Frameshift Deletion Mutation Research Articles

Genetic analysis of a family with hereditary hemorrhagic telangiectasia caused by a novel frameshift deletion mutation of the endoglin (ENG) gene

Genetic analysis of a family with hereditary hemorrhagic telangiectasia caused by a novel frameshift deletion mutation of the endoglin (ENG) gene

Biological characterization of lipoic acid- and heme-dependent Escherichia coli small colony variants isolated from sheep in Xinjiang, China.

Escherichia coli (E. coli) small colony variants (SCVs) have garnered attention due to their heightened antibiotic resistance and enhanced cell retention, posing significant risks to public health and food safety. However, understanding of SCVs derived from sheep remains limited. This study aimed to detect the biological characterization of sheep-derived E. coli SCVs and investigate the factors contributing to SCV development with preliminary genomic data. In this study, a lipoic acid-dependent SCV (LA-SCV) and a wild-type (WT) strain were isolated from sheep bile. Then, a heme-dependent SCV (HD-SCV) was induced from WT using amikacin. Initially, we examined factors contributing to SCV formation via comparative genomics. Subsequent comparisons between WT and two SCV strains encompassed antibiotic resistance, hemolytic activity, biofilm formation, motility, and metabolism. Genomic analyses identified a frameshift deletion mutation in the lipA gene in LA-SCV and a stopgain mutation in the hemG gene in HD-SCV, hypothesized as potential triggers for lipoic acid- and heme-dependent SCV development, respectively. Physiological, biochemical, and cultural traits exhibited notable differences between WT and SCVs, including increased antibiotic resistance, hemolytic activity, and biofilm formation, but alongside non-fermentative acetate utilization, slow growth, reduced intracellular ATP, and decreased motility (P < 0.01). The energy and amino acid metabolism were suppressed during the logarithmic phase in LA-SCV, while both logarithmic and stable phases in HD-SCV. These alterations in biological characteristics present significant challenges in managing E. coli pathogenicity and antibiotic resistance.

Clinical Characteristics and Prognosis of Myelodysplastic Syndromes Patients with RUNX1 Gene Mutation

To investigate the clinical characteristics and survival analysis of myelodysplastic syndromes (MDS) with RUNX1 gene mutation. Clinical data of 177 newly diagnosed MDS patients admitted to the Department of Hematology, the Second Affiliated Hospital of Air Force Military Medical University from October 1, 2015 to October 31, 2022 were retrospectively analyzed. Gene mutation detection was performed by second-generation sequencing technology, and clinical characteristics and prognosis of patients with RUNX1 gene mutation were analyzed. A total of 30 cases (16.95%) of RUNX1 gene mutations were detected, including 15 missense mutations (50.0%), 9 frameshift deletion mutations (30.0%), 4 splice site mutations (13.3%), 1 insertion mutation (3.3%), and 1 nonsense mutation (3.3%). Patients with RUNX1 mutations had a median age of 68.5 years at diagnosis (range: 62.25-78.50 years old). There were no significantly differences between RUNX1 mutations and wild type patients in age distribution, gender, peripheral blood white blood cell count, hemoglobin level, bone marrow and peripheral blood blasts ratio, IPSS-R cytogenetics, IPSS-R stage, etc. (P >0.05). However, there were statistically significant differences in platelet count and whether complicated karyotype. Compared with patients without RUNX1 gene mutation, patients with RUNX1 gene mutation had lower platelet count (P =0.018), and were less likely to have complicatedkaryotype at initial diagnosis (P =0.01). Cox proportional hazards model analysis showed that when other covariates remained unchanged, the higher the platelet count, the better the survival of patients (HR=0.995, 95%CI : 0.990-0.999, P =0.036); In the IPSS-M prognostic stratification, keeping other covariates unchanged, the risk of progression or death of myelodysplastic syndrome was significantly lower in the medium to high-risk and low-risk groups compared with the high-risk group (HR=0.149, 95%CI : 0.031-0.721, P =0.018; HR=0.026, 95%CI : 0.003-0.234, P =0.001). Survival analysis showed that MDS patients with RUNX1 gene mutation had worse overall survival time (P < 0.001). Patients with RUNX1 mutation had worse OS than non-mutation patients in the early WHO group. RUNX1 mutation and IPSS-M risk stratification mean OS and mean LFS were worse in low-risk patients than in non-mutated patients. RUNX1 gene mutation is an adverse prognostic factor in MDS patients, especially in the IPSS-M prognosis stratification group of low-risk, medium-low risk, medium-high risk and WHO classification of early patients.

