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PURPOSE: Biallelic PIGN variants have been described in Fryns syndrome, multiple congenital anomalies-hypotonia-seizure syndrome (MCAHS), and neurologic phenotypes. The full spectrum of clinical manifestations in relation to the genotypes is yet to be reported.METHODS: Genotype and phenotype data were collated and analyzed for 61 biallelic PIGN cases: 21 new and 40 previously published cases. Functional analysis was performed for 2 recurrent variants (c.2679C>G p.Ser893Arg and c.932T>G p.Leu311Trp).RESULTS: Biallelic-truncating variants were detected in 16 patients-10 with Fryns syndrome, 1 with MCAHS1, 2 with Fryns syndrome/MCAHS1, and 3 with neurologic phenotype. There was an increased risk of prenatal or neonatal death within this group (6 deaths were in utero or within 2 months of life; 6 pregnancies were terminated). Incidence of polyhydramnios, congenital anomalies (eg, diaphragmatic hernia), and dysmorphism was significantly increased. Biallelic missense or mixed genotype were reported in the remaining 45 cases-32 showed a neurologic phenotype and 12 had MCAHS1. No cases of diaphragmatic hernia or abdominal wall defects were seen in this group except patient 1 in which we found the missense variant p.Ser893Arg to result in functionally null alleles, suggesting the possibility of an undescribed functionally important region in the final exon. For all genotypes, there was complete penetrance for developmental delay and near-complete penetrance for seizures and hypotonia in patients surviving the neonatal period.CONCLUSION: We have expanded the described spectrum of phenotypes and natural history associated with biallelic PIGN variants. Our study shows that biallelic-truncating variants usually result in the more severe Fryns syndrome phenotype, but neurologic problems, such as developmental delay, seizures, and hypotonia, present across all genotypes. Functional analysis should be considered when the genotypes do not correlate with the predicted phenotype because there may be other functionally important regions in PIGN that are yet to be discovered.

An Xq22.2 region upstream of PLP1 has been proposed to underly a neurological disease trait when deleted in 46,XX females. Deletion mapping revealed that heterozygous deletions encompassing the smallest region of overlap (SRO) spanning six Xq22.2 genes (BEX3, RAB40A, TCEAL4, TCEAL3, TCEAL1, and MORF4L2) associate with an early-onset neurological disease trait (EONDT) consisting of hypotonia, intellectual disability, neurobehavioral abnormalities, and dysmorphic facial features. None of the genes within the SRO have been associated with monogenic disease in OMIM. Through local and international collaborations facilitated by GeneMatcher and Matchmaker Exchange, we have identified and herein report seven de novo variants involving TCEAL1 in seven unrelated families: three hemizygous truncating alleles; one hemizygous missense allele; one heterozygous TCEAL1 full gene deletion; one heterozygous contiguous deletion of TCEAL1, TCEAL3, and TCEAL4; and one heterozygous frameshift variant allele. Variants were identified through exome or genome sequencing with trio analysis or through chromosomal microarray. Comparison with previously reported Xq22 deletions encompassing TCEAL1 identified a more-defined syndrome consisting of hypotonia, abnormal gait, developmental delay/intellectual disability especially affecting expressive language, autistic-like behavior, and mildly dysmorphic facial features. Additional features include strabismus, refractive errors, variable nystagmus, gastroesophageal reflux, constipation, dysmotility, recurrent infections, seizures, and structural brain anomalies. An additional maternally inherited hemizygous missense allele of uncertain significance was identified in a male with hypertonia and spasticity without syndromic features. These data provide evidence that TCEAL1 loss of function causes a neurological rare disease trait involving significant neurological impairment with features overlapping the EONDT phenotype in females with the Xq22 deletion.

