Yield of Lynch Syndrome Surveillance for Patients With Pathogenic Variants in DNA Mismatch Repair Genes.

BACKGROUND & AIMS: Patients with Lynch syndrome are offered the same colorectal cancer (CRC) surveillance programs (colonoscopy every 2 years), regardless of the pathogenic DNA mismatch repair gene variant the patient carries. We aimed to assess the yield of surveillance for patients with these variants in MLH1, MSH2, MSH6, and PMS2. METHODS: We analyzed data on colonoscopy surveillance, including histopathology analysis, from all patients diagnosed with Lynch syndrome (n = 264) at a single center. We compared the development of (advanced) adenomas and CRC among patients with pathogenic variants in the DNA mismatch repair genes MLH1 (n = 55), MSH2 (n = 44), MSH6 (n = 143), or PMS2 (n = 22) over 1836 years of follow-up (median follow-up of 6 years per patient). RESULTS: At first colonoscopy, CRC was found in 8 patients. During 916 follow-up colonoscopies, CRC was found in 9 patients. No CRC was found in patients with variants in MSH6 or PMS2 over the entire follow-up period. There were no significant differences in the number of colonoscopies with adenomas or advanced adenomas among the groups. The median time of adenoma development was 3 years (IQR, 2-6 years). There were no significant differences in time to development of adenoma. However, patients with variants in MSH6 had a significant longer time to development of advanced neoplasia (advanced adenoma or CRC) than patients in the other groups. Six carriers died during follow up (5 from cancer, of which 3 from pancreatic cancer). CONCLUSIONS: No CRC was found during follow-up of patients with Lynch syndrome carrying pathogenic variants in MSH6; advanced neoplasia developed over shorter follow-up time periods in patients with pathogenic variants in MLH1 or MSH2. The colonoscopy interval for patients with pathogenic variants in MSH6 might be increased to 3 years from the regular 2-year interval.

Suspected Lynch syndrome associated MSH6 variants: A functional assay to determine their pathogenicity.

Lynch syndrome (LS) is a hereditary cancer predisposition caused by inactivating mutations in DNA mismatch repair (MMR) genes. Mutations in the MSH6 DNA MMR gene account for approximately 18% of LS cases. Many LS-associated sequence variants are nonsense and frameshift mutations that clearly abrogate MMR activity. However, missense mutations whose functional implications are unclear are also frequently seen in suspected-LS patients. To conclusively diagnose LS and enroll patients in appropriate surveillance programs to reduce morbidity as well as mortality, the functional consequences of these variants of uncertain clinical significance (VUS) must be defined. We present an oligonucleotide-directed mutagenesis screen for the identification of pathogenic MSH6 VUS. In the screen, the MSH6 variant of interest is introduced into mouse embryonic stem cells by site-directed mutagenesis. Subsequent selection for MMR-deficient cells using the DNA damaging agent 6-thioguanine (6TG) allows the identification of MMR abrogating VUS because solely MMR-deficient cells survive 6TG exposure. We demonstrate the efficacy of the genetic screen, investigate the phenotype of 26 MSH6 VUS and compare our screening results to clinical data from suspected-LS patients carrying these variant alleles.

Routine Molecular Analysis for Lynch Syndrome Among Adenomas or Colorectal Cancer Within a National Screening Program.

