1. Nucleotides (molecules containing sugar, nitrogen containing purine and pyrimidine bases, and a phosphate group) are the building blocks of DNA

2. Codon (units of three adjacent nucleotides) Each codon specifies one amino acid Arrangement of codons in the DNA (organ specific) Transcription into messenger RNA (mRNA) Determination of the sequence of amino acid that forms a particular protein The number of possible biosynthetic permutations is very high if one considers that a typical protein can be made of 500 amino acids and that one of these may be occupied by any one of 20 different amino acids Proteins: Make up the cell cytoskeleton Directed movement of molecules throughout the cell Pump nutrients and ions across the membranes Serve as receptor sites for hormones that finitely adjust the functions of the cell according to changing bodily needs A group of proteins regulates gene activities by binding to DNA and activating or repressing gene transcription

3. Some serve as carrier molecules like hemoglobin, the body’s oxygen carrier. Some small proteins (peptides) are secreted by cells as neurotransmittersor hormones like insulin. These hormones and other peptide molecules hold enormous power. Because they can act on numerous specific cell surface receptors, they can influence virtually all bodily functions from the nervous system to immune system Their selectivity, potency, and often-desired evanescent effects on selective target cells make them enormously attractive as magic bullets (Paul Ehrlich) The concept that genetic information flows from DNA to RNA to proteins has become a fundamental milestone of modern biology

4. Pharmacogenomics Pharmacogenomics is the study of how an individual's genetic inheritance affects the body's response to drugs. The term comes from the words pharmacology and genomics and is thus the intersection of pharmaceuticals and genetics.

5. Effect on drug absorption MDR1 gene encodes P-glycoprotein (P-gp) a large transmembrane protein that is an integral part of the blood- brain barrier and mucosal barriers P-gp functions as a drug-efflux pump effluxing a variety of drugs P-gp is also involved in imparting resistance to multiple structurally unrelated chemotherapeutic agents MDR1 has been mapped to chromosome 7 Chan et al. (1991) demonstrated that the measurement of P-gp immunohistochemically in tumor samples in children with neuroblastoma is helpful in predicting the success or failure of therapy

6. Hoffmeyer et al. (2000) found a significant correlation between a polymorphism in exon 26 of MDR1, 3435C-T, with expression levels of MDR1 People who are homozygous for the 3435T allele of MDR1 have on average substantially lower intestinal P-gp expression than those homozygous for the C allele 83% of west africans (Ghanaians) studied and 61% of African Americans were homozygous for the C allele, whereas only 26% Caucasians and 34% Janpanese showed this genotype (P<0.0001)

7. Influence on drug elimination The cytochrome P450 (CYP) family of liver enzymes is responsible for breaking down more than 30 different classes of drugs. DNA variations in genes that code for these enzymes can influence their ability to metabolize certain drugs. Less active or inactive forms of CYP enzymes that are unable to break down and efficiently eliminate drugs from the body can cause drug overdose in patients. Today, clinical trials researchers use genetic tests for variations in cytochrome P450 genes to screen and monitor patients. In addition, many pharmaceutical companies screen their chemical compounds to see how well they are broken down by variant forms of CYP enzymes

8. Another enzyme called TPMT (thiopurine methyltransferase) plays an important role in the chemotherapy treatment of a common childhood leukemia by breaking down a class of therapeutic compounds called thiopurines. A small percentage of Caucasians have genetic variants that prevent them from producing an active form of this protein. As a result, thiopurines elevate to toxic levels in the patient because the inactive form of TMPT is unable to break down the drug. Today, doctors can use a genetic test to screen patients for this deficiency, and the TMPT activity is monitored to determine appropriate thiopurine dosage levels.

9. Clin Pharmacol Ther. 2004;75(1):13-339 P Glycoprotein is Widely Distributed Efflux activity reduces intestinal absorption while enhancing elimination through liver and kidney At barrier sites (blood- brain, testes, or placenta), P-gp limits tissue exposure to potentially toxic compounds

10. Portal Vein P glycoprotein transports substrates back into the gut lumen

11. J Clin Invest. 1999; 104(2): 147–15311 P-Glycoprotein is Inducible Mean (n = 8) plasma concentration (mean ± SD) time curves of orally administered digoxin (1 mg) before (open circles) and during (filled circles) coadministration of rifampin (600 mg)

12. J Clin Invest. 1999; 104(2): 147–15312 Before Rifampin… Duodenal biopsy (villus tip, ×40) immunostained for P- glycoprotein before administration of rifampin

13. J Clin Invest. 1999; 104(2): 147–15313 9 Days Later… Duodenal biopsy (villus tip, ×40) immunostained for P- glycoprotein after administration of 600 mg of rifampin for 9 days