The principal component of the protein homeostasis network is the ubiquitin-proteasome system. Ubiquitination is mediated by an enzymatic cascade involving, i.e. E3 ubiquitin ligases, many of which belong to the cullin-RING ligases family. Genetic defects in the ubiquitin-proteasome system components, including cullin-RING ligases, are known causes of neurodevelopmental disorders. Using exome sequencing to diagnose a pediatric patient with developmental delay, pyramidal signs and limb ataxia, we identified a de novo missense variant c.376G>C; p.(Asp126His) in the FEM1C gene encoding a cullin-RING ligase substrate receptor. This variant alters a conserved amino acid located within a highly constrained coding region and is predicted as pathogenic by most in silico tools. In addition, a de novo FEM1C mutation of the same residue p.(Asp126Val) was associated with an undiagnosed developmental disorder, and the relevant variant (FEM1CAsp126Ala) was found to be functionally compromised in vitro. Our computational analysis showed that FEM1CAsp126His hampers protein substrate binding. To further assess its pathogenicity, we used the nematode Caenorhabditis elegans. We found that the FEM-1Asp133His animals (expressing variant homologous to the FEM1C p.(Asp126Val)) had normal muscle architecture yet impaired mobility. Mutant worms were sensitive to the acetylcholinesterase inhibitor aldicarb but not levamisole (acetylcholine receptor agonist), showing that their disabled locomotion is caused by synaptic abnormalities and not muscle dysfunction. In conclusion, we provide the first evidence from an animal model suggesting that a mutation in the evolutionarily conserved FEM1C Asp126 position causes a neurodevelopmental disorder in humans.

We report on the first Polish patient diagnosed with the Aicardi-Goutières syndrome 5 (AGS5). AGS is caused by mutations in one of 9 genes (TREX1, RNASEH2A, RNASEH2B, RNASEH2C, SAMHD1, ADAR, IFIH, LSM11, RNU7-1) which stimulate the type I interferon response. The diagnosis was confirmed by identifying a compound heterozygous mutation p.(Phe165Ser)/p.(Gln235*) in the SAMHD1 gene using whole-exome sequencing. The cystic lesions in the temporal lobes are an uncommon finding in the presented patient carrying a SAMHD1 mutation. Reporting new cases expands the range of phenotypes and plays the crucial role in understanding the AGS pathogenesis and creates new therapy approaches.

IntroductionThe inactivation of both alleles of the ATM gene leads to ataxia-telangiectasia syndrome, whereas carriers of monoallelic mutations in the ATM gene are associated with increased risk of different types of cancer. Three substitutions in the ATM gene (c.6095G>A, c.7630-2A>C, c.5932G>T) are the most common mutations causing ataxia-telangiectasia among Polish patients. The aim of this study was to determine whether these ATM mutations are associated with increased risk of tobacco-related cancers.Material and methods783 Polish patients with tobacco-related cancers were included in the study (468 with lung cancer, 153 with a single laryngeal cancer, 86 with multiple primary tumors localized in the larynx and 76 multiple primary tumors localized in the head or neck). The control group consisted of 464 healthy subjects from the Polish population. Three ATM mutations – c.5932G>T, c.6095G>A, c.7630-2A>C – were tested among selected patients. Molecular analyses were performed using high resolution melting analysis and restriction fragment length polymorphism.ResultsIn the present study, we detected only one mutation, c.7630-2A>C, and no carriers of c.5932G>T, c.6095G>A mutations in the ATM gene among Polish patients with tobacco-related cancers. A patient with c.7630-2A>C mutation was diagnosed with lung adenocarcinoma, the most common type of lung cancer. One carrier of c.6095G>A mutation was found in the control group.ConclusionsThe results indicate that the studied ATM variants do not seem to be associated with tobacco-related cancers in Poland.

