SNP

한개의 염기서열의 차이를 이용하는 것을 말한다. 

1번 개체 ACCATG
2번 개체 ACTATG 

두 개체간의 염기서열의 차이를 이용하게 된다.
예를 들어 특정 질병에 잘 걸리는 집단과 잘 걸리지 않은 집단간의 유전자 차이를 비교, 질병의 원인을 규명혹은 마커 발견 할 때 유용하게 쓰이게 된다.  

scope Single base insertion/deletion variants (indels) would not formally be considered to be SNPs. 

Pronunciation SNP (pronounced 'S' 'N' 'P' or 'SNiP') 

of human SNPs Understand human DNA polymorphism, about 90% of which is single nucleotide polymorphism (SNP) 

SNPs could be bi-, tri-, or tetra-allelic polymorphisms. However, in humans, tri-allelic and tetra-allelic SNPs are rare almost to the point of non-existence, and so SNPs are sometimes simply referred to as bi-allelic markers (or di-allelic) 

The typical frequency with which one observes single base differences in genomic DNA from two equivalent chromosomes is of the order of 1/1000 bp = 0.1% 

cf) non-coding HLA regions show nucleotide diversity levels of 5–10%  Application Population genetics and linkage disequilibrium : The study of the genetic composition and inter-relationships between populations. The major research tool it uses is DNA polymorphism.   

Complex phenotypes and genome variation : Risks of major common diseases such as cancer, cardiovascular disease, mental illness, auto-immune states, and diabetes, are expected to be heavily influenced by the patterns of SNPs one possesses in certain key susceptibility genes yet to be identified. 

SNP based association studies : If a factor contributes an increased risk for disease occurrence, then that factor should be found at higher frequency in individuals with that disease compared to non-diseased controls

/> Brookes AJ, The essence of SNPs, Gene. 1999 Jul 8;234(2):177-86. [Database and Tools http://biocc.ngic.re.kr/Variome/Biowiki/index.php/Databases_and_Tools