| Phenotype | Affected / denominator | Median age at diagnosis, years (range) | Tentative HPO label suggestion |
|---|---:|---:|---|
| Colorectal cancer | 39/77 (50.6%) | 50 (31–73) | Colorectal carcinoma |
| Breast cancer | 25/77 (32.5%); 24/40 women (60.0%) | 47 (36–68) | Breast carcinoma |
| Endometrial/uterine cancer | 8/77 (10.4%); 8/40 women (20.0%) | 57 (45–74) | Endometrial carcinoma |
| Meningioma | 14/77 (18.2%); 13/40 women (32.5%) | 47 (37–69) | Meningioma |
| Colorectal polyposis (≥10 polyps) | 39/70 with reported colonoscopy (55.7%) | Not reported | Colorectal polyposis; Adenomatous polyposis |
| Basal-cell carcinoma | 9/77 (11.7%) | Not reported | Basal cell carcinoma |
| Urothelial/bladder cancer | 6/77 (7.8%) | Not reported separately | Bladder carcinoma; Urothelial carcinoma |
| **Interpretation disclaimer** | **These are observed proportions in a literature-derived, clinically ascertained series of 77 biallelic carriers—not prospective lifetime penetrance estimates. Denominators vary with sex and available evaluations.** | — | — |
| **Evidence** | **Gao et al., 2025 systematic review and Table 2** (pqac-00000028, pqac-00000037, pqac-00000038, pqac-00000041, pqac-00000042) | — | — |


*Table: Clinical phenotype frequencies and ages reported in the 2025 systematic review of 77 individuals with biallelic NTHL1 pathogenic variants. These ascertainment-sensitive proportions should not be interpreted as lifetime penetrance.*