14. P-glycoprotein polymorphism Significant correlation between a polymorphism in exon 26 of MDR1, 3435C-T, with expression levels of MDR1 (Hoffmeyer et al., 2000) People who are homozygous for the 3435T allele have on average substantially lower intestinal P-gp expression than those homozygous for the C allele 83% of west africans (Ghanaians) studied and 61% of African Americans were homozygous for the C allele, whereas only 26% Caucasians and 34% Janpanese showed this genotype (P<0.0001)

15. No Clinically relevant polymorphisms were reported for CYP3A4

16. MDR1 Haplotypes CEPH population Yoruba population

17. MDR1 gene LD blocks CEPH population

18. Yoruba population

19. CYP3A4 Haplotypes CEPH population Yoruba population

20. CYP3A4 gene LD blocks CEPH population

21. Yoruba population

22. MDR1 gene tag SNP ratios in CEPH population rs6946119867735163'UTR CT=20 CC=4 TT=36TC=0 NN=0 rs7802783867750483'UTR CT=10 CC=45 TT=1TC=0 NN=4 rs1055302867775673'UTR AG=10 AA=1 GG=49GA=0 NN=0 rs697988586782112Int27 AG=24 AA=2 GG=32GA=0 NN=2 rs443757586783967Int26 AG=36 AA=12 GG=9GA=0 NN=3 rs100220486786148Int26 GT=29 GG=11 TT=13TG=0 NN=7 rs694944886786465Int26 CT=33 CC=19 TT=8TC=0 NN=0 rs4148743 rs2373589 rs778708286801702Int22 AG=20 AA=1 GG=39GA=0 NN=0 rs1023441186809543Int21 AT=31 AA=20 TT=7TA=0 NN=2 rs414873786815803Int18 AG=30 AA=19 GG=11GA=0 NN=0 rs1027660386816178Int18 CT=16 CC=1 TT=42TC=0 NN=1 rs209176686819155Int16 CT=30 CC=21 TT=9TC=0 NN=0 rs112850386824252Ex13 CT=31 CC=21 TT=8TC=0 NN=0 rs192224186830545Int9 AG=30 AA=3 GG=27GA=0 NN=0 rs1177298786830669Int9 CG=18 CC=41 GG=1GC=0 NN=0 rs1024426686833118Int9 GT=15 GG=2 TT=41TG=0 NN=2 rs86875586834581Int9 AC=33 AA=6 CC=21CA=0 NN=0 rs1323713286836320Int8 CG=28 CC=28 GG=4GC=0 NN=0 rs120217086839757Int8 AG=32 AA=13 GG=15GA=0 NN=0 rs223501586844215Int5 GT=22 GG=32 TT=0TG=0 NN=6 rs695097886845118Int5 AT=29 AA=27 TT=3TA=0 NN=1 rs252046486845737Int5 AG=31 AA=7 GG=22GA=0 NN=0 rs1233418386846031Int5 CT=26 CC=2 TT=32TC=0 NN=0 rs1026086286846133Int5 CG=24 CC=2 GG=33GC=0 NN=1 rs1026499086847266Int5 CT=32 CC=6 TT=22TC=0 NN=0 rs1322672686851266Int5 CT=12 CC=44 TT=0TC=0 NN=4 rs120217286855625Int5 GT=28 GG=13 TT=19TG=0 NN=0 rs120217186855696Int5 AT=26 AA=13 TT=20TA=0 NN=1 rs414873386857883Int5 CT=12 CC=0 TT=48TC=0 NN=0 rs121115286859765Int4 GT=14 GG=46 TT=0TG=0 NN=0 rs1732762486861468Int4 GT=14 GG=45 TT=1TG=0 NN=0 rs1176387286861866Int4 CT=35 CC=8 TT=8TC=0 NN=9 rs780277386862998Int4 AG=42 AA=12 GG=6GA=0 NN=0 rs1322914386864132Int4 CG=38 CC=9 GG=13GC=0 NN=0 rs1253551286864985Int4 CT=36 CC=4 TT=20TC=0 NN=0 rs218852686865213Int4 AG=40 AA=5 GG=15GA=0 NN=0 rs378924386865537Int4 CT=40 CC=6 TT=14TC=0 NN=0 rs221410286874152Ex3 AG=16 AA=0 GG=44GA=0 NN=0 rs1323330886889611Int1 CT=36 CC=16 TT=8TC=0 NN=0 rs1024687886920292Int1 AG=29 AA=3 GG=28GA=0 NN=0 rs2157930