Uptake of prenatal diagnostic testing for retinoblastoma compared to other hereditary cancer syndromes in the Netherlands

Since the 1980s the genetic cause of many hereditary tumor syndromes has been elucidated. As a consequence, carriers of a deleterious mutation in these genes may opt for prenatal diagnoses (PND). We studied the uptake of prenatal diagnosis for five hereditary cancer syndromes in the Netherlands. Uptake for retinoblastoma (Rb) was compared with uptake for Von Hippel–Lindau disease (VHL), Li–Fraumeni syndrome (LFS), familial adenomatous polyposis (FAP), and hereditary breast ovarian cancer (HBOC). A questionnaire was completed by all nine DNA-diagnostic laboratories assessing the number of independent mutation-positive families identified from the start of diagnostic testing until May 2013, and the number of PNDs performed for these syndromes within these families. Of 187 families with a known Rb-gene mutation, 22 had performed PND (11.8%), this was significantly higher than uptake for FAP (1.6%) and HBOC (<0.2%). For VHL (6.5%) and LFS (4.9%) the difference was not statistically significant. PND for Rb started 3 years after introduction of diagnostic DNA testing and remained stable over the years. For the other cancer syndromes PND started 10–15 years after the introduction and uptake for PND showed an increase after 2009. We conclude that uptake of PND for Rb was significantly higher than for FAP and HBOC, but not different from VHL and LFS. Early onset, high penetrance, lack of preventive surgery and perceived burden of disease may explain these differences

Evaluation of current prediction models for Lynch syndrome: updating the PREMM5 model to identify PMS2 mutation carriers

Analysis and support of clinical decision makin

APC mosaicism, not always isolated: two first-degree relatives with apparently distinct APC mosaicism

Cellular mechanisms in basic and clinical gastroenterology and hepatolog

Implementation of paediatric precision oncology into clinical practice: The Individualized Therapies for Children with cancer program ‘iTHER’

iTHER is a Dutch prospective national precision oncology program aiming to define tumour molecular profiles in children and adolescents with primary very high-risk, relapsed, or refractory paediatric tumours. Between April 2017 and April 2021, 302 samples from 253 patients were included. Comprehensive molecular profiling including low-coverage whole genome sequencing (lcWGS), whole exome sequencing (WES), RNA sequencing (RNA-seq), Affymetrix, and/or 850k methylation profiling was successfully performed for 226 samples with at least 20% tumour content. Germline pathogenic variants were identified in 16% of patients (35/219), of which 22 variants were judged causative for a cancer predisposition syndrome. At least one somatic alteration was detected in 204 (90.3%), and 185 (81.9%) were considered druggable, with clinical priority very high (6.1%), high (21.3%), moderate (26.0%), intermediate (36.1%), and borderline (10.5%) priority. iTHER led to revision or refinement of diagnosis in 8 patients (3.5%). Temporal heterogeneity was observed in paired samples of 15 patients, indicating the value of sequential analyses. Of 137 patients with follow-up beyond twelve months, 21 molecularly matched treatments were applied in 19 patients (13.9%), with clinical benefit in few. Most relevant barriers to not applying targeted therapies included poor performance status, as well as limited access to drugs within clinical trial. iTHER demonstrates the feasibility of comprehensive molecular profiling across all ages, tumour types and stages in paediatric cancers, informing of diagnostic, prognostic, and targetable alterations as well as reportable germline variants. Therefore, WES and RNA-seq is nowadays standard clinical care at the Princess Máxima Center for all children with cancer, including patients at primary diagnosis. Improved access to innovative treatments within biology-driven combination trials is required to ultimately improve survival

Implementation of paediatric precision oncology into clinical practice: The Individualized Therapies for Children with cancer program ‘iTHER’

iTHER is a Dutch prospective national precision oncology program aiming to define tumour molecular profiles in children and adolescents with primary very high-risk, relapsed, or refractory paediatric tumours. Between April 2017 and April 2021, 302 samples from 253 patients were included. Comprehensive molecular profiling including low-coverage whole genome sequencing (lcWGS), whole exome sequencing (WES), RNA sequencing (RNA-seq), Affymetrix, and/or 850k methylation profiling was successfully performed for 226 samples with at least 20% tumour content. Germline pathogenic variants were identified in 16% of patients (35/219), of which 22 variants were judged causative for a cancer predisposition syndrome. At least one somatic alteration was detected in 204 (90.3%), and 185 (81.9%) were considered druggable, with clinical priority very high (6.1%), high (21.3%), moderate (26.0%), intermediate (36.1%), and borderline (10.5%) priority. iTHER led to revision or refinement of diagnosis in 8 patients (3.5%). Temporal heterogeneity was observed in paired samples of 15 patients, indicating the value of sequential analyses. Of 137 patients with follow-up beyond twelve months, 21 molecularly matched treatments were applied in 19 patients (13.9%), with clinical benefit in few. Most relevant barriers to not applying targeted therapies included poor performance status, as well as limited access to drugs within clinical trial. iTHER demonstrates the feasibility of comprehensive molecular profiling across all ages, tumour types and stages in paediatric cancers, informing of diagnostic, prognostic, and targetable alterations as well as reportable germline variants. Therefore, WES and RNA-seq is nowadays standard clinical care at the Princess Máxima Center for all children with cancer, including patients at primary diagnosis. Improved access to innovative treatments within biology-driven combination trials is required to ultimately improve survival