Indtroduction and methods: In chronic lymphocytic leukemia (CLL), molecular and cytogenetic diagnostics are crucial for the determination of accurate prognosis and treatment choice. Among different genetic aberrations, del(17p13) or TP53 mutations constitute high-risk factors, and early identification of such defects is a high priority for CLL patients. While cytogenetic diagnostics is well-established and accessible for the majority of CLL patients in Poland, molecular diagnostics of TP53 mutations is performed only in a few ERIC-certified centers (eight as of September 2020), and only two of these employ next-generation sequencing (NGS) for routine analysis of TP53 status in CLL patients. Here we report the interim results of a project assessing TP53 mutations with NGS technology in relapsed or refractory CLL patients with confirmed negative del(17p13) status. 249 patients from 32 clinical centers were included in the study. Results: NGS analysis revealed TP53 mutations in 42/249 (17%) patients, half of whom (21/249, 8.5%) had subclonal mutations (VAF ≤10%). These results are in line with published data in relapsed/refractory CLL patients. Conclusions: The results of the project demonstrated the feasibility and accuracy of NGS testing in CLL patients despite several initial logistical and technical obstacles. Our study also proved that, with appropriate funding, CLL patients from any hematological center in Poland can have access to state-of-the-art molecular diagnostics

Purpose High myopia (HM) is an eye disorder with both environmental and genetic factors involved. Many genetic factors responsible for HM were recognized worldwide, but little is known about genetic variants underlying HM in Central Europe. Thus, the aim of this study was to identify rare sequence variants involved in HM in families from Central Europe to better understand the genetic basis of HM. Materials and methods We assessed 17 individuals from 7 unrelated Central European families with hereditary HM using exome sequencing (ES). Segregation of selected variants in other available family members was performed using Sanger sequencing. Results Detected 73 rare variants were selected for verification. We observed 2 missense variants, c.938C>T in SLC35E2B - encoding solute carrier family 35 member E2B, and c.1642G>C in FLRT3 - encoding fibronectin leucine rich transmembrane protein, segregating with HM in one family. Conclusions FLRT3 ​and/or ​SLC35E2B ​could represent disease candidate genes and identified sequence variants might be responsible for HM in the studied family.

A scientific consortium led by the Central Forensic Laboratory of the Police has undertaken to develop a method for DNA analysis of the soil microbiome to be used in forensic investigations. The aim of the project entitled Soil Microbiome Analysis Forensic Tool – SMAFT (http://smaft.eu/), financed by the National Center for Research and Development (DOB-BIO10/03/01/2019), is to develop a new tool that enables the association of a trace in the form of a soil sample with a specific geographical location. The first part of the paper introduces the concept of the microbiome and presents the possibilities of using microbiome DNA analysis in forensic science. In the second part, the stages of the SMAFT project are described in detail, beginning from the collection of soil samples from different sites in Poland across all seasons and isolation of microbiome DNA through massively parallel sequencing (MPS) technology-based analysis of isolates and the development of a genetic test containing a set of metagenomic markers allowing for effective individualization of soil samples, up to the creation of an IT system enabling analysis and interpretation of the obtained results, which includes a database of soil microbiome DNA profiles from various locations in Poland.

The principal component of the protein homeostasis network is the ubiquitin-proteasome system. Ubiquitination is mediated by an enzymatic cascade involving, i.e., E3 ubiquitin ligases, many of which belong to the cullin-RING ligases family. Genetic defects in the ubiquitin-proteasome system components, including cullin-RING ligases, are known causes of neurodevelopmental disorders. Using exome sequencing to diagnose a pediatric patient with developmental delay, pyramidal signs, and limb ataxia, we identified ade novomissense variant c.376G>C; p.(Asp126His) in theFEM1Cgene encoding a cullin-RING ligase substrate receptor. This variant alters a conserved amino acid located within a highly constrained coding region and is predicted as pathogenic by mostin silicotools. In addition, ade novo FEM1Cmutation of the same residue p.(Asp126Val) was associated with an undiagnosed developmental disorder, and the relevant variant (FEM1CAsp126Ala) was found to be functionally compromisedin vitro. Our computational analysis showed that FEM1CAsp126Hishampers protein substrate binding. To further assess its pathogenicity, we used the nematodeCaenorhabditis elegans. We found that the FEM-1Asp133Hisanimals (expressing variant homologous to theFEM1Cp.(Asp126Val)) had normal muscle architecture yet impaired mobility. Mutant worms were sensitive to the acetylcholinesterase inhibitor aldicarb but not levamisole (acetylcholine receptor agonist), showing that their disabled locomotion is caused by synaptic abnormalities and not muscle dysfunction. In conclusion, we provide the first evidence from an animal model suggesting that a mutation in the evolutionarily conserved FEM1C Asp126 position causes a neurodevelopmental disorder in humans.

