Expanding the understanding of telomere biology disorder with reports from two families harboring variants in ZCCHC8 and TERC

Telomere biology disorder (TBD) can present within a wide spectrum of symptoms ranging from severe congenital malformations to isolated organ dysfunction in adulthood. Diagnosing TBD can be challenging given the substantial variation in symptoms and age of onset across generations. In this report, we present two families, one with a pathogenic variant in ZCCHC8 and another with a novel variant in TERC. In the literature, only one family has previously been reported with a ZCCHC8 variant and TBD symptoms. This family had multiple occurrences of pulmonary fibrosis and one case of bone marrow failure. In this paper, we present a second family with the same ZCCHC8 variant (p.Pro186Leu) and symptoms of TBD including pulmonary fibrosis, hematological disease, and elevated liver enzymes. The suspicion of TBD was confirmed with the measurement of short telomeres in the proband. In another family, we report a novel likely pathogenic variant in TERC. Our comprehensive description encompasses hematological manifestations, as well as pulmonary and hepatic fibrosis. Notably, there are no other reports which associate this variant to disease. The families expand our understanding of the clinical implications and genetic causes of TBD.

Progress report: Peutz-Jeghers syndrome

Peutz-Jeghers syndrome is a rare, autosomal dominant polyposis syndrome. Presenting with a remarkable phenotype including development of characteristic gastrointestinal polyps, mucocutaneous pigmentations, and an increased risk of cancer, the syndrome has been subject to many studies concerning the natural course of disease. In most patients, pathogenic germline variants are detected in the STK11 gene including cases of mosaicism and structural variants. Yet, studies assessing the effect of surveillance, understanding of cancer development, as well as clinical studies evaluating chemoprevention are lacking. In addition, the impact of Peutz-Jeghers syndrome on mental health, education, and family planning are insufficiently addressed. In this progress report, we describe current knowledge, clinical phenotype, surveillance strategies, and future areas of research.

Re-evaluating the genotypes of patients with adenomatous polyposis of unknown etiology: a nationwide study

In the Danish Polyposis Register, patients with over 100 cumulative colorectal adenomas of unknown genetic etiology, named in this study colorectal polyposis (CP), is registered and treated as familial adenomatous polyposis (FAP). In this study, we performed genetic analyses, including whole genome sequencing (WGS), of all Danish patients registered with CP and estimated the detection rate of pathogenic variants (PV). We identified 231 families in the Polyposis Register, 31 of which had CP. A polyposis-associated gene panel was performed and, if negative, patients were offered WGS and screening for mosaicism in blood and/or adenomas. Next-generation sequencing (NGS) was carried out for 27 of the families (four declined). PVs were detected in 11 families, and WGS revealed three additional structural variants in APC. Mosaicism of a PV in APC was detected in two families. As the variant detection rate of eligible families was 60%, 93% of families in the register now have a known genetic etiology.

Psychiatric and Educational Aspects of Familial Adenomatous Polyposis: A Nationwide Danish Cohort Study With Matched Nonexposed Individuals

INTRODUCTION

Familial adenomatous polyposis (FAP) is an autosomal, dominantly inherited disorder that predisposes to colorectal cancer. An increased risk of cancer may affect mental health, but the magnitude of this effect remains unknown. We assessed the psychosocial functioning, including the educational level attained and risk of psychiatric comorbidity, of patients with FAP by comparing them with matched nonexposed individuals.

METHODS

All Danish patients with FAP diagnosed before April 2021 were identified in the Danish Polyposis Register and paired with 4 matched nonexposed individuals. Educational history, psychiatric contacts or diagnoses ( International Classification of Disease, 10th Revision ), and treatment with antidepressants, anxiolytics, or antipsychotics were compared between patients with FAP and nonexposed individuals.

RESULTS

The analysis included 445 patients with FAP and 1,538 nonexposed individuals. The highest educational level reached was significantly lower for patients with FAP ( P < 0.001). When comparing patients with FAP and nonexposed and adjusting for a cancer diagnosis, an increased risk was observed for a psychiatric contact (1.69, 95% confidence interval [CI] 1.25-2.29, P < 0.001), any psychiatric prescription (1.39, 95% CI 1.17-1.66, P < 0.001), a psychiatric diagnosis (1.64, 95% CI 1.19-2.26, P = 0.002), and experiencing any psychiatric event (hazard ratio 1.42, 95% CI 1.20-1.68, P < 0.001). An increased risk was specifically seen for mood (affective) disorders (1.76, 95% CI 1.09-2.83, P = 0.02) and behavioral and emotional disorders (2.01, 95% CI 1.10-3.69, P = 0.02) and the need for antidepressants (1.59, 95% CI 1.24-2.03, P < 0.001) and antipsychotics (1.85, 95% CI 1.26-2.70, P = 0.002).

DISCUSSION

Compared with nonexposed individuals, patients with had significantly less education and an increased risk of developing mood and behavioral disorders, with an increased likelihood of needing antidepressants and antipsychotics.