BACKGROUND & AIMS: It is important to identify individuals with Lynch syndrome because surveillance programs can reduce their morbidity and mortality from colorectal cancer (CRC). We assessed the diagnostic yield of immunohistochemistry to detect Lynch syndrome in patients with advanced and multiple adenomas within our national CRC screening program. METHODS: We performed a prospective study of all participants (n = 1101; 55% male; median age, 66 years; interquartile range, 61-70 years) referred to the Erasmus MC in The Netherlands after a positive result from a fecal immunohistochemical test, from December 2013 to December 2016. Colon tissues were collected from patients with advanced adenomas, ≥4 nonadvanced adenomas, or CRC, and analyzed by immunohistochemistry to identify patients with loss of mismatch repair (MMR) proteins (MLH1, MSH2, MSH6, or PMS2): a marker of Lynch syndrome. Specimens from patients with loss of MLH1 were analyzed for MLH1 promoter hypermethylation. Patients with an MMR-deficient tumor or adenoma without MLH1 promoter hypermethylation were referred for genetic analysis. RESULTS: At colonoscopy, 456 patients (41%) (65% male; mean age, 67 years; interquartile range, 63-71 years) were found to have CRC and/or an adenoma eligible for analysis by immunohistochemistry. Of 56 CRCs, 7 (13%) had lost an MMR protein and 5 had hypermethylation of the MLH1 promoter. Analyses of tumor DNA revealed that 2 patients without MLH1 promoter hypermethylation had developed sporadic tumors. In total, 400 patients with adenomas were analyzed. Of the examined adenomas, 208 (52%) had a villous component and/or high-grade dysplasia: 186 (47%) had a villous component and 41 (10%) had high-grade dysplasia. Only 1 adenoma had lost an MMR protein. This adenoma was found to have 2 somatic mutations in MSH6. CONCLUSIONS: In a CRC screening program in The Netherlands for individuals aged 55 to 75 years, routine screening for Lynch syndrome by immunohistochemistry analysis of colon tissues from patients with advanced and multiple adenomas identified no individuals with this genetic disorder.

Small-bowel Surveillance in Patients With Peutz-Jeghers Syndrome: Comparing Magnetic Resonance Enteroclysis and Double Balloon Enteroscopy.

BACKGROUND AND STUDY AIMS: Small-bowel surveillance with polypectomy of polyps ≥15 mm prevents complications in patients with Peutz-Jeghers syndrome (PJS). We aimed to compare magnetic resonance enteroclysis (MRE) and double balloon enteroscopy (DBE) for diagnostic yield of these polyps and for patient preference. MATERIALS AND METHODS: PJS patients prospectively underwent MRE followed by proximal DBE within 20 weeks. Endoscopists were blinded to the MRE results. We compared number of polyps ≥15 mm detected by MRE and DBE. Patients' perceptions of both procedures were assessed using questionnaires. RESULTS: Fifteen PJS patients (67% males, median age 47 y) underwent both MRE and DBE. Polyps ≥15 mm were identified by MRE and/or DBE in 12/15 (80%) patients. There was no significant difference in the detection of polyps ≥15 mm (38 by MRE vs. 50 by DBE, P=0.37). Sensitivity for these polyps was 62% (38/61) for MRE and 82% (50/61) for DBE. Patients' perceived shame and burden did not differ significantly between MRE and DBE. Patients reported significantly more pain during preparation for MRE than for DBE (moderate vs. no pain, P=0.02), although perceived pain during the procedures was comparable (both mild, P=0.89). For future small-bowel surveillance 10/13 (77%) patients preferred DBE over MRE (P=0.09). CONCLUSIONS: Our results suggest that MRE and DBE have a comparable diagnostic yield of polyps ≥15 mm. However, DBE allows for direct intervention and was preferred over MRE by most patients in this series. Larger cohorts of PJS patients are needed to fully evaluate the diagnostic yield of DBE compared with other modalities.

Cost-effectiveness of routine screening for Lynch syndrome in colorectal cancer patients up to 70 years of age.

PURPOSE: To assess the cost-effectiveness of routine Lynch syndrome (LS) screening among colorectal cancer (CRC) patients ≤70 years of age. METHODS: A population-based series of CRC patients ≤70 years of age was routinely screened for LS. We calculated life years gained (LYG) and incremental cost-effectiveness ratios (ICERs) for different age cutoffs and comparing age-targeted screening with the revised Bethesda guidelines. RESULTS: Screening 1,117 CRC patients identified 23 LS patients, of whom 7 were ≤50 years of age, 7 were 51-60, and 9 were 61-70. Additionally, 70 LS carriers were identified among relatives (14, 42, and 14 per age category). Screening amounted to 205.9 LYG or 43.6, 118.0, and 44.3 LYG per age category. ICERs were [euro ]4.226/LYG for screening CRC patients ≤60 years of age compared with those ≤50 years and [euro ]7.051/LYG for screening CRC patients ≤70 years compared with those ≤60 years. The revised Bethesda guidelines identified 70 of 93 (75%) LS carriers. The ICER for LS screening in CRC patients ≤70 years of age compared with the revised Bethesda guidelines was [euro ]7.341/LYG. All ICERs remained less than [euro ]13.000/LYG in one-way sensitivity analyses. CONCLUSION: Routine LS screening by analysis of microsatellite instability, immunohistochemistry, and MLH1 hypermethylation in CRC patients ≤70 years of age is a cost-effective strategy with important clinical benefits for CRC patients and their relatives.Genet Med 18 10, 966-973.

