Identification and management of Lynch syndrome in the Middle East and North African countries: outcome of a survey in 12 countries

Background Lynch syndrome (LS), the most common inherited form of colorectal cancer (CRC), is responsible for 3% of all cases of CRC. LS is caused by a mismatch repair gene defect and is characterized by a high risk for CRC, endometrial cancer and several other cancers. Identification of LS is of utmost importance because colonoscopic surveillance substantially improves a patient's prognosis. Recently, a network of physicians in Middle Eastern and North African (ME/NA) countries was established to improve the identification and management of LS families. The aim of the present survey was to evaluate current healthcare for families with LS in this region. Methods A questionnaire was developed that addressed the following issues: availability of clinical management guidelines for LS; attention paid to family history of cancer; availability of genetic services for identification and diagnosis of LS; and assessment of knowledge of LS surveillance. Members of the network and authors of recent papers on LS from ME/NA and neighbouring countries were invited to participate in the survey and complete the online questionnaire. Results A total of 55 individuals were invited and 19 respondents from twelve countries including Algeria, Azerbaijan, Cyprus, Egypt, Iran, Jordan, Kuwait, Lebanon, Morocco, Palestine, Tunisia, and Turkey completed the questionnaire. The results showed that family history of CRC is considered in less than half of the surveyed countries. Guidelines for the management of LS are available in three out of twelve countries. The identification and selection of families for genetic testing were based on clinical criteria (Amsterdam criteria II or Revised Bethesda criteria) in most countries, and only one country performed universal screening. In most of the surveyed countries genetic services were available in few hospitals or only in a research setting. However, surveillance of LS families was offered in the majority of countries and most frequently consisted of regular colonoscopy. Conclusion The identification and management of LS in ME/NA countries are suboptimal and as a result most LS families in the region remain undetected. Future efforts should focus on increasing awareness of LS amongst both the general population and doctors, and on the improvement of the infrastructure in these countries

Diagnosis of Constitutional Mismatch Repair-Deficiency Syndrome Based on Microsatellite Instability and Lymphocyte Tolerance to Methylating Agents

BACKGROUND & AIMS: Patients with bi-allelic germline mutations in mismatch repair (MMR) genes (MLH1, MSH2, MSH6, or PMS2) develop a rare but severe variant of Lynch syndrome called constitutional MMR deficiency (CMMRD). This syndrome is characterized by early-onset colorectal cancers, lymphomas or leukemias, and brain tumors. There is no satisfactory method for diagnosis of CMMRD because screens for mutations in MMR genes are noninformative for 30% of patients. MMR-deficient cancer cells are resistant to genotoxic agents and have microsatellite instability (MSI), due to accumulation of errors in repetitive DNA sequences. We investigated whether these features could be used to identify patients with CMMRD. METHODS: We examined MSI by PCR analysis and tolerance to methylating or thiopurine agents (functional characteristics of MMR-deficient tumor cells) in lymphoblastoid cells (LCs) from 3 patients with CMMRD and 5 individuals with MMR-proficient LCs (controls). Using these assays, we defined experimental parameters that allowed discrimination of a series of 14 patients with CMMRD from 52 controls (training set). We then used the same parameters to assess 23 patients with clinical but not genetic features of CMMRD. RESULTS: In the training set, we identified parameters, based on MSI and LC tolerance to methylation, that detected patients with CMMRD vs controls with 100% sensitivity and 100% specificity. Among 23 patients suspected of having CMMRD, 6 had MSI and LC tolerance to methylation (CMMRD highly probable), 15 had neither MSI nor LC tolerance to methylation (unlikely to have CMMRD), and 2 were considered doubtful for CMMRD based on having only 1 of the 2 features. CONCLUSION: The presence of MSI and tolerance to methylation in LCs identified patients with CMMRD with 100% sensitivity and specificity. These features could be used in diagnosis of patients