CUX1-related neurodevelopmental disorder: deep insights into phenotype-genotype spectrum and underlying pathology

Heterozygous, pathogenic CUX1 variants are associated with global developmental delay or intellectual disability. This study delineates the clinical presentation in an extended cohort and investigates the molecular mechanism underlying the disorder in a Cux1+/- mouse model. Through international collaboration, we assembled the phenotypic and molecular information for 34 individuals (23 unpublished individuals). We analyze brain CUX1 expression and susceptibility to epilepsy in Cux1+/- mice. We describe 34 individuals, from which 30 were unrelated, with 26 different null and four missense variants. The leading symptoms were mild to moderate delayed speech and motor development and borderline to moderate intellectual disability. Additional symptoms were muscular hypotonia, seizures, joint laxity, and abnormalities of the forehead. In Cux1+/- mice, we found delayed growth, histologically normal brains, and increased susceptibility to seizures. In Cux1+/- brains, the expression of Cux1 transcripts was half of WT animals. Expression of CUX1 proteins was reduced, although in early postnatal animals significantly more than in adults. In summary, disease-causing CUX1 variants result in a non-syndromic phenotype of developmental delay and intellectual disability. In some individuals, this phenotype ameliorates with age, resulting in a clinical catch-up and normal IQ in adulthood. The post-transcriptional balance of CUX1 expression in the heterozygous brain at late developmental stages appears important for this favorable clinical course.

TINF2 is a major susceptibility gene in Danish patients with multiple primary melanoma

TINF2 encodes the TINF2 protein, which is a subunit in the shelterin complex critical for telomere regulation. Three recent studies have associated six truncating germline variants in TINF2 that have previously been associated with a cancer predisposition syndrome (CPS) caused by elongation of the telomeres. This has added TINF2 to the long telomere syndrome genes, together with other telomere maintenance genes such as ACD, POT1, TERF2IP, and TERT. We report a clinical study of 102 Danish patients with multiple primary melanoma (MPM) in which a germline truncating variant in TINF2 (p.(Arg265Ter)) was identified in four unrelated participants. The telomere lengths of three variant carriers were >90% percentile. In a routine diagnostic setting, the variant was identified in two more families, including an additional MPM patient and monozygotic twins with thyroid cancer and other cancer types. A total of 10 individuals from six independent families were confirmed carriers, all with cancer history, predominantly melanoma. Our findings suggest a major role of TINF2 in Danish patients with MPM. In addition to melanoma, other cancers in the six families include thyroid, renal, breast, and sarcoma, supporting a CPS in which melanoma, thyroid cancer, and sarcoma predominate. Further studies are needed to establish the full spectrum of associated cancer types and characterize lifetime cancer risk in carriers.

Whole genome sequencing and disease pattern in patients with juvenile polyposis syndrome: a nationwide study

Juvenile polyposis syndrome (JPS) is a hereditary hamartomatous polyposis syndrome characterized by gastrointestinal juvenile polyps and increased risk of gastrointestinal cancer. Germline pathogenic variants are detected in SMAD4 or BMPR1A, however in a significant number of patients with JPS, the etiology is unknown. From Danish registers, and genetic department and laboratories, we identified all patients in Denmark with a clinical diagnosis of JPS and/or a pathogenic variant in BMPR1A or SMAD4. In patients where no variant had been detected, we performed genetic analysis, including whole genome sequencing. We collected clinical information on all patients to investigate the phenotypic spectrum. Sixty-six patients (mean age 40 years) were included of whom the pathogenic variant was unknown in seven patients. We detected a pathogenic variant in SMAD4 or PTEN in additional three patients and thus ≈ 95% of patients had a pathogenic germline variant. Endoscopic information was available in fifty-two patients (79%) and of these 31 (60%) fulfilled the clinical criteria of JPS. In 41 patients (79%), other types of polyps than juvenile had been removed. Our results suggest that almost all patients with a clinical diagnosis of JPS has a pathogenic variant in mainly BMPR1A, SMAD4, and more rarely PTEN. However, not all patients with a pathogenic variant fulfil the clinical criteria of JPS. We also demonstrated a wide clinical spectrum, and that the histopathology of removed polyps varied.

Identification of a novel pathogenic deep intronic variant in PTEN resulting in pseudoexon inclusion in a patient with juvenile polyps

Colorectal, hamartomatous juvenile polyps occur as part of different hereditary syndromes, including Juvenile polyposis syndrome and PTEN-hamartoma tumour syndrome. However, based on clinical manifestations alone, it is difficult to differentiate between the syndromes, and genetic analysis with an NGS-panel is often used to aid diagnostics. We report a 59-year-old male with colorectal juvenile polyps, who had been referred to genetic testing but had normal genetic analysis. He did not fulfil the clinical criteria of PTEN- hamartoma tumour syndrome, but the clinical criteria of Juvenile polyposis syndrome. With Whole Genome Sequencing we detected a novel intronic variant of unknown significance in PTEN (NC_000010.11:g.89687361 A > G(chr10, hg19), NM_000314.8:c.209 + 2047 A > G). RNA analysis classified the variant as likely pathogenic as it results in a pseudoexon inclusion introducing a frameshift and a premature stop codon. The patient was then diagnosed with PTEN-hamartoma Tumour syndrome. To our knowledge this is the first report of a variant resulting in pseudoexon inclusion in PTEN.

Cancer risk and mortality in patients with solitary juvenile polyps-A nationwide cohort study with matched controls

INTRODUCTION

The risk of cancer in patients with solitary colorectal juvenile polyps (JPs) is poorly investigated and several studies have reported polyps with dysplastic and adenomatous alterations. We aimed to investigate the long-term risk of cancer and mortality in these patients by merging data from national registers and comparing them to a matched control cohort.

MATERIALS AND METHODS

Patients with a solitary JP were identified in The Danish National Pathology Register and Data Bank (DNPR). The included patients were matched on sex, age, and place of birth with 50 controls. The groups were then analyzed for risk of cancer using the Danish Cancer Registry and mortality using the Danish Cause of Death Registry.

