Table 1.
Interpretation by PCR based methods of TPMT activity
| Genotype | PCR | Risk of hematopoietic toxicity | |
| 238G/238G | *1/*1 | 238 GG | -7% |
| 460G/460G | 460 GG | ||
| 719A/719A | 719 AA | ||
| 238G/238G | *1/*3A | 238GG | -35% |
| 460A/460A | 460GA | ||
| 719A/719G | 719AG | ||
| 238G/238G | *1/*3B | 238GG | -35% |
| 460G/460A | 460GA | ||
| 719A/719A | 719AA | ||
| 238G/238G | *1/*3C | 238GG | -35% |
| 460G/460G | 460GG | ||
| 719A/719G | 719AG | ||
| 238G/238G | *3B/*3C | 238GG | -100% |
| 460G/460G | 460GG | ||
| 719A/719G | 719AG | ||
| 238G/238G | *3A/*3C | 238GG | -100% |
| 460A/460G | 460GA | ||
| 719G/719G | 719GG | ||
| 238G/238G | *3A/*3B | 238GG | -100% |
| 460A/460A | 460AA | ||
| 719G/719A | 719AG | ||
Patients with *1/3A and *3A/*3C genotype have the same PCR results, however the risk to develop hematopoietic toxicity for patients with 2 low activity alleles is almost 100% compared to 35% only for heterozygous patients.