Quantification of sequence exchange events between PMS2 and PMS2CL provides a basis for improved mutation scanning of lynch syndrome patients |
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| Authors: | Heleen M. van der Klift Carli M.J. Tops Elsa C. Bik Merel W. Boogaard Anne‐Marijke Borgstein Kerstin B.M. Hansson Margreet G.E.M. Ausems Encarna Gomez Garcia Andrew Green Frederik J. Hes Louise Izatt Liselotte P. van Hest Angel M. Alonso Annette H.J.T. Vriends Anja Wagner Wendy A.G. van Zelst‐Stams Hans F.A. Vasen Hans Morreau Peter Devilee Juul T. Wijnen |
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| Affiliation: | 1. Department of Human Genetics, Leiden University Medical Centre, Leiden, The Netherlands;2. Department of Clinical Genetics, Leiden University Medical Centre, Leiden, The Netherlands;3. Department of Medical Genetics, University Medical Centre Utrecht, Utrecht, The Netherlands;4. Departments of Clinical Genetics, and Research Institute Growth & Development (GROW), University of Maastricht, The Netherlands;5. National Centre for Medical Genetics, Our Lady's Hospital, Dublin, Ireland;6. University College Dublin School of Medicine and Medical Science, Dublin, Ireland;7. Clinical Genetics Department, Guy's and St Thomas' NHS Foundation Trust, London, United Kingdom;8. Department of Clinical Genetics, VU University Medical Center, Amsterdam, The Netherlands;9. Department of Medical Genetics, Hospital Virgen del Camino, Pamplona, Spain;10. Department of Clinical Genetics, Erasmus Medical Center, Rotterdam, The Netherlands;11. Department of Gastroenterology and Hepatology, Leiden University Medical Centre and the Netherlands Foundation for the Detection of Hereditary Tumours, Leiden, The Netherlands;12. Department of Pathology, Leiden University Medical Centre, Leiden, The Netherlands |
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| Abstract: | Heterozygous mutations in PMS2 are involved in Lynch syndrome, whereas biallelic mutations are found in Constitutional mismatch repair‐deficiency syndrome patients. Mutation detection is complicated by the occurrence of sequence exchange events between the duplicated regions of PMS2 and PMS2CL. We investigated the frequency of such events with a nonspecific polymerase chain reaction (PCR) strategy, coamplifying both PMS2 and PMS2CL sequences. This allowed us to score ratios between gene and pseudogene‐specific nucleotides at 29 PSV sites from exon 11 to the end of the gene. We found sequence transfer at all investigated PSVs from intron 12 to the 3′ end of the gene in 4 to 52% of DNA samples. Overall, sequence exchange between PMS2 and PMS2CL was observed in 69% (83/120) of individuals. We demonstrate that mutation scanning with PMS2‐specific PCR primers and MLPA probes, designed on PSVs, in the 3′ duplicated region is unreliable, and present an RNA‐based mutation detection strategy to improve reliability. Using this strategy, we found 19 different putative pathogenic PMS2 mutations. Four of these (21%) are lying in the region with frequent sequence transfer and are missed or called incorrectly as homozygous with several PSV‐based mutation detection methods. Hum Mutat 31:578–587, 2010. © 2010 Wiley‐Liss, Inc. |
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| Keywords: | PMS2 PMS2CL pseudogene Lynch syndrome HNPCC |
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