RESULTS

We identified 1781 patients with solitary JPs and matched them with 83,713 controls. The mean follow-up time was 7.65 years for cases and 7.36 years for controls. The risk of cancer, including colorectal cancer, did not differ for the two groups and when adjusting for sex and year of birth, the hazard ratio (HR) was 1.15 (confidence interval [CI] 95% 0.94-1.41, p = 0.162). There was no increased risk of death (HR: 1.07, CI 95% 0.88-1.30, p = 0.486). The risk did not differ for different age groups or sex.

CONCLUSION

There is no increased risk of cancer or mortality for patients with solitary colorectal JPs. Thus, endoscopic follow-up may be safely omitted in these patients.

Is punctate palmoplantar keratoderma type 1 associated with malignancy? A systematic review of the literature

BACKGROUND

An association between punctate palmoplantar keratoderma type 1 (PPPK1) and malignancy has been proposed for decades. Some authors suggest that individuals with PPPK1 should undergo screening for various types of malignancies while others caution that an association is not well-established. In this systematic review, we summarized and evaluated the current evidence for a possible association between PPPK1 and malignancy.

METHODS

The review was conducted along PRISMA guidelines. The search used Embase, MEDLINE, Scopus, and the Human Gene Mutation Database up to March 2022. All studies reporting on individuals with the diagnosis of PPPK1 with or without history of malignancy were included. Two authors screened for eligible studies, extracted predefined data, and performed a quality assessment.

RESULTS

Of 773 studies identified, 45 were included. Most studies were reports on single families (24 of 45 studies) or multiple families (10 of 45 studies). The number of index cases with PPPK1 across all included studies was 280, and when family members reported with PPPK1 were added, a total of 817 individuals were identified. Overall, 23 studies reported on individuals with PPPK1 with a history of malignancy, whereas 22 studies reported on individuals with PPPK1 without a history of malignancy. Although the extracted data were not considered to be of sufficient quality to synthesize and answer our research question, the review did not confirm an association between PPPK1 and malignancy.

CONCLUSION

This review shows that there is a lack of well-designed studies on this topic to conclude whether individuals with PPPK1 have an increased risk of malignancy. Based on the present literature, however, we could not confirm an association between PPPK1 and malignancy and find it highly questionable if patients with PPPK1 should be offered surveillance for malignancies.

Cancer in Patients With Familial Adenomatous Polyposis: A Nationwide Danish Cohort Study With Matched Controls

BACKGROUND & AIMS

Familial adenomatous polyposis (FAP) is a hereditary disorder that predisposes patients to colorectal cancer (CRC). Prophylactic colectomy has greatly reduced the risk of CRC. However, new associations between FAP and the risk of other cancers have subsequently emerged. In this study, we assessed the risk of specific primary and secondary cancers among patients with FAP compared with matched controls.

METHODS

All known patients with FAP up until April 2021 were identified in the nationwide Danish Polyposis Register and paired with 4 unique controls matched by birth year, sex, and postal code. The risk of overall cancers, specific cancer types, and risk of a second primary cancer was assessed and compared with controls.

RESULTS

The analysis included 565 patients with FAP and 1890 controls. The overall risk of cancer was significantly higher for patients with FAP than for controls (hazard ratio [HR], 4.12; 95% confidence interval [CI], 3.28-5.17; P < .001). The increased risk was mainly due to CRC (HR, 4.61; 95% CI, 2.58-8.22; P < .001), pancreatic cancer (HR, 6.45; 95% CI, 2.02-20.64; P = .002), and duodenal/small-bowel cancer (HR, 14.49; 95% CI, 1.76-119.47; P = .013), whereas no significant difference was observed for gastric cancer (HR, 3.29; 95% CI, 0.53-20.23; P = .20). Furthermore, the risk of a second primary cancer was significantly higher for patients with FAP (HR, 1.89; 95% CI, 1.02-3.50; P = .042). Between 1980 and 2020, the risk of cancer among patients with FAP decreased by ∼50%.

CONCLUSIONS

Despite an absolute reduction in the risk of developing cancer among patients with FAP, the risk remained significantly higher than for the background population due to colorectal, pancreatic, and duodenal/small-bowel cancers.

Size matters in telomere biology disorders ‒ expanding phenotypic spectrum in patients with long or short telomeres

The end of each chromosome consists of a DNA region termed the telomeres. The telomeres serve as a protective shield against degradation of the coding DNA sequence, as the DNA strand inevitably ‒ with each cell division ‒ is shortened. Inherited genetic variants cause telomere biology disorders when located in genes (e.g. DKC1, RTEL1, TERC, TERT) playing a role in the function and maintenance of the telomeres. Subsequently patients with telomere biology disorders associated with both too short or too long telomeres have been recognized. Patients with telomere biology disorders associated with short telomeres are at increased risk of dyskeratosis congenita (nail dystrophy, oral leukoplakia, and hyper- or hypo-pigmentation of the skin), pulmonary fibrosis, hematologic disease (ranging from cytopenia to leukemia) and in rare cases very severe multiorgan manifestations and early death. Patients with telomere biology disorders associated with too long telomeres have in recent years been found to confer an increased risk of melanoma and chronic lymphocytic leukemia. Despite this, many patients have an apparently isolated manifestation rendering telomere biology disorders most likely underdiagnosed. The complexity of telomere biology disorders and many causative genes makes it difficult to design a surveillance program which will ensure identification of early onset disease manifestation without overtreatment.

