There is a change in DNA sequence (expressed SNP, a slice, scissors s) single nucleotide polymorphisms to one base generator -, G T, or C, – pairs or members of the species (shared sequence or other) genome It is a different human chromosomes between. For example, two order DNA fragment includes AAGCCTA of AAGCTTA, the difference of a single nucleotide from different individuals. In this case, I say that the two alleles are present. SNP general all have alleles only almost 2. Genomic distribution nonuniformity of the SNP, the SNP, or occurs in non-coding regions than code area more frequently than usual, in general, act as natural selection, and the allele SNP most advantageous genetic adaptation lock. Other factors, such as mutation rate and gene recombination such is able to determine the concentration of SNP.  Strong predictor of microsatellite AT density SNP is in the region of low GC and density SNP paths long (AT) of (o) is greatly reduced, especially: that is provided by the presence of microsatellite SNP density I will not take into account the trend found.

In the population, can be assigned to less frequent allele SNP is – sites that are observed in groups that were given, the allele frequency of the lowest. This is a low allele frequency of two for the single nucleotide polymorphisms only. Because there is a difference between the human population, SNP allele that is common in ethnic groups and one geography, may be rare much different. Genetic variation of these between individuals, is performed DNA assay, above which (especially in non-coding part of the genome) was used in forensics. In addition, the genetic variation of these, underlying the differences in the sensitivity of our disease. The severity of the disease, the method also body responds to the treatment, which is a manifestation of genetic mutation. For example, mutations have been associated with an increased risk of Alzheimer’s disease in Besuapo (apolipoprotein E) gene.

transcriptional Important genes of two of U~eineru that shows the effect of phenotype and function of polymorphism is a gene XPC and XPD. Further, in addition to the activity of other, XPD, also known as ERCC2 serves the detection of DNA surrounding the lesion site during the NER. The study, are associated with a genetic predisposition to several types of cancer (A> T) is (Lys751Gln) exon 23 (G> A) and (Asp312Asn) polymorphism in exon 10 have shown that . Responsibility XPC gene of the protein that recognizes the DNA between the early part of Pasuabuneru. This gene, may have a polymorphism in exon 15 of the SNP that is associated with the risk of cancer as well as intron 9. The study, that skin cancer, breast cancer, polymorphism insertion / deletion allele, poly (AT) XPC intron 9 is associated with an increased risk of prostate cancer in a population of northern India in particular has been shown.

Hereditary cancer, research of xeroderma pigmentosum have identified several genes that encode proteins in NER path are two of them there XPD and XPC. It is caused by a homozygous deficiency of (TC-NER) repair of UV DNA damage that increases the risk of skin cancer patients, more than 1000 times XP. In heterozygous patients, the risk of cancer is sporadic, but may be provided on the basis of the analytical evaluation of the genetic polymorphism associated with DNA repair XP from purified lymphocytes. After the recurrence rate of research and III colon cancer, XPD (ERCC2) polymorphism 2251A> C was correlated with chemotherapy after early recurrence significantly stage II and high-risk. The effect of channel gene polymorphism, studies have shown that it is an additive the presence of cancer have a higher frequency of mutants in the risk significantly.