Cost-effectiveness of routine screening for Lynch syndrome in endometrial cancer patients up to 70years of age.

PURPOSE: To assess cost-effectiveness of routine screening for Lynch Syndrome (LS) in endometrial cancer (EC) patients ≤70years of age. METHODS: Consecutive EC patients ≤70years of age were screened for LS by analysis of microsatellite instability, immunohistochemistry and MLH1 hypermethylation. Costs and health benefit in life years gained (LYG) included surveillance for LS carriers among EC patients and relatives. We calculated incremental cost-effectiveness ratios (ICERs) comparing LS screening among EC patients ≤70years with ≤50years and the revised Bethesda guidelines. RESULTS: Screening for LS in 179 EC patients identified 7 LS carriers; 1 was ≤50 and 6 were 51-70years. Per age category 18 and 9 relatives were identified as LS carrier. Screening resulted in 74,7 LYG (45,4 and 29,3 LYG per age category). The ICER for LS screening in EC patients ≤70 compared with ≤50years was €5,252/LYG. The revised Bethesda guidelines missed 4/7 (57%) LS carriers among EC patients. The ICER for LS screening in EC patients ≤70years of age compared with the revised Bethesda guidelines was €6,668/LYG. Both ICERs remained <€16,000/LYG in sensitivity analyses. CONCLUSION: Routine LS screening in EC patients ≤70years is a cost-effective strategy, allowing colorectal cancer prevention in EC patients and their relatives.

Somatic aberrations of mismatch repair genes as a cause of microsatellite-unstable cancers.

Lynch syndrome (LS) is caused by germline mutations in mismatch repair (MMR) genes, resulting in microsatellite-unstable tumours. Approximately 35% of suspected LS (sLS) patients test negative for germline MMR gene mutations, hampering conclusive LS diagnosis. The aim of this study was to investigate somatic MMR gene aberrations in microsatellite-unstable colorectal and endometrial cancers of sLS patients negative for germline MMR gene mutations. Suspected LS cases were selected from a retrospective Clinical Genetics Department diagnostic cohort and from a prospective multicentre population-based study on LS in The Netherlands. In total, microsatellite-unstable tumours of 40 sLS patients (male/female 20/20, median age 57 years) were screened for somatic MMR gene mutations by next-generation sequencing. In addition, loss of heterozygosity (LOH) of the affected MMR genes in these tumours as well as in 68 LS-associated tumours and 27 microsatellite-unstable tumours with MLH1 promoter hypermethylation was studied. Of the sLS cases, 5/40 (13%) tumours had two pathogenic somatic mutations and 16/40 (40%) tumours had a (likely) pathogenic mutation and LOH. Overall, LOH of the affected MMR gene locus was observed in 24/39 (62%) tumours with informative LOH markers. Of the LS cases and the tumours with MLH1 promoter hypermethylation, 39/61 (64%) and 2/21 (10%) tumours, respectively, demonstrated LOH. Half of microsatellite-unstable tumours of sLS patients without germline MMR gene mutations had two (likely) deleterious somatic MMR gene aberrations, indicating their sporadic origin. Therefore, we advocate adding somatic mutation and LOH analysis of the MMR genes to the molecular diagnostic workflow of LS.

Developmental and epileptic encephalopathy 56 due to YWHAG variants: 12 new cases and review of the literature.