In this article, we report familial cases of type 2 congenital erythrocytosis (ECYT2) in two siblings, a 2-year-old boy and his younger sister. Both patients were diagnosed based on laboratory findings including erythrocytosis, elevated hemoglobin levels, and hematocrit. Acquired erythrocytosis was excluded based on the clinical features and genetic analysis of JAK2/CALR/MPL genes. Next-generation sequencing was employed for older brother revealing NM_000551.4: c.598C>T, p.Arg200Trp homozygous variant in the VHL gene, the similar variant was detected in the younger sibling. Sequencing analysis confirmed the VHL c.598C>T heterozygous variant in both parents. To the best of our knowledge, these are the first confirmed cases of familial erythrocytosis type 2, also known as Chuvash type, in Poland.

Background Myofibrillar myopathies (MFM) are a subgroup of protein aggregate myopathies (PAM) characterized by a common histological picture of myofibrillar dissolution, Z-disk disintegration, and accumulation of degradation products into inclusions. Mutations in genes encoding components of the Z-disk or Z-disk-associated proteins occur in some patients whereas in most of the cases, the causative gene defect is still unknown. We aimed to search for pathogenic mutations in genes not previously associated with MFM phenotype. Methods We performed whole-exome sequencing in four patients from three unrelated families who were diagnosed with PAM without aberrations in causative genes for MFM. Results In the first patient and her affected daughter, we identified a heterozygous p.(Arg89Cys) missense mutation in LMNA gene which has not been linked with PAM pathology before. In the second patient, a heterozygous p.(Asn4807Phe) mutation in RYR1 not previously described in PAM represents a novel, candidate gene with a possible causative role in the disease. Finally, in the third patient and his symptomatic daughter, we found a previously reported heterozygous p.(Cys30071Arg) mutation in TTN gene that was clinically associated with cardiac involvement. Conclusions Our study identifies a new genetic background in PAM pathology and expands the clinical phenotype of known pathogenic mutations.

Intracardiac tumors in children are relatively rare, but their clinical consequences may include severe outflow tract obstruction, embolism, cardiac insufficiency, or rhythm disturbances. In some cases, the tumor may constitute part of a genetic condition and prompt additional investigations, as well as a modification of therapeutic management. Herein, we present a molecularly confirmed familial case of Gorlin syndrome with an early cardiac tumor as a presenting sign. We provide detailed clinical characteristics of the affected individuals and a useful review of syndromic causes of pediatric cardiac tumors in clinical practice.

Identification of pathogens causing viral encephalitis remains challenging, and in over 50% of cases the etiologic factor remains undetermined. Next-generation sequencing (NGS) based metagenomics has been successfully used to detect novel and rare infections, but its value for routine diagnosis of encephalitis remains unclear. The aim of the present study was to determine the sensitivity of shotgun metagenomic sequencing protocols, which include preamplification, and testing it against cerebrospinal fluid (CSF) samples from encephalitis patients. For sensitivity testing HIV and HBV positive sera were serially diluted in CSF from an uninfected patient. NGS repeatedly detected HIV and HBV sequences present at concentrations from 105 to 102 and from 105 to 10 viral copies/reaction, respectively. However, when the same protocols were applied to RT-PCR/PCR positive CSF samples from 6 patients with enteroviral encephalitis (median viral load 47 copies/ml) and 15 patients with HSV, CMV or VZV encephalitis (median viral load 148 copies/ml), only 7 (28.6%) were identified as positive. In conclusions, while NGS has the advantage of being able to identify a wide range of potential pathogens it seems to be less sensitive compared to the standard amplification-based assays in the diagnosis of encephalitis, where low viral loads are common.

