| 1. |
- Clendenning, M, et al.
(författare)
-
A frame-shift mutation of PMS2 is a widespread cause of Lynch syndrome
- 2008
-
Ingår i: Journal of Medical Genetics. - : BMJ. - 0022-2593 .- 1468-6244. ; 45:6, s. 340-345
-
Tidskriftsartikel (refereegranskat)abstract
- Background: When compared to the other mismatch repair genes involved in Lynch syndrome, the identification of mutations within PMS2 has been limited (<2% of all identified mutations), yet the immunohistochemical analysis of tumour samples indicates that approximately 5% of Lynch syndrome cases are caused by PMS2. This disparity is primarily due to complications in the study of this gene caused by interference from pseudogene sequences. Methods: Using a recently developed method for detecting PMS2 specific mutations, we have screened 99 patients who are likely candidates for PMS2 mutations based on immunohistochemical analysis. Results: We have identified a frequently occurring frame-shift mutation (c.736_741del 6ins11) in 12 ostensibly unrelated Lynch syndrome patients (20% of patients we have identified with a deleterious mutation in PMS2, n = 61). These individuals all display the rare allele (population frequency <0.05) at a single nucleotide polymorphism (SNP) in exon 11, and have been shown to possess a short common haplotype, allowing us to calculate that the mutation arose around 1625 years ago (65 generations; 95% confidence interval 22 to 120). Conclusion: Ancestral analysis indicates that this mutation is enriched in individuals with British and Swedish ancestry. We estimate that there are >10 000 carriers of this mutation in the USA alone. The identification of both the mutation and the common haplotype in one Swedish control sample (n = 225), along with evidence that Lynch syndrome associated cancers are rarer than expected in the probands' families, would suggest that this is a prevalent mutation with reduced penetrance.
|
|
| 2. |
- Clendenning, M, et al.
(författare)
-
Long-range PCR facilitates the identification of PMS2-specific mutations
- 2006
-
Ingår i: Human Mutation. - : Hindawi Limited. - 1059-7794 .- 1098-1004. ; 27:5, s. 490-495
-
Tidskriftsartikel (refereegranskat)abstract
- Mutations within the DNA mismatch repair gene, "postmeiotic segregation increased 2" (PMS2), have been associated with a predisposition to hereditary nonpolyposis colorectal cancer (HNPCC; Lynch syndrome). The presence of a large family of highly homologous PMS2 pseudogenes has made previous attempts to sequence PMS2 very difficult. Here, we describe a novel method that utilizes long-range PCR as a way to preferentially amplify PMS2 and not the pseudogenes. A second, exon-specific, amplification from diluted long-range products enables us to obtain a clean sequence that shows no evidence of pseudogene contamination. This method has been used to screen a cohort of patients whose tumors were negative for the PMS2 protein by immunohistochemistry and had not shown any mutations within the MLH1 gene. Sequencing of the PMS2 gene from 30 colorectal and I I endometrial cancer patients identified 10 novel sequence changes as well as 17 sequence changes that had previously been identified. In total, putative pathologic mutations were detected in 11 of the 41 families. Among these were five novel mutations, c.705+1G > T, c.736-741del6ins11, c.862_863del, c.1688G > T, and c.2007-IG > A. We conclude that PMS2 mutation detection in selected Lynch syndrome and Lynch syndrome-like patients is both feasible and desirable.
|
|
| 3. |
|
|
| 4. |
|
|