Unravelling the genomic origins of lumpy skin disease virus in recent outbreaks.

Lumpy skin disease virus (LSDV) belongs to the genus Capripoxvirus and family Poxviridae. LSDV was endemic in most of Africa, the Middle East and Turkey, but since 2015, several outbreaks have been reported in other countries. In this study, we used whole genome sequencing approach to investigate the origin of the outbreak and understand the genomic landscape of the virus. Our study showed that the LSDV strain of 2022 outbreak exhibited many genetic variations compared to the Reference Neethling strain sequence and the previous field strains. A total of 1819 variations were found in 22 genome sequences, which includes 399 extragenic mutations, 153 insertion frameshift mutations, 234 deletion frameshift mutations, 271 Single nucleotide polymorphisms (SNPs) and 762 silent SNPs. Thirty-eight genes have more than 2 variations per gene, and these genes belong to viral-core proteins, viral binding proteins, replication, and RNA polymerase proteins. We highlight the importance of several SNPs in various genes, which may play an essential role in the pathogenesis of LSDV. Phylogenetic analysis performed on all whole genome sequences of LSDV showed two types of variants in India. One group of the variant with fewer mutations was found to lie closer to the LSDV 2019 strain from Ranchi while the other group clustered with previous Russian outbreaks from 2015. Our study highlights the importance of genomic characterization of viral outbreaks to not only monitor the frequency of mutations but also address its role in pathogenesis of LSDV as the outbreak continues.

THU149 A Novel Frameshift Mutation (p.H485fs) Of The Ldl Receptor Gene

Abstract Disclosure: S. Chang: None. E. Yang: None. C. Kim: None. Familial hypercholesterolemia (FH) is characterized by significantly elevated low-density lipoprotein cholesterol (LDL-C) that leads to atherosclerotic plaque deposition in the coronary arteries and proximal aorta at an early age and increases the risk of premature cardiovascular events such as angina and myocardial infarction. It is an autosomal dominant inherited disease due to mutations in either the low-density lipoprotein receptor (LDL-R), the apolipoprotein B or the proprotein convertase subtilisin/kexin type 9 genes. In this study, we report a novel mutation in LDL receptor gene in a Korean family. A 10 year-old boy was referred to our hospital for hypercholesterolemia (530 mg/dl). On family history, His father and uncle have been treated for hypercholesterolemia and his grandfather died of coronary artery disease. Because of persisted hypercholesterolemia despite statin treatment for 18 months and his family history, we performed LDL-R gene study using polymerase chain reaction (PCR) sequencing. Direct sequencing of the 18 exons and exon-intron boundaries of LDL-R gene revealed deletions of C and A of exon 10 (c.1455_1456del). Study showed a novel heterozygous frameshift-deletion mutation (p.His485Glnfs*50) (p.H485fs). We performed PCR sequencing to detect same mutation on his family. Father and two siblings of the patient have same mutation (p.His485Glnfs*50) (p.H485fs) on study. Now we report a novel frameshift mutation (p.H485fs) located in exon 10 of LDL receptor gene that causes familial hypercholesterolemia in a Korean family. Presentation: Thursday, June 15, 2023

Nasopharyngeal carcinoma patient-derived xenograft mouse models reveal potential drugs targeting cell cycle, mTOR, and autophagy pathways

