Table 1.
Four haplotypes and nine genotypes of MDR1 derived from SNP 2677G > T (exon 21) and SNP 3435C > T (exon 26)
| Genotype 00 | Genotype 01 | Genotype 02 | Genotype 10 | Genotype 11 | Genotype 12 | Genotype 20 | Genotype 21 | Genotype 22 | ||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Pos 2677 | g | g | g | g | g | g | g | T | g | T | g | T | T | T | T | T | T | T |
| Pos 3435 | C | C | C | T | T | T | C | C | C | T | T | T | C | C | C | T | T | T |
| Haplotype | 11 | 11 | 11 | 12 | 12 | 12 | 11 | 21 | 11 | 22 | 12 | 22 | 21 | 21 | 21 | 22 | 22 | 22 |
| or | ||||||||||||||||||
| Pos 2677 | g | T | ||||||||||||||||
| Pos 3435 | T | C | ||||||||||||||||
| 12 | 21 | |||||||||||||||||
Positions refer to the MDR1 cDNA sequence with the first base of the ATG start codon set to 1. The rare 2677A variant was not considered in genotype and haplotype analysis. Genotype coding: 0 homozygous identical to reference sequence (2677G, 3534C), 1 heterozygous, 2 homozygous different from reference sequence. The first digit refers to position 2677, the second digit to position 3435. Haplotype coding: 1 identical to reference sequence (2677G, 3534C), 2 different from reference sequence. The first digit refers to position 2677, the second digit to position 3435. For genotype 11, a second haplotype pair (12/21) is possible, however haplotype pair 11/22 is much more likely based on haplotype frequencies.