Purpose Determining the role of DYNC2H1 variants in nonsyndromic inherited retinal disease (IRD). Methods Genome and exome sequencing were performed for five unrelated cases of IRD with no identified variant. In vitro assays were developed to validate the variants identified (fibroblast assay, induced pluripotent stem cell [iPSC] derived retinal organoids, and a dynein motility assay). Results Four novel DYNC2H1 variants (V1, g.103327020_103327021dup; V2, g.103055779A>T; V3, g.103112272C>G; V4, g.103070104A>C) and one previously reported variant (V5, g.103339363T>G) were identified. In proband 1 (V1/V2), V1 was predicted to introduce a premature termination codon (PTC), whereas V2 disrupted the exon 41 splice donor site causing incomplete skipping of exon 41. V1 and V2 impaired dynein-2 motility in vitro and perturbed IFT88 distribution within cilia. V3, homozygous in probands 2–4, is predicted to cause a PTC in a retina-predominant transcript. Analysis of retinal organoids showed that this new transcript expression increased with organoid differentiation. V4, a novel missense variant, was in trans with V5, previously associated with Jeune asphyxiating thoracic dystrophy (JATD). Conclusion The DYNC2H1 variants discussed herein were either hypomorphic or affecting a retina-predominant transcript and caused nonsyndromic IRD. Dynein variants, specifically DYNC2H1 variants are reported as a cause of non syndromic IRD.

Biallelic mutations in the AP4B1 gene, encoding adaptor-related protein complex 4 beta-1 subunit, have been recognized as an important cause of a group of conditions leading to adaptor-related protein complex 4 (AP4)-associated hereditary spastic paraplegia (SPG47). We describe a homozygous, known variant c.1160_1161delCA (p.Thr387fs) that was found in the largest ever group of patients coming from four families. The patients exhibited early hypotonia progressing to spastic paraplegia, microcephaly, epilepsy, and central nervous system (CNS) defects and global developmental delay that are consistent with the nature of SPG47. Our findings expand phenotypic spectrum of SPG47 to include polymorphic seizures, mild/moderate intellectual disability, and intracerebral cysts as well as point to founder mutation in AP4 deficiency disorders in apparently non-consanguineous Polish families without shared ancestry. Electronic supplementary material The online version of this article (10.1007/s13353-020-00552-w) contains supplementary material, which is available to authorized users.

Alveolar capillary dysplasia with misalignment of pulmonary veins (ACDMPV) is a lethal lung developmental disorder caused by the arrest of fetal lung formation, resulting in neonatal death due to acute respiratory failure and pulmonary arterial hypertension. Heterozygous single-nucleotide variants or copy-number variant (CNV) deletions involving the FOXF1 gene and/or its lung-specific enhancer are found in the vast majority of ACDMPV patients. ACDMPV is often accompanied by extrapulmonary malformations, including the gastrointestinal, cardiac, or genitourinary systems. Thus far, most of the described ACDMPV patients have been diagnosed post mortem, based on histologic evaluation of the lung tissue and/or genetic testing. Here, we report a case of a prenatally detected de novo CNV deletion (~0.74 Mb) involving the FOXF1 gene in a fetus with ACDMPV and hydronephrosis. Since ACDMPV is challenging to detect by ultrasound examination, the more widespread implementation of prenatal genetic testing can facilitate early diagnosis, improve appropriate genetic counselling, and further management.