BackgroundNasopharyngeal carcinoma (NPC) is associated with Epstein–Barr virus (EBV) infection. To test preclinical NPC drugs, we established two patient-derived xenograft (PDX) mouse models, EBV-positive PDX-B13 and EBV-negative PDX-Li41, for drug screening. MethodsBased on next generation sequencing (NGS) studies, PDX-B13 had CCND1 copy number (CN) gain but CDKN2A CN loss, whereas PDX-Li41 had CDKN2A and RB1 CN loss, TSC1 (negative regulator of mTOR) frameshift deletion mutation, and increased activation of mTOR, a serine/threonine kinase that governs metabolism, autophagy, and apoptosis. Increased mTOR was also associated with poor NPC prognosis. ResultsEverolimus, an mTOR inhibitor, suppressed tumor growth in the two PDX NPC models and had an additive antitumor effect with palbociclib, a CDK4/6 inhibitor. PDX tumors treated with various drugs or untreated were subjected to RNA sequencing, transcriptome profile analysis, and selective Western blotting to understand the interactions between these drugs and gene expression profiles. Palbociclib also suppressed EB viral nuclear antigen (EBNA1) expression in PDX-B13. Everolimus together with autophagy inhibitor, hydroxychloroquine, had additive anti-tumor effect on PDX-B13 tumor. Immunohistochemistry revealed that high mTOR levels were correlated with poor overall survival in patients with metastatic NPC (N = 90). ConclusionsHigh mTOR levels are a poor prognostic factor in NPC, and cell cycle, mTOR and autophagy pathways may serve as therapeutic targets in NPC. In addition, PDX models can be used for efficiently testing potential NPC drugs.

Three cases of colon cancer in four generations of the Saudi family, caused by endogamous germline mutations.

Various research pieces of evidence have been published in recent years, establishing the increasing prevalence of early colon cancer among young people. In this background, the current study aimed to analyze the reasons behind colon cancer recurrence among endogamous consanguineous cases in four generations of a single Saud family. For this study, the authors conducted the whole-exome sequencing analysis to screen for germline mutations in DNA samples from consanguineous cases within the family. After collecting the colon samples, it was analyzed histologically and immunohistochemically with the help of Breast Cancer antibodies (BRCA2 and 1 correspondingly) and H&M staining (hematoxylin and eosin). For this study, 26 at-risk consanguineous cases were considered. Three cases were diagnosed with malignant colon cancer, two with breast cancer, and 17 with germline mutations, yet remain unaffected by cancerous tumors. The rest, four consanguineous cases, are healthy and non-carriers of the mutations. However, as per the exome analysis outcomes, 15 cases inherited germline mutations in nine genes. Nine substitution mutations were present in six of the nine inherited genes in these inherited germline mutations. Furthermore, it also presented six insertion and deletion frameshift mutations in five of nine inherited genes. The immunohistochemical staining process achieved positive staining outcomes for BRCA1 and 2. Therefore, germline mutations inherited from the nine genes of endogamous consanguineous cases of mutation carriers remain the primary reason behind colon cancer recurrence in the same family.

Identification of novel homozygous missense and deletion mutations manifesting oligospermia infertility in Kashmiri population.

Human male infertility has a lot of known molecular components that have an accurate diagnosis, such as Y chromosome deletion and monogenic causes. Only 4% of all infertile males are diagnosed with genetic causes, while 60-70% of infertile men remain without an accurate diagnosis and are classified as unexplained. Oligospermia is a major cause of human male infertility. Its etiology and pathogenesis are linked to genetic abnormalities. The majority of genetic causes related to human male infertility remain unclear. Generally, we found a significant association between the specific type of disease and gender (p= 0.003), and the regression value (R2 ) for this association was 0.75. Association of the type of disease with body mass index was not significant (p= 0.34). There was no statistically significant difference (p= 0.40) among disease types with patients occupations. All explored mutations are listed for primary and secondary infertility in relation to the oligospermia condition. p.Arg286X is the outcome of a mismatch mutation in which the nucleotide change resulted in the substitution of Arg (arginine) amino acid with X (any amino acid) at position 286 in the Hyal3 gene of primary infertile patients having oligospermia. In primary infertile patients with the p.Arg286X mutation, a frameshift deletion mutation was also found just after the 25 nucleotide sequences of the Hyal3 genes of the second mutated exon. This deletion mutation was only detected in patients with primary infertility and was not found in people with secondary infertility or healthy controls. The other mutations in secondary infertile patients with oligospermia were: p.Lys168Ser, replacement of lysine (Lys) with serine (Ser) at position 168; p.Lys168The, replacement of lysine (Lys) with threonine (The) at position 168; p.His113X, substitution of histidine (His) with an unknown amino acid (X) at position 113; p.Pro162X, substitution of proline (Pro) with an unknown amino acid (X) at position 162; and p.Phe157X, phenylalanine (Phe) substitution with an unknown amino acid (X) at position 157. This study clarifies the site of novel mismatch and frameshift deletion mutations in the Hyal3 gene in primary infertile oligospermia patients.