BACKGROUND AND OBJECTIVES: Developmental and epileptic encephalopathy 56 (DEE-56) is caused by pathogenic variants in YWHAG and is characterized by early-onset epilepsy and neurodevelopmental delay. This study reports on a cohort of DEE-56 individuals, correlating antiseizure medication usage and comorbidities, to aid in understanding disease evolution. METHODS: We analyzed data from thirty-nine individuals aged 3-40 years with YWHAG variants, including 12 previously unreported individuals (2 of these with recurrent distal 7q11.23 deletions) and 27 previously published cases (21 families, including 3 adult individuals reported in a family case). Our assessments encompassed clinical, radiological, and genetic evaluations. All procedures adhered to standardized protocols for patient approvals, registrations, and data collection. RESULTS: Individuals with YWHAG variants exhibited variable psychomotor delay, with the majority experiencing mild intellectual disability. Early-onset seizures, particularly febrile seizures, were common, with various seizure types reported. Valproic acid has emerged as an effective antiseizure medication. Movement disorders were present in a subset of individuals, primarily manifesting as ataxia and tremor. Comorbidities such as autism spectrum disorders and attention deficit-hyperreactivity disorder were observed in a proportion of individuals. We identified a novel YWHAG variant (c.634_645del/p.Asn212_Ser215del) and expanded the genotypic spectrum of the disease. CONCLUSIONS: We provide insights into the clinical, radiological, and genetic features of YWHAG-related epileptic encephalopathy. Despite mild clinical symptoms, affected individuals face challenges in daily functioning, underscoring the need for comprehensive care. Valproic acid has been used for seizure control with variable results.

Genetic diagnostic yield in an 11-year cohort of craniosynostosis patients.

Craniosynostosis may present in isolation, 'non-syndromic', or with additional congenital anomalies/neurodevelopmental disorders, 'syndromic'. Clinical focus shifted from confirming classical syndromic cases to offering genetic testing to all craniosynostosis patients. This retrospective study assesses diagnostic yield of molecular testing by investigating prevalences of chromosomal and monogenic (likely) pathogenic variants in an 11-year cohort of 1020 craniosynostosis patients. 502 children underwent genetic testing. Pathogenic variants were identified in 174 patients (35%). Diagnostic yield was significantly higher in syndromic craniosynostosis (62%) than in non-syndromic craniosynostosis (6%). Before whole exome sequencing (WES) emerged, single-gene testing was performed using Sanger sequencing or multiplex ligation-dependent probe amplification (MLPA). Diagnostic yield was 11% and was highest for EFNB1, FGFR2, FGFR3, and IL11RA. Diagnostic yield for copy number variant analysis using microarray was 8%. From 2015 onwards, the WES craniosynostosis panel was implemented, with a yield of 10%. In unsolved, mainly syndromic, cases suspected of a genetic cause, additional WES panels (multiple congenital anomalies (MCA)/intellectual disability (ID)) or open exome analysis were performed with an 18% diagnostic yield. To conclude, microarray and the WES craniosynostosis panel are key to identifying pathogenic variants. in craniosynostosis patients. Given the advances in genetic diagnostics, we should look beyond the scope of the WES craniosynostosis panel and consider extensive genetic diagnostics (e.g. open exome sequencing, whole genome sequencing, RNA sequencing and episignature analysis) if no diagnosis is obtained through microarray and/or WES craniosynostosis panel. If parents are uncomfortable with more extensive diagnostics, MCA or ID panels may be considered.

Case Report and Review of the Literature: Congenital Diaphragmatic Hernia and Craniosynostosis, a Coincidence or Common Cause?

Congenital diaphragmatic hernia (CDH) is a life-threatening birth defect that presents as either an isolated diaphragm defect or as part of a complex disorder with a wide array of anomalies (complex CDH). Some patients with complex CDH display distinct craniofacial anomalies such as craniofrontonasal dysplasia or craniosynostosis, defined by the premature closure of cranial sutures. Using clinical whole exome sequencing (WES), we found a BCL11B missense variant in a patient with a left-sided congenital diaphragmatic hernia as well as sagittal suture craniosynostosis. We applied targeted sequencing of BCL11B in patients with craniosynostosis or with a combination of craniosynostosis and CDH. This resulted in three additional BCL11B missense mutations in patients with craniosynostosis. The phenotype of the patient with both CDH as well as craniosynostosis was similar to the phenotype of previously reported patients with BCL11B missense mutations. Although these findings imply that both craniosynostosis as well as CDH may be associated with BCL11B mutations, further studies are required to establish whether BCL11B variants are causative mutations for both conditions or if our finding was coincidental.

