Table 1. Characteristics of 356 White Colorectal Cancer Families with No Evidence of Defective Mismatch Repair, N (%).
| Ascertainment Method | ||||
| Population-basedN = 189 | Clinic-basedN = 88 | UnknownaN = 79 | ||
| Mean Age of Diagnosis | <50 years | 24 (13%) | 19 (22%) | 15 (19%) |
| ≥50 years | 165 (87%) | 69 (78%) | 64 (81%) | |
| Number of Affected Individuals | 2 | 115 (61%) | 26 (30%) | 59 (75%) |
| 3 | 51 (27%) | 27 (31%) | 11 (14%) | |
| 4–10 | 23 (12%) | 35 (40%) | 9 (11%) | |
| MSIb | MSS | 119 (63%) | 61 (69%) | 29 (37%) |
| MSI-L | 9 (5%) | 6 (7%) | 0 | |
| Unknownd | 61 (32%) | 21 (24%) | 50 (63%) | |
| IHC Expression of MMR Genesc | No Loss | 147 (78%) | 77 (88%) | 31 (39%) |
| Unknownd | 42 (22%) | 11 (13%) | 48 (61%) | |
a
Ascertainment method not reported.
b
Microsatellite stability of the tumor; MSS indicates that the tumor was microsatellite stable; MSI-L indicates that the tumor had low microsatellite instability; Unknown indicates that the tumor stability status was not available.
c
Mismatch repair status of the tumor by immunohistochemical analysis; No loss indicates that the tumor showed complete presence of protein expression of all the MMR genes tested (MLH1, MSH2, MSH6, and PMS2); Unknown indicates that the tumor MMR-expression status was not available.
d
Unknown for both MSI and IHC on 67 families is due to not being tested but had a LOD<0.04 within 20 kb surrounding MSH2, MLH1, MSH6, PMS2, PMS1, MSH3, or MLH3.