| Gene | Gene Product | Polymorphism | Effect of Polymorphism | References | 
| CYP1A1 | Aryl hydrocarbon hydroxylase | T3801C (m1)A2455G (m2) | UnknownNone
 | 131132
 | 
| CYP1A2 | Arylamine hydroxylase | C-164A | Decreased inducibility | 133,134 | 
| CYP2E1 | Ethanol-indudible P450 | 5’ flanking repeat region | Increased activity after ethanol exposure | 135,136 | 
| CYP3A4 | Steroid-inducible P450 | 5’ promoterA->G mutation
 | Unknown, perhapsexpression levels
 | 137,138 | 
| AHR | Aryl hydrocarbon receptor | G1721A | CYP1A1 inducibility? | 139 | 
| EPHX1 | Epoxide hydrolase | Tyr113HisHis139Arg
 | Altered protein stability | 140 | 
| NQ01 | NAD(P)H:quinone oxido-reductase 1 | C609T | Inactive enzyme | 88,141 | 
| NAT1 | N-Acetyl transferase 1 | Many alleles | Rapid vs. slow acetylation | 80 | 
| NAT2 | N-Acetyl transferase 2 | Many alleles | Rapid vs. slow acetylation | 80 | 
| SULT1A1 | Sulfotransferase | Arg213His | Low activity and lowthermal stability
 | 142 | 
| GSTM1 | Glutathione S-Transferase-µ | Deleted (null) allele(s) | No enzyme produced | 143 | 
| GSTP1 | Glutathione S-Transferase-π | Ile104ValAla113Val
 | Altered activity and substrate affinity | 144 | 
| GSTT1 | Glutathione S-Transferase-θ | Deleted (null) allele(s) | No enzyme produced | 145,146 | 
| PON1 | Paraoxonase | Arg192GlnMet55Leu
 Promoter point mutations
 | Change in Activity and substrate specificityChange inenzyme expression levels | 147-149 | 
| VDR | Vitamin D Receptor | RFLP in 3’ UTR; multiple point mutations | 3’ UTR = unknownknown effects for some point mutations | 148 | 
| HLA-DP ß1 | Antigen recognition protein | Lys69Glu | Change in CD4+ recognition | 58 | 
|  | Nucleotide Excision Repair (NER) enzyme system | Lys751Gln | Improved function
 Amino acid sequence change |  | 
| XRCC1 | Base Excision Repair (BER) | Arg399Gln | Unknown | 149 | 
| APE1 | Apurinic/apyrimidinic endonuclease 1 | Asp148Glu | Reduced endonuclease activity | 150 | 
| ALAD | d-Amino-levulinic Acid Dehydratase | G177C | Alleles 1and 2, 2 allele yields a more electronegative protein | 61 | 
| TLR4 | Type I trans-membrane protein | A896GD299G
 | Altered cell signal transduction by D299G after LPS exposure | 31 | 
| 
TNF   | Cytokine | G-308A | Altered transcriptional regulation | 151 |