Quantification of sequence exchange events between PMS2 and PMS2CL provides a basis for improved mutation scanning of Lynch syndrome patients.
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, co-amplifying 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.
van der Klift
Heleen M
HM
Department of Human Genetics, Leiden University Medical Centre, Albinusdreef 2, Leiden, The Netherlands. hvdklift@lumc.nl
Tops
Carli M J
CM
Bik
Elsa C
EC
Boogaard
Merel W
MW
Borgstein
Anne-Marijke
AM
Hansson
Kerstin B M
KB
Ausems
Margreet G E M
MG
Gomez Garcia
Encarna
E
Green
Andrew
A
Hes
Frederik J
FJ
Izatt
Louise
L
van Hest
Liselotte P
LP
Alonso
Angel M
AM
Vriends
Annette H J T
AH
Wagner
Anja
A
van Zelst-Stams
Wendy A G
WA
Vasen
Hans F A
HF
Morreau
Hans
H
Devilee
Peter
P
Wijnen
Juul T
JT
D000251:Adenosine Triphosphatases / Q000235:genetics*; D016022:Case-Control Studies; D003123:Colorectal Neoplasms, Hereditary Nonpolyposis / Q000235:genetics*; D045643:DNA Repair Enzymes / Q000235:genetics*; D004268:DNA-Binding Proteins / Q000235:genetics*; D006801:Humans; D000070976:Mismatch Repair Endonuclease PMS2; D009154:Mutation; D016133:Polymerase Chain Reaction / Q000379:methods*; D011544:Pseudogenes / Q000235:genetics
D004268:DNA-Binding Proteins; D000251:Adenosine Triphosphatases; C094934:PMS2 protein, human; D000070976:Mismatch Repair Endonuclease PMS2; D045643:DNA Repair Enzymes