Pharmacogenetics research on chemotherapy resistance in colorectal cancer over the last 20 years

Table 4 Selected common polymorphisms of MDR1, GSTP1, ERCC1, ERCC2, XRCC1 genes and their potential impact on functioning of proteins related to OX pharmacology

dbSNP rs cluster ID	Type of polymorphism	Function	Ref.
Multidrug resistance 1 (MDR1, ABCB1) (OMIM #171050)
rs1128503	SNP		[152,296,318,485]
	1236C>T	Synonymous, effect unknown
http://www.ncbi.nlm.nih.gov/SNP/snp_ref.cgi?rs = 1128503
rs2032582	SNP		[152,296]
	2677G>T/A	Ser893Ala or Ser893Thr, the GG genotype carriers have the highest while the AT genotype carriers have the lowest levels of ABCB1 expression
http://www.ncbi.nlm.nih.gov/SNP/snp_ref.cgi?rs = 2032582
rs1045642	SNP		[152,296,350,485]
	3435C>T	Synonymous, TT genotype carriers have lower intestinal ABCB1 expression
http://www.ncbi.nlm.nih.gov/SNP/snp_ref.cgi?rs = 1045642
Glutathione S-transferase π (GSTP1) (OMIM #134660)
rs1138272	SNP		[311,477]
	341C>T	Ala114Val, altered enzyme kinetics, altered toxicity
http://www.ncbi.nlm.nih.gov/SNP/snp_ref.cgi?rs = 1138272
rs1695	SNP		[51,180,311-329,467,477]
	313A>G	Ile105Val, decreased enzymatic activity, altered toxicity
http://www.ncbi.nlm.nih.gov/SNP/snp_ref.cgi?rs = 1695
Excision repair cross-complementation group 1 (ERCC1) (OMIM #126380)
rs11615	SNP		[51,313,344,345,357,486]
	354T>C	Synonymous, decreased transcriptional activity of ERCC1
http://www.ncbi.nlm.nih.gov/SNP/snp_ref.cgi?rs = 11615
rs3212948	SNP		[487]
	321+74C>G	Intronic SNP (intron 2), protective effect of the C allele to cancer risk
http://www.ncbi.nlm.nih.gov/SNP/snp_ref.cgi?rs = 3212948
Excision repair cross-complementation group 2 (ERCC2, XPD) (OMIM #126340)
rs13181	SNP		[51,313,336,337,350,351,353,356,357,486]
	2251A>C	Lys751Gln, the Gln allele is associated with a higher DNA adduct level or lower DNA repair capacity
http://www.ncbi.nlm.nih.gov/SNP/snp_ref.cgi?rs = 13181
rs1799793	SNP		[313,336,337,353]
	862G>A	Asp312Asn, lower DNA repair capacity for the Asn allele than the Asp allele
http://www.ncbi.nlm.nih.gov/SNP/snp_ref.cgi?rs = 1799793
X-ray cross complementation factor (XRCC1) (OMIM #194360)
rs25487	SNP		[51,313,349,350,361-364,486]
	1196A>G	Arg399Gln, reduced base excision repair function for Gln allele than the Arg allele
http://www.ncbi.nlm.nih.gov/SNP/snp_ref.cgi?rs = 25487

SNP: Single nucleotide polymorphism.