Mutations in SDHD are the major determinants of the clinical characteristics of Dutch head and neck paraganglioma patients

OBJECTIVE Head and neck paragangliomas (HNPGL) are associated with mutations in genes encoding subunits of succinate dehydrogenase (SDH). The aim of this study was to evaluate SDH mutations, family history and phenotypes of patients with HNPGL in the Netherlands. DESIGN We evaluated the clinical data and the mutation status of 236 patients referred between 1950 and 2009 to Leiden University Medical Center. RESULTS The large majority of the patients carried mutations in SDHD (83%), and the p.Asp92Tyr Dutch founder mutation in SDHD alone accounted for 72% of all patients with HNPGL. A mutation in SDHAF2 was found in 4%, mutations in SDHB in 3% and a mutation in SDHC was identified in a single patient (0·4%). Over 80% of patients presented with positive family history, of whom 99·5% carried a mutation in an SDH gene. SDH mutations were also found in 56% of isolated patients, chiefly in SDHD (46%), but also in SDHB (8%) and SDHC (2%). The clinical parameters of these different subgroups are discussed: including the age at diagnosis, associated pheochromocytomas, tumour multifocality and malignancy rate. CONCLUSION The majority of Dutch patients with HNPGL present with a positive family history, in contrast to other European countries. The clinical characteristics of patients with HNPGL are chiefly determined by founder mutations in SDHD, the major causative gene in both familial and isolated patients with HNPGL. The high frequency of founder mutations in SDHD suggests a higher absolute prevalence of paraganglioma syndrome in the Netherlands.Hereditary cancer genetic

High prevalence of founder mutations of the succinate dehydrogenase genes in the Netherlands

Hensen EF, van Duinen N, Jansen JC, Corssmit EPM, Tops CMJ, Romijn JA, Vriends AHJT, van der Mey AGL, Cornelisse CJ, Devilee P, Bayley JP. High prevalence of founder mutations of the succinate dehydrogenase genes in the Netherlands. Mutations in four genes encoding subunits or cofactors of succinate dehydrogenase (SDH) cause hereditary paraganglioma and pheochromocytoma syndromes. Mutations in SDHB and SDHD are generally the most common, whereas mutations in SDHC and SDHAF2 are far less frequently observed. A total of 1045 DNA samples from Dutch paraganglioma and pheochromocytoma patients and their relatives were analyzed for mutations of SDHB, SDHC, SDHD or SDHAF2. Mutations in these genes were identified in 690 cases, 239 of which were index cases. The vast majority of mutation carriers had a mutation in SDHD (87.1%). The second most commonly affected gene was SDHAF2 (6.7%). Mutations in SDHB were found in only 5.9% of samples, whereas SDHC mutations were found in 0.3% of samples. Remarkably, 69.1% of all carriers of a mutation in an SDH gene in the Netherlands can be attributed to a single founder mutation in SDHD, c.274G>T and p.Asp92Tyr. Moreover, 88.8% of all SDH mutation carriers carry one of just six Dutch founder mutations in SDHB, SDHD and SDHAF2. The dominance of SDHD mutations is unique to the Netherlands, contrasting with the higher prevalence of SDHB mutations found elsewhere. In addition, we found that most SDH mutation-related paragangliomas-pheochromocytomas in the Netherlands can be explained by only six founder mutations in SDHAF2, SDHB and SDHD. The findings underline the regional differences in the SDH mutation spectrum, differences that should be taken into account in the development of effective screening protocols. The results show the crucial role that demographic factors play in the frequency of gene mutation

MUTYH gene variants and breast cancer in a Dutch case-control study

The MUTYH gene is involved in base excision repair. MUTYH mutations predispose to recessively inherited colorectal polyposis and cancer. Here, we evaluate an association with breast cancer (BC), following up our previous finding of an elevated BC frequency among Dutch bi-allelic MUTYH mutation carriers. A case–control study was performed comparing 1,469 incident BC patients (ORIGO cohort), 471 individuals displaying features suggesting a genetic predisposition for BC, but without a detectable BRCA1 or BRCA2 mutation (BRCAx cohort), and 1,666 controls. First, for 303 consecutive patients diagnosed before age 55 years and/or with multiple primary breast tumors, the MUTYH coding region and flanking introns were sequenced. The remaining subjects were genotyped for five coding variants, p.Tyr179Cys, p.Arg309Cys, p.Gly396Asp, p.Pro405Leu, and p.Ser515Phe, and four tagging SNPs, c.37-2487G>T, p.Val22Met, c.504+35G>A, and p.Gln338His. No bi-allelic pathogenic MUTYH mutations were identified. The pathogenic variant p.Gly396Asp and the variant of uncertain significance p.Arg309Cys occurred twice as frequently in BRCAx subjects as compared to incident BC patients and controls (p=0.13 and p=0.15, respectively). The likely benign variant p.Val22Met occurred less frequently in patients from the incident BC (p=0.03) and BRCAx groups (p=0.11), respectively, as compared to the controls. Minor allele genotypes of several MUTYH variants showed trends towards association with lobular BC histology. This extensive case–control study could not confirm previously reported associations of MUTYH variants with BC, although it was too small to exclude subtle effects on BC susceptibility

Clinical aspects of SDHA-related pheochromocytoma and paraganglioma; a nationwide study

Otorhinolaryngolog