Survival, surveillance, and genetics in patients with Peutz-Jeghers syndrome: A nationwide study

Peutz-Jeghers syndrome (PJS) is an autosomal dominant hereditary polyposis syndrome causing increased morbidity and mortality due to complications of polyposis and the development of cancer. STK11 is the only gene known to be associated with PJS, although in 10%-15% of patients fulfilling the diagnostic criteria no pathogenic variant (PV) is identified. The primary aim of this study was to identify the genetic etiology in all known PJS patients in Denmark and to estimate the risk of cancer, effect of surveillance and overall survival. We identified 56 patients (2-83 years old) with PJS. The detection rate of PVs was 96%, including three cases of mosaicism (6%). In two patients a variant was not detected. At the age of 40 years, the probabilities of cancer and death were 21% and 16%, respectively; at the age of 70 years these probabilities were 71% and 69%. Most cases of cancer (92%) were identified between the scheduled examinations in the surveillance program. These observations emphasize that PJS should be regarded as a general cancer predisposition syndrome, where improvement of clinical care is needed.

Preimplantation genetic testing in two Danish couples affected by Peutz-Jeghers syndrome

BACKGROUND

Guidelines from the European Hereditary Tumor Group as well as The Danish National Guidelines for Peutz-Jeghers Syndrome (PJS) state that both prenatal diagnosis and preimplantation genetic testing for monogenic disorders (PGT-M) should be offered to patients with PJS. However, only a few cases resulting in viable pregnancies have been published.

OBJECTIVE

We present two cases of PJS patients going through PGT-M for PJS. We highlight the awareness of this possibility and discuss the technical and ethical challenges of performing PGT-M for PJS.

METHODS AND RESULTS

Case 1: A 36-year-old male with PJS and his partner were referred for genetic counseling. The patient carried a pathogenic de novo variant in STK11. After a terminated pregnancy of a fetus carrying the same pathogenic variant, microsatellite polymorphic marker analysis was established, and the patient was offered PGT-M. The female partner of the patient gave birth to a healthy boy after five years of fertility treatment. Case 2: A 35-year-old female with PJS and her partner were referred for genetic counseling. She carried an inherited pathogenic STK11 variant. The couple was offered PGT-M. Genetic testing of the embryos was performed using microsatellite polymorphic markers. After two rounds of oocyte extraction a blastocyst predicted not to be affected by PJS was identified. The blastocyst was transferred; however, this did not result in a viable pregnancy.

CONCLUSIONS

PGT-M can be offered to patients with PJS. The process may be long and filled with ethical dilemmas requiring patients to be motivated and persistent.

Hereditary polyposis syndromes remain a challenging disease entity: Old dilemmas and new insights

In this editorial we present an overview and insights of the management of hereditary polyposis syndromes. The primary focus was on familial adenomatous polyposis, juvenile polyposis syndrome and Peutz-Jegher syndrome. Genetic testing has become increasingly available and is easier than ever to integrate into clinical practice. Furthermore, several genes have been added to the expanding list of genes associated with hereditary polyposis syndromes, allowing for precise diagnostics and tailored follow-up. Endoscopic evaluation of patients with hereditary polyposis syndromes is paramount in the surveillance strategies. Current endoscopic procedures include both diagnostic procedures and surveillance as well as therapeutic interventions. Recommendations for endoscopic procedures in the upper and lower gastrointestinal canal were described. Surgery is still a key component in the management of patients with hereditary polyposis syndromes. The increased cancer risk in these patients often render prophylactic procedures or intended curative procedures in the case of cancer development. Surgical interventions in the upper and lower gastrointestinal canal were described with relevant considerations. Development of chemopreventive medications is ongoing. Few drugs have been investigated, including nonsteroidal anti-inflammatory drugs. It has been demonstrated that cyclooxygenase-2 inhibitors may lower the number of polyps. Other medications are currently under investigation, but none have, to date, consistently been able to prevent development of disease.

Distinct gastric phenotype in patients with pathogenic variants in SMAD4: A nationwide cross-sectional study

Background and study aims  In most patients with juvenile polyposis Syndrome, it is possible to detect a pathogenic germline variant in SMAD4 or BMPR1A . It is well known that patients with a pathogenic variant in SMAD4 have a higher risk of gastric polyposis and gastric cancer compared to BMPR1A carriers, but the natural history of gastric involvement is poorly described. We aimed to systematically review endoscopic and histopathological gastric findings in Danish patients with pathogenic variants in SMAD4. Patients and methods  This was a retrospective, cross-sectional study including endoscopic and histological gastric findings in all known Danish patients with pathogenic variants in SMAD4 . The patients were identified by data from various registries as well as from clinical genetic departments and laboratories. Results  We identified 41 patients (2-72 years) with a pathogenic SMAD4 variant . In 31 patients, we were able to retrieve information on upper gastrointestinal endoscopy. Eighty-seven percent had at least one gastric abnormality including erythema (72 %) and edema (72 %). Half of the patients also had vulnerability of the mucosa and 68 % had gastric polyposis. An increasing frequency of abnormalities were observed with increasing age. Gastric cancer was diagnosed in 5 % of the cases and 22 % had a gastrectomy mainly because of massive polyposis. Conclusions  This study showed that most patients with pathogenic SMAD4 variants have a distinct phenotype of the gastric mucosa, and with an increasing severity in the elderly patients. These findings provide new insights into the natural history of gastric manifestations in patients with pathogenic SMAD4 variants.

