemia

Insertion

One or more extra nucleotides are inserted into replicating DNA, often resulting in a frameshift

One form of beta-thalassemia

Deletion

One or more nucleotides is "skipped" during replication or otherwise excised, often resulting in a frameshift

Cystic fibrosis

Chromosomal mutation

Inversion

One region of a chromosome is flipped and reinserted

Opitz-Kaveggia syndrome

Deletion

A region of a chromosome is lost, resulting in the absence of all the genes in that area

Cri du chat syndrome

Duplication

A region of a chromosome is repeated, resulting in an increase in dosage from the genes in that region

Some cancers

Translocation

A region from one chromosome is aberrantly attached to another chromosome

One form of leukemia

Copy number variation

Gene amplification

The number of tandem copies of a locus is increased

Some breast cancers

Expanding trinucleotide repeat

The normal number of repeated trinucleotide sequences is expanded

Fragile X syndrome, Huntington's disease


(http://www.nature.com/scitable/topicpage/genetic-mutation-441)







New research is being conducted with the development of equipment that can read base by base to determine genetic mutations (Sheffield et al., 2001). With the new technology scientists are unsure of what can be accomplished, many new challenges are to be faced.







Cole-Strauss, A., K, Yoon, Y. Xiang, B. Byrne, M. Rice, J. Gryn. W. Holloman.& E. Kmiec. (1996). Correction of the Mutation Responsible for Sickle Cell Anemia by an RNA-DNA Oligonucleotide. Science 273(5280). 1386-1389.





Sheffield, V. D. Cox, L. Lerman, & R. Meyers. (2001). Attachment of a 40-base-pair G + C-rich sequence (GC-clamp) to genomic DNA fragments by the polymerase chain reaction results in improved detection of single-base changes . Cross Mark. 86(1). 232-236.

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