A Novel Pair of Compound Heterozygous Mutation of EYS in a Han Chinese Family with Retinitis Pigmentosa.

Background: Retinitis pigmentosa (RP) is a complex inherited and progressive degenerative retinal disease. The eyes shut homolog (EYS) is frequently associated with RP is surprisingly high. Exploring the function of EYS is quite difficult due to the unique gene size and species specificity. Gene therapy may provide a breakthrough to treat this disease. Therefore, exploring and clarifying pathogenic mutations of EYS-associated RP has important guiding significance for clinical treatment. Methods: Clinical and molecular genetic data for EYS-associated RP were retrospectively analyzed. Sanger sequencing was applied to identify novel mutations in these patients. Candidate pathogenic variants were subsequently evaluated using bioinformatic tools. Results: A novel pair of compound heterozygous mutations was identified: a novel stop-gain mutation c.2439C>A (p.C813fsX) and a frameshift deletion mutation c.6714delT (p. P2238fsX) of the EYS gene in the RP family. Both of these mutations were rare or absent in the 1000 Genomes Project, dbSNP, and Genome Aggregation Database (gnomAD). These two mutations would result in a lack of multiple functionally important epidermal growth factor-like and Laminin G-like coding regions in EYS. Conclusions: A novel compound heterozygote of the EYS gene in a Chinese family with an autosomal inheritance pattern of RP was identified. Identifying more pathogenic mutations and expanding the mutation spectrum of the EYS gene will contribute to a more comprehensive understanding of the molecular pathogenesis of RP disease that could be gained in the future. It also could provide an important basis for the diagnosis, clinical management, and genetic counseling of the disease.

Genetic mutations in smoking-associated prostate cancer.

Tobacco smoking is known to cause cancers potentially predisposed by genetic risks. We compared the frequency of gene mutations using a next generation sequencing database of smokers and nonsmokers with prostate cancer (PCa) to identify subsets of patients with potential genetic risks. Data from the American Association for Cancer Research Project Genomics Evidence Neoplasia Information Exchange (GENIE) registry was analyzed. The GENIE registry contains clinically annotated sequenced tumor samples. We included 1832 men with PCa in our cohort, categorized as smokers and nonsmokers, and compared the frequency of mutations (point mutations, copy number variations, and structural variants) of 47 genes with more than 5% mutation rate between the two categories and correlated with overall survival using logistic regression analysis. Overall, 1007 (55%) patients were nonsmokers, and 825 (45%) were smokers. The mutation frequency was significantly higher in smokers compared to nonsmokers, 47.6% and 41.3%, respectively (p = 0.02). The median tumor mutational burden was also significantly higher in the samples from smokers (3.59 mut/MB) compared to nonsmokers (1.87 mut/MB) (p < 0.001). Patients with a smoking history had a significantly higher frequency of PREX2, PTEN, AGO2, KMT2C, and a lower frequency of adenomatous polyposis coli (APC) and KMT2A mutations than compared to nonsmokers. The overall mortality rate (28.5% vs. 22.8%) was significantly higher among smokers (p = 0.006). On a multivariate logistic regression analysis, the presence of metastatic disease at the time of diagnosis (OR: 2.26, 95% CI: 1.78-2.89, p < 0.001), smoking history (OR: 1.32, 95% CI: 1.05-1.65, p = 0.02), and higher frequency of PTEN somatic gene mutation (OR: 1.89, 95% CI: 1.46-2.45, p < 0.001) were independent predictors of increased overall mortality among patients with PCa. Patients with PTEN mutation had poorer overall survival compared to men without PTEN mutations: 96.00 (95% CI: 65.36-113.98) and 120.00 (95% CI: 115.05-160.00) months, respectively (p < 0.001) irrespective of smoking history although the G129R PTEN mutation was characteristically detected in smokers. PCa patients with a tobacco smoking history demonstrated a significantly higher frequency of somatic genetic mutations. Whereas mutations of PREX2, KMT2C, AGO2, and PTEN genes were higher in smokers, the APC and KMT2A mutations were higher in nonsmokers. The PTEN somatic gene mutation was associated with increased overall mortality among patients with PCa irrespective of smoking history. We found that G129R PTEN mutation known to reduce the PTEN phosphatase activity and K267Rfs*9 a frameshift deletion mutation in the C2 domain of PTEN associated with membrane binding exclusively detected in smokers and nonsmokers, respectively. These findings may be used to further our understanding of PCa associated with smoking.