Intestinal and extraintestinal neoplasms in patients with NTHL1 tumor syndrome: a systematic review

Germline biallelic pathogenic variants (PVs) in NTHL1 have since 2015 been associated with the autosomal recessive tumor predisposition syndrome: NTHL1 tumor syndrome or NTHL1-associated polyposis. In this systematic review, we aim to systematically investigate the phenotypic and genotypic spectrum of the condition including occurrence of both benign and malignant tumors. The databases PubMed, EMBASE, and Scopus were searched. The search was conducted the 25th of august 2021. We included patients with germline PVs, both heterozygous and homo-/compound heterozygous carriers. Twenty-one papers were selected including 47 patients with biallelic PVs in NTHL1 in 32 families. Twenty-three out of 47 patients (49%) were diagnosed with colorectal cancer (CRC) (mean age: 55, range: 31-73) and 12 out of 22 female patients (55%) were diagnosed with breast cancer (mean age: 49, range: 36-63). Apart from three, all patients who underwent a colonoscopy, had colonic adenomas (93%), and three patients (6%) had duodenal adenomatosis. We also identified 158 heterozygous carriers of germline PVs in NTHL1. Twenty-six out of 68 (38%) heterozygous carriers, who underwent colonoscopy, had colonic polyps or adenomas. Twenty-nine heterozygous carriers (18%) were diagnosed with CRC and 59 (49%) with breast cancer. We observed a high frequency of early onset CRC and breast cancer in patients with NTHL1 tumor syndrome. Subsequently, colorectal, breast, and endometrial cancer screening programs are recommended for NTHL1 biallelic carriers. Trial registry PROSPERO: CRD42021275159.

Hereditary haemorrhagic telangiectasia in Danish patients with pathogenic variants in SMAD4: a nationwide study

BACKGROUND AND AIMS

Hereditary haemorrhagic telangiectasia (HHT) is an autosomal dominant condition characterised by recurrent epistaxis, telangiectatic lesions in the skin and mucosal membranes, and arteriovenous malformations (AVMs) in various organs. In 3%-5% of patients, HHT is caused by pathogenic germline variants (PVs) in SMAD4, and these patients often have additional symptoms of juvenile polyposis syndrome and thoracic aneurysms. The phenotypic spectrum of SMAD4-associated HHT is less known, including the penetrance and severity of HHT. We aimed to investigate the phenotypic spectrum of HHT manifestations in Danish patients with PVs in SMAD4 and compare the findings with current literature.

METHODS

The study is a retrospective nationwide study with all known Danish patients with PVs in SMAD4. In total, 35 patients were included. The patients were identified by collecting data from genetic laboratories, various databases and clinical genetic departments across the country. Clinical information was mainly collected from the Danish HHT-Centre at Odense University Hospital.

RESULTS

Twenty-nine patients with PVs in SMAD4 (83%) were seen at the HHT-Centre. Seventy-six per cent of these fulfilled the Curaçao criteria, 86% experienced recurrent epistaxis and 83% presented with telangiectatic lesions at different anatomical localisations. Almost 60% had AVMs, mainly pulmonary and hepatic, while none was found to have cerebral AVMs. Fifteen per cent had thoracic aortic abnormalities.

CONCLUSION

We present a nationwide study of one of the largest populations of patients with PVs in SMAD4 that has systematically been examined for HHT manifestations. The patients presented the full spectrum of HHT-related manifestations and the majority fulfilled the Curaçao criteria.

[Telomere biology disorders]

The end of the chromosomes consists of DNA referred to as telomeres. The telomeres protect chromosomal DNA against shortening when cells divide. Patients with telomere biology disorders carry pathogenic germline variants in a gene involved in telomere function. New technologic advances have enabled us to identify more patients with telomere biology disorders, which in turn have increased our understanding of the phenotypic spectrum. The latter have proved wider than previously thought, and now we know that e.g. patients with isolated lung fibrosis can have an underlying telomere biology disorder.

Novel Genetic Causes of Gastrointestinal Polyposis Syndromes

Hereditary polyposis syndromes are characterized by a large number and/or histopathologically specific polyps in the gastrointestinal tract and a high risk of both colorectal cancer and extracolonic cancer at an early age. While the genes responsible for some of the syndromes, eg, APC in familial adenomatous polyposis and STK11 in Peutz-Jeghers syndrome, have been known for decades, novel genetic causes have recently been detected that have shed light on the broader clinical spectrum of syndromes. Genetic diagnoses are important because they can facilitate a personalized surveillance program. Furthermore, at-risk members of the patient's family can be tested and enrolled in surveillance as needed. In some cases, prenatal diagnostics should be offered. In this paper, we describe the development in germline genetics of the hereditary polyposis syndromes over the last 10-12 years, their clinical characteristics, as well as how to implement genetic analyses in the diagnostic pipeline.

Danish guidelines for management of non-APC-associated hereditary polyposis syndromes

Hereditary Polyposis Syndromes are a group of rare, inherited syndromes characterized by the presence of histopathologically specific or numerous intestinal polyps and an increased risk of cancer. Some polyposis syndromes have been known for decades, but the development in genetic technologies has allowed the identification of new syndromes.. The diagnosis entails surveillance from an early age, but universal guideline on how to manage and surveille these new syndromes are lacking. This paper represents a condensed version of the recent guideline (2020) from a working group appointed by the Danish Society of Medical Genetics and the Danish Society of Surgery on recommendations for the surveillance of patients with hereditary polyposis syndromes, including rare polyposis syndromes.

[New hereditary polyposis syndromes in the patient with intestinal polyps]

Hereditary polyposis syndromes (HPS) are a group of rare, inherited syndromes characterised by the presence of histopathological specific or numerous intestinal polyps and a high risk of intestinal and extraintestinal cancer. During the last decade, several new HPS have been discovered, as it is possible to detect pathogenic germline variants in genes not previously known to be associated with polyposis. This review summarises the current knowledge on the syndromes and discusses genetic testing as part of the diagnostic pipeline when suspecting a polyposis syndrome.

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.