Genetic mosaicism caused by postzygotic mutations is of a great interest due to its role in human disease. Monozygotic twins arising from a single zygote are considered as genetically identical, and any differences likely to be caused by postzygotic events. Thus, phenotypically discordant monozygotic twins offer a unique opportunity to study genotype-phenotype correlation. Here, we present a three-generation family starting from a pair of monozygotic twins discordant for metachondromatosis due to postzygotic p.(Gln175His) variant in the PTPN11 gene. Both phenotypically discordant monozygotic twins harbor p.(Gln175His), however significant differences in mosaic ratio is observed not only between twins, but also within different tissue types within one individual. Phenotypic manifestation of p.(Gln175His) in examined family clearly depends on allele variant fraction (VAF). Individuals harboring constitutional mutation (VAF 50%) present typical metachondromatosis. Milder phenotype is observed in twin harboring high-level mosaicism in the tissue of ectodermal origin (VAF 45%), but not in a blood (VAF 5%). Finally, her twin sister harboring low-level mosaicism in blood (VAF 2%) and nonblood (VAF 12%) tissues is phenotypically normal. Our results provide insights into biological role of mosaicism in disease and further support the usefulness of nonblood tissues as an optimal source of DNA for the identification of postzygotic mutations in phenotypically discordant monozygotic twins.

The MYCN oncogene encodes a transcription factor belonging to the MYC family. It is primarily expressed in normal developing embryos and is thought to be critical in brain and other neural development. Loss-of-function variants resulting in haploinsufficiency of MYCN, which encodes a protein with a basic helix–loop–helix domain causes Feingold syndrome (OMIM 164280, ORPHA 391641). We present an occurrence of esophageal atresia (EA) with tracheoesophageal fistula in siblings from a three-generation family affected by variable expressivity of MYCN mutation p.(Ser90GlnfsTer176) as a diagnostic effect of searching the cause of familial esophageal atresia using NGS-based whole-exome sequencing (WES). All of our affected patients showed microcephaly and toe syndactyly, which were frequently reported in the literature. Just one patient exhibited clinodactyly. None of the patients exhibited brachymesophalangy or hypoplastic thumbs. The latest report noted that patients with EA and Feingold syndrome were also those with the more complex and severe phenotype. However, following a thorough review of the present literature, the same association was not found, which is also confirmed by the case we described. The variable phenotypic expression of the patients we described and the data from the literature guide a careful differential diagnosis of Feingold syndrome even in cases of poorly expressed and non-specific symptoms.

The technological progress of massively parallel sequencing (MPS) has triggered a remarkable development in the research on postzygotic mutations. Although the overwhelming majority of studies in the field focus on oncogenesis, non-neoplastic diseases are attracting more and more attention. The aim of this review was to summarize some of the most recent findings in the field of somatic mosaicism in diseases other than neoplastic events. We discuss the abundance and role of postzygotic mutations, with a special emphasis on disorders which occur only in a mosaic form (obligatory mosaic diseases; OMDs). Based on the list of OMDs compiled from the published literature and three databases (OMIM, Orphanet and MosaicBase), we demonstrate the prevalence of cancer-related genes across OMDs and suggest other sources to further explore OMDs and OMD-related genes. Additionally, we comment on some practical aspects related to mosaic diseases, such as approaches to tissue sampling, the MPS coverage required to detect variants at a very low frequency, as well as on bioinformatic and molecular tools dedicated to detect somatic mutations in MPS data.