A frameshift-deletion mutation in Reelin causes cerebellar hypoplasia in White Swiss Shepherd dogs.

Cerebellar hypoplasia is a heterogeneous neurological condition in which the cerebellum is smaller than usual or not completely developed. The condition can have genetic origins, with Mendelian-effect mutations described in several mammalian species. Here, we describe a genetic investigation of cerebellar hypoplasia in White Swiss Shepherd dogs, where two affected puppies were identified from a litter with a recent common ancestor on both sides of their pedigree. Whole genome sequencing was conducted for 10 dogs in this family, and filtering of these data based on a recessive transmission hypothesis highlighted five protein-altering candidate variants - including a frameshift-deletion of the Reelin (RELN) gene (p.Val947*). Given the status of RELN as a gene responsible for cerebellar hypoplasia in humans, sheep and mice, these data strongly suggest the loss-of-function variant as underlying these effects. This variant has not been found in other dog breeds nor in a cohort of European White Swiss Shepherds, suggesting a recent mutation event. This finding will support the genotyping of a more diverse sample of dogs, and should aid future management of the harmful allele through optimised mating schemes.

Identification of DSPP novel variants and phenotype analysis in dentinogenesis dysplasia Shields type II patients.

To investigate the genetic causes and teeth characteristics of dentin dysplasia Shields type II(DD-II) in three Chinese families. Data from three Chinese families affected with DD-II were collected. Whole-exome sequencing (WES) and whole-genome sequencing (WGS) were conducted to screen for variations, and Sanger sequencing was used to verify mutation sites. The physical and chemical characteristics of the affected teeth including tooth structure, hardness, mineral content, and ultrastructure were investigated. A novel frameshift deletion mutation c.1871_1874del(p.Ser624fs) in DSPP was found in families A and B, while no pathogenic mutation was found in family C. The affected teeth's pulp cavities were obliterated, and the root canals were smaller than normal teeth and irregularly distributed comprising a network. The patients' teeth also had reduced dentin hardness and highly irregular dentinal tubules. The Mg content of the teeth was significantly lower than that of the controls, but the Na content was obviously higher than that of the controls. A novel frameshift deletion mutation, c.1871_1874del (p.Ser624fs), in the DPP region of the DSPP gene causes DD-II. The DD-II teeth demonstrated compromised mechanical properties and changed ultrastructure, suggesting an impaired function of DPP. Our findings expand the mutational spectrum of the DSPP gene and strengthen the understanding of clinical phenotypes related to the frameshift deletion in the DPP region of the DSPP gene. A DSPP mutation can alter the characteristics of the affected teeth, including tooth structure, hardness, mineral content, and ultrastructure.

De novo familial adenomatous polyposis associated thyroid cancer with a c.2929delG frameshift deletion mutation in APC: a case report and literature review

BackgroundGermline mutations in the APC gene located on chromosome 5q 21–22 can lead to familial adenomatous polyposis (FAP) and the development of colorectal cancer (CRC) if left untreated. As a rare extracolonic manifestation, thyroid cancer is diagnosed in about 2.6% of FAP patients. The genotype–phenotype correlation in FAP patients with thyroid cancer remains unclear.Case presentationWe present a 20-year-old female of FAP with thyroid cancer as the initial manifestation. The patient was asymptomatic and developed colon cancer liver metastases 2 years after the diagnosis of thyroid cancer. The patient underwent multiple surgical treatments in several organs, and regular colonoscopy with endoscopic polypectomy was performed. Genetic testing demonstrated the c.2929delG (p.Gly977Valfs*3) variant in exon 15 of the APC gene. This represents a previously undescribed APC mutation. This mutation causes loss of multiple structures on the APC gene including the 20-amino acid repeats, the EB1 binding domain, and the HDLG binding site, which may be pathogenic through β-catenin accumulation, cell cycle microtubule dysregulation, and tumor suppressor inactivation.ConclusionsWe report a de novo FAP case with thyroid cancer presenting atypically aggressive features harboring a novel APC mutation and review APC germline mutations in patients with FAP-associated thyroid cancer.

Impact of Four Ovine TMEM154 Haplotypes on Ewes during Multiyear Lentivirus Exposure.