De Novo and Bi-allelic Pathogenic Variants in NARS1 Cause Neurodevelopmental Delay Due to Toxic Gain-of-Function and Partial Loss-of-Function Effects

Aminoacyl-tRNA synthetases (ARSs) are ubiquitous, ancient enzymes that charge amino acids to cognate tRNA molecules, the essential first step of protein translation. Here, we describe 32 individuals from 21 families, presenting with microcephaly, neurodevelopmental delay, seizures, peripheral neuropathy, and ataxia, with de novo heterozygous and bi-allelic mutations in asparaginyl-tRNA synthetase (NARS1). We demonstrate a reduction in NARS1 mRNA expression as well as in NARS1 enzyme levels and activity in both individual fibroblasts and induced neural progenitor cells (iNPCs). Molecular modeling of the recessive c.1633C>T (p.Arg545Cys) variant shows weaker spatial positioning and tRNA selectivity. We conclude that de novo and bi-allelic mutations in NARS1 are a significant cause of neurodevelopmental disease, where the mechanism for de novo variants could be toxic gain-of-function and for recessive variants, partial loss-of-function.

Two cases of somatic STK11 mosaicism in Danish patients with Peutz-Jeghers syndrome

Peutz-Jeghers syndrome (PJS) is a hereditary polyposis syndrome characterized by hamartomatous Peutz-Jeghers polyps in the gastrointestinal tract, mucocutaneous pigmentations, and increased risk for intestinal and extraintestinal cancer. In more than two-third of patients it is possible to detect pathogenic variants in the serine/threonine kinase 11 (STK11) gene, but so far is knowledge about genetic causes in the remaining part of patients limited. Reports of STK11 mosaicism are rare but may be an explanation in some patients without initial findings of pathogenic variants in STK11. We report two Danish patients with STK11 mosaicism detected in blood when using Next-Generation Sequencing. This is only the sixth and seventh patient reported in the literature, and we compare phenotypes of the reported cases. The results indicate that STK11 mosaicism is more frequent than anticipated and highlight that mosaicism should be considered in patients with clinical suspicion of PJS or patients fulfilling the diagnostic criteria.

Revised Danish guidelines for the cancer surveillance of patients with Cowden Syndrome

INTRODUCTION

Cowden syndrome is a cancer predisposition syndrome caused by pathogenic variants in PTEN. The affected patients possess an increased risk of breast, thyroid, renal, colorectal, endometrial cancers as well as malignant melanoma. Thus prophylactic surveillance and follow up is crucial for these patients.

METHODS

A review of the literature including existing guidelines from the years 1996 until 2017 was carried out. In total, 2078 scientific papers were identified through database searches on Cowden syndrome. Among these, 11 manuscripts were included based on scientific relevance and quality. Expert consensus was reached to define management guidelines.

RESULTS

The literature revealed a high risk of cancer in specific organs for patients diagnosed with Cowden Syndrome. Alternative management guidelines were proposed and discussed.

CONCLUSIONS

Here we propose a revised set of management guidelines for patients with Cowden syndrome in Denmark to address the increased risk of various cancer types.

[X-chromosome loss can be an age-related phenomenon in women]

During chromosome analysis the finding of few cells with X-chromosome aneuploidy in a phenotypically normal woman is not unusual - so-called low-grade mosaicism for X aneuploidy (LLX-A). Such results can be difficult to interpret. In this review, LLX-A and its clinical implications are discussed, and based on the current literature it can be concluded, that LLX-A is an age-related phenomenon not related to reproductive issues such as recurrent abortions. This should be taken into account in any laboratory performing chromosome analysis.

Germline variants in Hamartomatous Polyposis Syndrome-associated genes from patients with one or few hamartomatous polyps

OBJECTIVE

A subgroup of patients with hamartomatous polyps in the GI tract has a hereditary Hamartomatous Polyposis Syndrome with an increased risk of cancer. The distinction between patients with one or few polyps and patients with a syndrome can be difficult. A pathogenic germline mutation can be detected in a majority of HPS patients. This study investigates whether patients with one or few hamartomatous polyps could have a syndrome based on genetic screening of relevant genes.

METHODS

We designed a gene panel including 26 hamartomatous polyposis-associated genes. Using targeted Next Generation Sequencing, DNA samples from 77 patients with 84 hamartomatous polyps were sequenced. The detected germline variants were classified into pathogenicity classes.

RESULTS

We detected several germline variants, among them three in ENG, two in BMPR1A, one in PTEN, and one in SMAD4. Although some of the detected variants have been reported previously none could be definitely pathogenic or likely pathogenic.

CONCLUSIONS

Our study points towards that genetic testing for the Hamartomatous Polyposis Syndromes in patients with one or few polyps does not improve diagnostics, however we illustrate that the clinical significance of genetic variants can be difficult to interpret. A family history of polyps, cancer, or extraintestinal findings or a minimum of 3-5 polyps seems to be relevant information to include before genetic testing.