Gynecological Surveillance and Surgery Outcomes in Dutch Lynch Syndrome Carriers.

Lynch syndrome (LS) is caused by pathogenic germline variants in DNA mismatch repair (MMR) genes, predisposing female carriers for endometrial cancer (EC) and ovarian cancer (OC). Since gynecological LS surveillance guidelines are based on little evidence, we assessed its outcomes. Data regarding gynecological tumors, surveillance, and (risk-reducing) surgery were collected from female LS carriers diagnosed in our center since 1993. Of 505 female carriers, 104 had a gynecological malignancy prior to genetic LS diagnosis. Of 264 carriers eligible for gynecological management, 164 carriers gave informed consent and had available surveillance data: 38 MLH1, 25 MSH2, 82 MSH6, and 19 PMS2 carriers (median follow-up 5.6 years). Surveillance intervals were within advised time in >80%. Transvaginal ultrasound, endometrial sampling, and CA125 measurements were performed in 76.8%, 35.9%, and 40.6%, respectively. Four symptomatic ECs, one symptomatic OC, and one asymptomatic EC were diagnosed. Endometrial hyperplasia was found in eight carriers, of whom three were symptomatic. Risk-reducing surgery was performed in 73 (45.5%) carriers (median age 51 years), revealing two asymptomatic ECs. All ECs were diagnosed in FIGO I. Gynecological management in LS carriers varied largely, stressing the need for uniform, evidence-based guidelines. Most ECs presented early and symptomatically, questioning the surveillance benefit in its current form.

The Management of Peutz-Jeghers Syndrome: European Hereditary Tumour Group (EHTG) Guideline.

The scientific data to guide the management of Peutz-Jeghers syndrome (PJS) are sparse. The available evidence has been reviewed and discussed by diverse medical specialists in the field of PJS to update the previous guideline from 2010 and formulate a revised practical guideline for colleagues managing PJS patients. Methods: Literature searches were performed using MEDLINE, Embase, and Cochrane. Evidence levels and recommendation strengths were assessed using the Grading of Recommendations Assessment, Development and Evaluation (GRADE). A Delphi process was followed, with consensus being reached when ≥80% of the voting guideline committee members agreed. Recommendations and statements: The only recent guidelines available were for gastrointestinal and pancreatic management. These were reviewed and endorsed after confirming that no more recent relevant papers had been published. Literature searches were performed for additional questions and yielded a variable number of relevant papers depending on the subject addressed. Additional recommendations and statements were formulated. Conclusions: A decade on, the evidence base for recommendations remains poor, and collaborative studies are required to provide better data about this rare condition. Within these restrictions, multisystem, clinical management recommendations for PJS have been formulated.

Deficient histone H3 propionylation by BRPF1-KAT6 complexes in neurodevelopmental disorders and cancer.

Lysine acetyltransferase 6A (KAT6A) and its paralog KAT6B form stoichiometric complexes with bromodomain- and PHD finger-containing protein 1 (BRPF1) for acetylation of histone H3 at lysine 23 (H3K23). We report that these complexes also catalyze H3K23 propionylation in vitro and in vivo. Immunofluorescence microscopy and ATAC-See revealed the association of this modification with active chromatin. Brpf1 deletion obliterates the acylation in mouse embryos and fibroblasts. Moreover, we identify BRPF1 variants in 12 previously unidentified cases of syndromic intellectual disability and demonstrate that these cases and known BRPF1 variants impair H3K23 propionylation. Cardiac anomalies are present in a subset of the cases. H3K23 acylation is also impaired by cancer-derived somatic BRPF1 mutations. Valproate, vorinostat, propionate and butyrate promote H3K23 acylation. These results reveal the dual functionality of BRPF1-KAT6 complexes, shed light on mechanisms underlying related developmental disorders and various cancers, and suggest mutation-based therapy for medical conditions with deficient histone acylation.