Background The most common cause of Unexplained Sudden Cardiac Arrest (USCA) are hereditary primary arrhythmic syndromes and subclinical forms of cardiomyopathies. Both of them may be difficult to diagnose. Objective The aim of this study was to re-examine the role of genetic testing in patients after USCA during follow-up. Methods In the years 2014–2017 we studied 44 unrelated patients (pts) (23 men (53%), mean age 36 years) after USCA. All pts underwent cardiac evaluation including ECG, Holter, echo, coronary angiography, stress exercise test and, if necessary cardiac MRI and provocative drug testing. Standard diagnostic criteria were used according to currently available ESC guidelines. We performed next generation sequencing with panel covered coding regions of >4800 genes (26pts), 194 genes (5pts) and whole exome sequencing >2ehab724.3204 genes (5pts). Variants of frequency no greater than 0,001 in existing variants' databases and classified as damaging by at least 3 of applied software algorithms were assessed for pathogenicity according to ACMG standards. The enrolled patients were followed up. During the follow up, the classification of rare variants according to ACMG standards was repeated. Results Based on applicable standards and the clinical data collected, clinical diagnosis was made in 17 (39%) probands (Long QT Syndrome 21%, Brugada Syndrome 7%, Short QT Syndrome 7%, Early Repolarization Syndrome and Catecholaminergic Polymorphic Ventricular Tachycardia 2%, both). Genetic tests were performed in 36 pts. We identified 27 rare variants in 22 pts, in genes associated with inherited arrhythmia or cardiomyopathies, of these 23 rare variants were identified in years 2014–2017. The first classification was in 2017, then only 2 variants (in FLNC) were considered pathogenic and the remaining 21 were classified as Variants of Unknown Significance (VUS). During the years 2019–2021, 23 earlier identified rare variants were reclassified according to The American College of Medical Genetics and Genomics (ACMG) standards, of these 5 VUS became pathogenic/likely pathogenic variants. In addition, we performed genetic tests in next 5 pts – we identified 4 rare variants – 3 pathogenic and 1 VUS. Detection of certain hereditary background of SCA increased from 6,5% in years 2014–2017, to 25% in years 2019–2021. The median follow-up period was 2366 days (interquartile range 1785–2903 days). 17/44 (39%) pts had adequate discharge of ICD. Two pts were observed with reduction of left ventricular contractility and the development of the initial stages of dilated cardiomyopathy. Conclusion This study shows clinical utility of extensive clinical assessment and follow-up of patient after USCA. Routine genetic testing by next generation sequencing in the patients can help in diagnosis and re-evaluation of rare variants should be made during the follow-up. Funding Acknowledgement Type of funding sources: Public Institution(s). Main funding source(s): grant of National Institute of Cardiology, Warsaw, Poland

Hypopharyngeal cancer represents one of worst types of head and neck tumors with only few studies focusing on the genomic profile of this type of cancer. Using targeted next-generation sequencing we analyzed 48 HPV-negative tumor samples including 23 originating from hypopharynx, and 25 from larynx. Among genes previously described as significantly mutated, TP53, FAT1, NOTCH1, KMT2C and CDKN2A were found to be most frequently mutated. We also found that more than three-fourths of our patients harbored candidate actionable or prognostic alterations in genes belonging to RTK/ERK/PI3K, cell-cycle and DNA-damage repair pathways. Using previously published data we compared 67 hypopharyngeal cancers to 595 head and neck cancers from other sites and found no prominent differences in mutational frequency except for CASP8 and HRAS genes. Since we observed relatively frequent mutations of KTM2C (MLL3) in our dataset, we analyzed their role in vitro by generating KMT2C-mutant hypopharyngeal cancer cell line FaDu with CRISPR-Cas9. We demonstrate that KMT2C loss-of-function results in increased colony formation and proliferation, in concordance with its previously published results. In summary, our results show that mutational profile of hypopharyngeal cancers might be similar to the one observed for other head and neck cancers with respect to minor differences and includes multiple candidate actionable and prognostic genetic alterations. We also demonstrate for the first time that KMT2C gene may play a role of tumor suppressor in head and neck cancer, which opens new possibilities in the search for new targeted treatment approaches.

Germline variants in tumor necrosis factor receptor-associated factor 7 (TRAF7) gene have recently been described in about 50 patients with developmental delay and cardiac, facial, and digital anomalies (CAFDADD). We aimed to depict further the clinical and genetic spectrum associated with TRAF7 germline variants in two additional patients, broaden the mutational spectrum, and support the characteristic clinical variety to facilitate the diagnostics of the syndrome among physician involved in the evaluation of patients with developmental delay/congenital malformations.