Hamartomatous polyps - a clinical and molecular genetic study

Hamartomatous polyps (HPs) in the gastrointestinal (GI) tract are rare compared to other types of GI polyps, yet they are the most common type of polyp in children. The symptoms are usually rectal bleeding, abdominal pain, obstipation, anaemia, and/or small bowel obstruction. The polyps are typically removed concurrently with endoscopy when located in the colon, rectum, or stomach, whereas polyps in the small bowel are removed during push-enteroscopy, device-assisted enteroscopy, or by surgery. HPs can be classified as juvenile polyps or Peutz-Jeghers polyps based on their histopathological appearance. Patients with one or a few juvenile polyps are usually not offered clinical follow-up as the polyp(s) are considered not to harbour any malignant potential. Nevertheless, it is important to note that juvenile polyps and HPs are also found in patients with hereditary hamartomatous polyposis syndromes (HPS). Patients with HPS have an increased risk of cancer, recurrences of polyps, and extraintestinal complications. The syndromes are important to diagnose, as patients should be offered surveillance from childhood or early adolescence. The syndromes include juvenile polyposis syndrome, Peutz-Jeghers syndrome, and the PTEN hamartoma tumour syndrome. Currently, the HPS diagnoses are based on clinical criteria and are often assisted with genetic testing as candidate genes have been described for each syndrome. This thesis is based on six scientific papers. The overall aim of the studies was to expand the knowledge on clinical course and molecular genetics in patients with HPs and HPS, and to investigate research participants' attitude towards the results of extensive genetic testing.   Paper I: In the first paper we investigated the occurrence, anatomic distribution, and other demographics of juvenile polyps in the colon and rectum in Denmark in 1995-2014. Based on the Danish Pathology Data Bank we found that 1772 patients had 2108 JPs examined in the period, and we calculated the incidence of juvenile polyps to be between 1:45,000 and 1:65,000. The majority of patients with juvenile polyps were adults and 1% fulfilled to diagnostic criteria of JPS. The majority of patients had a single juvenile polyp. Paper II: In this paper we conducted a review of the HPS based on the current literature. Paper III: We investigated the hypothesis that patients with one or few HPs may have a HPS based on genetic screening. We de-signed a panel of 26 genes associated with HPS and used targeted next generation sequencing in 77 patients with mainly one juvenile polyp. We detected several germ line variants, among them three in ENG, two in BMPR1A, one in PTEN, and one in SMAD4. Although some of the detected variants have been reported previously none could be classified as definitely pathogenic or likely pathogenic according to our variant classification scheme and thus we concluded that genetic screening of patients with one or few JPs are not indicated. Paper IV: In Paper IV we investigated one of the ethical aspects of next generation sequencing: the issue whether research participants in NGS studies should be offered the possibility of not re-ceiving information on incidental genetic findings (the "opting out possibility"). We conducted semi-structures interviews in 127 research participants, and found that the majority (61%) wanted information on all incidentals findings, while 36% wanted information on actionable incidental findings. Only 3% did not want information on incidental findings at all. Paper V: In this paper we wanted to gather information on all Danish patients with Peutz-Jeghers syndrome in order to investigate the phenotype and genotype. Through Danish registers we detected 43 patients of which 14 had deceased. We calculated the prevalence of Peutz-Jeghers syndrome to be approximately one in 195,000 individuals. The median age at diagnosis was 29 years with obstruction of the small bowel as the most frequent presenting symptom. We noted 18 cancer occurrences in the population in both the GI tract and at extraintestinal sites, demonstrating that these patients are predisposed to cancer at various anatomical sites. The study also underlined the wide phenotypic expression of the syndrome.   Paper VI: In the last paper we identified patients with juvenile polyposis syndrome, who carry a SMAD4 mutation, and described their genotype and phenotype. We especially investigated whether these patients have symptoms of both juvenile polyposis syndrome and hereditary hemorrhagic telangiectasia. We identified 14 Danish patients. Most of these had symptoms of both conditions and one had aortic root dilatation. Thus, this group of patients requires a multidisciplinary follow-up program.

Disease pattern in Danish patients with Peutz-Jeghers syndrome

PURPOSE

In this paper, we aimed to collect genetic and medical information on all Danish patients with Peutz-Jeghers syndrome (PJS), in order to contribute to the knowledge of phenotype and genotype. Peutz-Jeghers syndrome is a hereditary syndrome characterized by multiple hamartomatous polyps in the GI tract, mucocutaneous pigmentations, and an increased risk of cancer in the GI tract and at extraintestinal sites. Over 90 % of patients harbour a pathogenic mutation in STK11.

METHODS

Based on the Danish Pathology Data Bank, the Danish National Patient Register, as well as information from relevant departments at Danish hospitals, we identified patients and collected clinical and genetic information.

RESULTS

We identified 43 patients of which 14 were deceased. The prevalence was estimated to be ∼1 in 195,000 individuals. The median age at first symptom was 27.5 with invagination of the small bowel as the most frequent presenting symptom. We noted 18 occurrences of cancer at various anatomical sites, including a case of thyroid cancer and penile cancer. Eight of the deceased patients had died of cancer. Eighteen different mutations in STK11 had been detected in 28 patients.

CONCLUSION

This is the first comprehensive study of patients with Peutz-Jeghers syndrome in the Danish population identified from nationwide registers and databases. We have demonstrated that the expressivity of Peutz-Jeghers syndrome varies greatly among the patients, even within the same families, underlining the great phenotypic spectrum. Patients with PJS should be offered surveillance from childhood in order to prevent morbidity and reduce mortality.

[Noonan syndrome can be diagnosed clinically and through molecular genetic analyses]

Noonan syndrome is part of the group of RASopathies caused by germ line mutations in genes involved in the RAS/MAPK pathway. There is substantial phenotypic overlap among the RASopathies. Diagnosis of Noonan syndrome is often based on clinical features including dysmorphic facial features, short stature and congenital heart disease. Rapid advances in sequencing technology have made molecular genetic analyses a helpful tool in diagnosing and distinguishing Noonan syndrome from other RASopathies.

