MSH2 PMS2 MSH6 MLH1
It seems that patients with mutations on the MLH1 or MSH2-gene have other clinical features as opposed to patients with mutations on PMS2 of MSH6. Hematologic malignancies appear to occur more frequently in patients with MLH1 or MSH2 mutations than in patients with mutations of MSH6 or PMS2. In contrast, the latter group appears to have a higher prevalence of brain tumors. Furthermore, tumors tend to develop earlier in MLH1 or MSH2 mutation carriers than in patients with a mutation of MSH6 or PMS2.
| Genes | No. of patients (families) | Hematologic | Brain | LS*-associated | Others | Age at primary tumor | No. of patients with second malignancy |
| MLH1/MSH2 | 24 (14) | 11 | 8 | 7 | 3 | 4 | 5 |
| MSH6/PMS2 | 65 (39) | 19 | 36 | 44 | 4 | 9 | 26 |
*Lynch syndrome
Patients with biallelic mutations in MSH6 or PMS2 are more likely to survive their first tumors and develop a second malignancy. Overall, the prevalence of LS-associated tumors is higher in patients with biallelic MSH6 or PMS2 mutations than in biallelic MLH1 or MSH2 mutation-positive individuals.
A recent review of 146 reported cases of CMMRD revealed PMS2 mutations identified in 60% of cases, 20% in MLH1/MSH2 and 20% in MSH6 mutations.