Table 3. Molecular laboratory tests results and family history of 18 patients with an MSI-positive tumour with unexplained etiology.
| No. | Meth | IHC | Tumour tested for MSI | Age | Other tumour(s) | AC | 2fam | Tumours of close relatives |
|---|---|---|---|---|---|---|---|---|
| 149a | − | MLH1/PMS2− | Colon ascendens | 43 | − | − | − | 3co45 MSS |
| 499 | − | MLH1/PMS2− | Colon ascendens | 58 | − | − | − | |
| 445 | − | MLH1/PMS2− | Colon transversum | 49 | − | − | + | |
| 498 | − | MLH1/PMS2− | Sigmoid | 58 | co49 | − | − | |
| 172 | − | MLH1/PMS2− | Colon ascendens | 51 | − | − | + | |
| 373a | − | PMS2− | Caecum | 36 | − | − | − | |
| 554 | − | PMS2− | Colon transversum | 55 | co55 | − | − | 1co56 MSS |
| 582 | − | MSH2/MSH6− | Sigmoid | 33 | − | + | + | 1co47 MSI,IHC:MSH2−,meth− |
| 396 | − | MSH2/MSH6− | Appendix | 34 | − | − | − | |
| 224 | − | MSH2/MSH6− | Ileocecum | 53 | co34,co50 | + | + | |
| 580 | − | MSH2/MSH6− | Endometrium | 45 | − | − | − | |
| 718 | − | MSH2/MSH6− | Rectum | 18 | − | − | + | 1co47 MSI,HC:MSH2−,meth− |
| 736 | − | MSH2/MSH6− | Rectum | 58 | co58 MSS | − | − | |
| 421b | − | MSH6− | Colon ascendens | 53 | − | − | − | 1en62 MSI/IHC NA |
| 135 | − | PMS2/MSH2/MSH6−c | Colon ascendens | 27 | − | − | − | |
| 243 | − | PMS2/MSH2/MSH6−c | Colon transversum | 30 | − | − | + | |
| 127 | − | None− | Rectum | 54 | − | − | − | |
| 375d | − | None− | Caecum | 36 | − | − | + |
Meth, methylation analysis of MLH1 promoter; IHC, immunohistochemical analysis of MLH1, PMS2, MSH2, and MSH6; Tumour tested for MSI, tumour origin or exact location of tumour in case of colon cancer of tumour tested for MSI; Age, age at diagnosis of tumour tested for MSI; Other tumour(s), metachronous or synchronous cancer associated with Lynch syndrome of index patient and age at diagnosis; AC, Amsterdam II criteria (Vasen et al, 1999). 2fam, 2 first degree relatives (including index) with Lynch syndrome associated cancer, one of them with an age at diagnose below 50 years (Rodriguez-Bigas et al, 1997); Tumours of close relatives, tumours of close relatives tested for MSI and/or IHC, meth; +, positive; −, negative; NA, not assessable; co, colon; MSI, MSI positive; MSS, MSI negative; 1, first degree relative; 2, second degree relative; 3 third degree relative. (e.g. 3co45 MSS, a third degree relative of index patient had a colon tumour diagnosed at the age of 45 years which was MSI negative).
Carrier of unclassified variant c.1852_1853delinsGC (p.Lys618Ala) in MLH1.
Carrier of unclassified variant c.2117T>C (p.Phe706Ser) in MSH6 (Kets et al, 2006).
IHC difficult to interpret.
Carrier of unclassified variant c.250A>G (p.Lys84Glu) in MLH1 and c.984C>T (silent) in MSH2.