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Medline ® Abstracts for References 77,78

of 'Lynch syndrome (hereditary nonpolyposis colorectal cancer): Clinical manifestations and diagnosis'

77
TI
Comprehensive Mutation Analysis of PMS2 in a Large Cohort of Probands Suspected of Lynch Syndrome or Constitutional Mismatch Repair Deficiency Syndrome.
AU
van der Klift HM, Mensenkamp AR, Drost M, Bik EC, Vos YJ, Gille HJ, Redeker BE, Tiersma Y, Zonneveld JB, García EG, Letteboer TG, Olderode-Berends MJ, van Hest LP, van Os TA, Verhoef S, Wagner A, van Asperen CJ, Ten Broeke SW, Hes FJ, de Wind N, Nielsen M, Devilee P, Ligtenberg MJ, Wijnen JT, Tops CM
SO
Hum Mutat. 2016;37(11):1162. Epub 2016 Aug 21.
 
Monoallelic PMS2 germline mutations cause 5%-15% of Lynch syndrome, a midlife cancer predisposition, whereas biallelic PMS2 mutations cause approximately 60% of constitutional mismatch repair deficiency (CMMRD), a rare childhood cancer syndrome. Recently improved DNA- and RNA-based strategies are applied to overcome problematic PMS2 mutation analysis due to the presence of pseudogenes and frequent gene conversion events. Here, we determined PMS2 mutation detection yield and mutation spectrum in a nationwide cohort of 396 probands. Furthermore, we studied concordance between tumor IHC/MSI (immunohistochemistry/microsatellite instability) profile and mutation carrier state. Overall, we found 52 different pathogenic PMS2 variants explaining 121 Lynch syndrome and nine CMMRD patients. In vitro mismatch repair assays suggested pathogenicity for three missense variants. Ninety-one PMS2 mutation carriers (70%) showed isolated loss of PMS2 in their tumors, for 31 (24%) no or inconclusive IHC was available, and eight carriers (6%) showed discordant IHC (presence of PMS2 or loss of both MLH1 and PMS2). Ten cases with isolated PMS2 loss (10%; 10/97) harbored MLH1 mutations. We confirmed that recently improved mutation analysis provides a high yield of PMS2 mutations in patients with isolated loss of PMS2 expression. Application of universal tumor prescreening methods will however miss some PMS2 germline mutation carriers.
AD
Department of Clinical Genetics, Leiden University Medical Centre, Leiden, The Netherlands. hvdklift@lumc.nl.
PMID
78
TI
Guidelines for surveillance of individuals with constitutional mismatch repair-deficiency proposed by the European Consortium "Care for CMMR-D" (C4CMMR-D).
AU
Vasen HF, Ghorbanoghli Z, Bourdeaut F, Cabaret O, Caron O, Duval A, Entz-Werle N, Goldberg Y, Ilencikova D, Kratz CP, Lavoine N, Loeffen J, Menko FH, Muleris M, Sebille G, Colas C, Burkhardt B, Brugieres L, Wimmer K, EU-Consortium Care for CMMR-D (C4CMMR-D)
SO
J Med Genet. 2014;51(5):283. Epub 2014 Feb 20.
 
Lynch syndrome (LS) is an autosomal dominant disorder caused by a defect in one of the DNA mismatch repair genes: MLH1, MSH2, MSH6 and PMS2. In the last 15 years, an increasing number of patients have been described with biallelic mismatch repair gene mutations causing a syndrome referred to as 'constitutional mismatch repair-deficiency' (CMMR-D). The spectrum of cancers observed in this syndrome differs from that found in LS, as about half develop brain tumours, around half develop digestive tract cancers and a third develop haematological malignancies. Brain tumours and haematological malignancies are mainly diagnosed in the first decade of life, and colorectal cancer (CRC) and small bowel cancer in the second and third decades of life. Surveillance for CRC in patients with LS is very effective. Therefore, an important question is whether surveillance for the most common CMMR-D-associated cancers will also be effective. Recently, a new European consortium was established with the aim of improving care for patients with CMMR-D. At a workshop of this group held in Paris in June 2013, one of the issues addressed was the development of surveillance guidelines. In 1968, criteria were proposed by WHO that should be met prior to the implementation of screening programmes. These criteria were used to assess surveillance in CMMR-D. The evaluation showed that surveillance for CRC is the only part of the programme that largely complies with the WHO criteria. The values of all other suggested screening protocols are unknown. In particular, it is questionable whether surveillance for haematological malignancies improves the already favourable outcome for patients with these tumours. Based on the available knowledge and the discussions at the workshop, the European consortium proposed a surveillance protocol. Prospective collection of all results of the surveillance is needed to evaluate the effectiveness of the programme.
AD
Department of Gastroenterology&Hepatology, Leiden University Medical Centre, Leiden, The Netherlands.
PMID