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Avoidance of pseudogene interference in the detection of 3′ deletions in PMS2
Author(s) -
Vaughn Cecily P.,
Hart Kimberly J.,
Samowitz Wade S.,
Swensen Jeffrey J.
Publication year - 2011
Publication title -
human mutation
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.981
H-Index - 162
eISSN - 1098-1004
pISSN - 1059-7794
DOI - 10.1002/humu.21540
Subject(s) - pseudogene , biology , pms2 , genetics , multiplex ligation dependent probe amplification , msh2 , msh6 , gene , exon , lynch syndrome , mutation , computational biology , dna mismatch repair , germline mutation , genome , dna repair
Lynch syndrome is characterized by mutations in the mismatch repair genes MLH1 , MSH2 , MSH6 , and PMS2 . In PMS2 , detection of mutations is confounded by numerous pseudogenes. Detection of 3′ deletions is particularly complicated by the pseudogene PMS2CL , which has strong similarity to PMS2 exons 9 and 11–15, due to extensive gene conversion. A newly designed multiplex ligation‐dependent probe amplification (MLPA) kit incorporates probes for variants found in both PMS2 and PMS2CL . This provides detection of deletions, but does not allow localization of deletions to the gene or pseudogene. To address this, we have developed a methodology incorporating reference samples with known copy numbers of variants, and paired MLPA results with sequencing of PMS2 and PMS2CL . We tested a subset of clinically indicated samples for which mutations were either unidentified or not fully characterized using existing methods. We identified eight unrelated patients with deletions encompassing exons 9–15, 11–15, 13–15, 14–15, and 15. By incorporating specific, characterized reference samples and sequencing the gene and pseudogene it is possible to identify deletions in this region of PMS2 and provide clinically relevant results. This methodology represents a significant advance in the diagnosis of patients with Lynch syndrome caused by PMS2 mutations. Hum Mutat 32:1063–1071, 2011. © 2011 Wiley‐Liss, Inc.