[Patients with basal cell naevus syndrome should be offered an early multidisciplinary follow-up and treatment]

Basal cell naevus syndrome (Gorlin-Goltz syndrome) is a rare, autosomal dominantly inherited condition with a wide range of developmental and multiple organ-related anomalies. Cardinal features include multiple basal cell carcinomas, jaw cysts, palmoplantar pits and calcification of the falx cerebri. Other important clinical features are skeletal abnormalities and facial dysmorphism including macrocephaly. Germ-line mutations are found in PTCH1. Management of the syndrome requires a multidisciplinary approach, and in this article management guidelines are reviewed and discussed.

Research participants in NGS studies want to know about incidental findings

Following the implementation of high-throughput sequencing legal and ethical issues are discussed intensively. The management of incidental findings (IFs) in a research setting have been investigated but there is a lack of literature concerning research participant's perspective. The aim of this study was to investigate whether research participants want disclosure of IFs and what kind of IFs they want to know about. One hundred and twenty-seven research participants in a study of gastrointestinal polyps were informed about whole-exome sequencing and the risk of IFs. They were asked to decide whether they (A) wanted disclosure of IFs no matter whether the variants were associated with a non-treatable or non-preventable condition, (B) wanted disclosure of variants associated with treatable or preventable conditions or (C) wanted no disclosure at all. Participants who wanted disclosure of all the IFs (A) accounted for the majority (n=78), 45 of the participants only wanted disclosure of variants, which could lead to surveillance or treatment (B) and 4 participants did not want IFs to be disclosed at all (C). The study showed that almost all research participants wanted disclosure of at least some types of IFs.

[Juvenile polyposis syndrome and hereditary haemorrhagic telangiectasia syndrome in a patient a with SMAD4 mutation]

Germ line mutations in SMAD4 can cause both juvenile polyposis syndrome and hereditary haemorrhagic telangiectasia syndrome. In this case we present a 37-year-old man with a frameshift mutation in SMAD4. The patient had multiple polyps in the gastrointestinal tract and was diagnosed with colon cancer at the age of 21 and gastro-oesophageal junction cancer at the age of 37. Furthermore the patient had telangiectasias and recurrent epistaxis.

[Juvenile polyposis syndrome is a rare cause of gastrointestinal cancer]

Juvenile polyposis syndrome is an autosomal dominant polyposis syndrome. It is characterized by predisposition to multiple juvenile polyps in the gastrointestinal tract and is associated with an increased risk of colorectal and ventricular cancer. Patients and at risk family members should be offered surveillance. This article discusses clinical features and surveillance based on the current literature.

Hamartomatous polyposis syndromes: a review

Hamartomatous Polyposis Syndromes (HPS) are genetic syndromes, which include Peutz-Jeghers syndrome, Juvenile polyposis syndrome, PTEN hamartoma tumour syndrome (Cowden Syndrom, Bannayan-Riley-Ruvalcaba and Proteus Syndrome) as well as hereditary mixed polyposis syndrome. Other syndromes such as Gorlin Syndrome and multiple endocrine neoplasia syndrome 2B are sometimes referred to as HPS. HPS is characterized by the development of hamartomatous polyps in the gastrointestinal tract as well as several extra-intestinal findings such as dermatological and dysmorphic features or extra-intestinal cancer. The syndromes are rare and inherited in an autosomal dominant manner.

The diagnosis of HPS has traditionally been based on clinical criteria, but can sometimes be difficult as the severity of symptoms range considerably from only a few symptoms to very severe cases - even within the same family. De novo cases are also frequent. However, because of the discovery of several associated germline-mutations as well as the rapid development in genetics it is now possible to use genetic testing more often in the diagnostic process. Management of the syndromes is different for each syndrome as extra-intestinal symptoms and types of cancers differs.

Clinical awareness and early diagnosis of HPS is important, as affected patients and at-risk family members should be offered genetic counselling and surveillance. Surveillance in children with HPS might prevent or detect intestinal or extra-intestinal complications, whereas in adulthood surveillance is recommended due to an increased risk of cancer e.g. intestinal cancer or breast cancer.

[Juvenile polyposis syndrome is a rare cause of gastrointestinal cancer]

Juvenile polyposis syndrome is an autosomal dominant polyposis syndrome. It is characterized by predisposition to multiple juvenile polyps in the gastrointestinal tract and is associated with an increased risk of colorectal and ventricular cancer. Patients and at risk family members should be offered surveillance. This article discusses clinical features and surveillance based on the current literature.

Inheritance of the chronic myeloproliferative neoplasms. A systematic review

This systematic review investigated the inheritance of the classical chronic myeloproliferative neoplasms (MPNs) including polycythemia vera (PV), essential thrombocythemia (ET), primary myelofibrosis (PMF) and chronic myelogenous leukemia (CML). Sixty-one articles were included and provided 135 families with a total of 341 participants distributed to various subtypes of MPN: 50% PV, 23% ET, 14% PMF, 10% CML and 3% non-MPN hematological disorder. Women developed the disease earlier than men (43.1 years vs 47.3 years; p = 0.074), while the general average age of onset was 46 years, notably younger than sporadic cases. The clinical phenotype of the families showed a homogenous (67%) and a heterogeneous (33%) pattern, with the majority being PV-PV pairs (36%) and PV-PMF pairs (17%), respectively. This observation suggests that the susceptibility gene (or genes) is not restricted to one subtype supporting the hypothesis of a mutation in an early multipotent stem cell. Furthermore, a major subgroup of families provided evidence of an autosomal dominant (AD) inheritance with reduced penetrance. This study suggests that the origin of MPNs may occur in at least three different settings: (i) a sporadic, (ii) genetic heterogeneity with polygenetic and environmental impact and (iii) a familial phenotype following an AD inheritance.