Polypeptide variation encoded by the ovine transmembrane protein 154 gene (TMEM154) is associated with susceptibility to ovine lentivirus, the causative agent of Ovine Progressive Pneumonia (OPP) and Visna/Maedi. Our aim was to compare the four most prevalent TMEM154 haplotypes on the incidence of infection and ewe productivity during natural multiyear virus exposure. Prospective cohort studies were designed to test gene action and estimate effects of TMEM154 haplotypes encoding distinctive variant residues: K35 (“1”), I70 (“2”), ancestral (“3”), and A4del/M44 (“4”). Exposure consisted of co-mingling infected ewes at a rate greater than 30% with serological status evaluated every four months. For ewes with one or two copies of the highly susceptible haplotypes “2” and ”3”, the infection prevalence steadily increased to nearly 100% at 55 months. Haplotypes “2” and “3” were equally susceptible and dominant to haplotype “1”. A difference was not detected (p < 0.53) in the magnitude of effect with haplotype combinations of “1” and ”4”. The ewe infection prevalence with “1,1”; “1,4”; and “4,4” was 10% to 40% at 55 months. The latter suggested that two copies of the K35 amino acid substitution (“1”) were as effective as a homozygous TMEM154 “knockout” with the frame-shift deletion mutation (“4”) in reducing infection susceptibility. When considering ewe reproductive performance, a difference was not detected when comparing haplotypes “2”, and “3” to each other, or “1” and “4” to each other. Our study indicated that ewes with two copies of the severely truncated versions of TMEM154 (“4,4”) had normal lamb productivity. Without complete understanding of the natural function of TMEM154 our recommendations to producers interested in using TMEM154 selection to reduce their flock’s genetic predisposition to OPP are encouraged to increase the frequency of TMEM154 haplotype K35 (“1”) since it encodes a full-length protein with minimal difference to the ancestral polypeptide.

A Rare Heterozygous TINF2 Deletional Frameshift Mutation in a Chinese Pedigree With a Spectrum of TBDs Phenotypes.

Telomere biology disorders (TBDs) induced by TINF2 mutations manifest clinically with a spectrum of phenotypes, from silent carriers to a set of overlapping conditions. A rare TINF2 frameshift mutation (c.591delG) encoding a truncated mutant TIN2 protein (p.W198fs) was identified in a 6-years-and-3-month-old Chinese girl with neuroblastoma (NB) by next generation sequencing and confirmed by Sanger sequencing. To explore the possible implications of TINF2 mutations in TBDs development, the TINF2 mutant was transfected into the human embryonic kidney (HEK) 293T cells, and mRNA expression of the shelterin complex components as well as the cellular distribution of mutant TIN2 were examined. The TINF2 mutation was phenotypically associated with short stature in the proband, nail dystrophy and spotted hypopigmentation in her mother, and psoriasis in her older brother. I-TASSER modeling analysis revealed conformational changes of the mutant TIN2 protein and loss of pivotal domains downstream of the 198th amino acid. Additionally, mRNA expression of the shelterin components was downregulated, and TIN2 mutant protein expression was reduced in HEK293T cells transfected with mutant TINF2. Furthermore, instead of being restricted to the nucleus, the mutant TIN2 was identified in both the cytoplasm and the nucleus. The TINF2 gene mutation might impair the function of the shelterin complex and the telomere maintenance mechanisms, both of which are involved in the development of TBDs. TBDs have been associated with increased cancer risk. To the best of our knowledge, this is the first report of NB in patients with TBDs. The relationship between the TINF2 mutation and NB may need to further study.

MEDB-34. A very rare case: medulloblastoma relapse with bone marrow infiltration in a toddler

We report about a female toddler congenitally deaf and diagnosed with a non-metastatic desmoplastic medulloblastoma (SHH activated, TP53-wt, variant in LDB1 gene). No tumor predisposition syndrome was found. After complete tumor resection the patient was treated according to I-HIT-MED-Guidance protocol. Five months later an asymptomatic localised relapse (same histology, PTEN frameshift deletion, TERT mutation, LDB1 mutation) detected by routine MRI was treated by complete resection, craniospinal irradiation and an antiangiogenic regimen adapted from the MEMMAT scheme including fenofibrate, thalidomide, celecoxib, topotecan, temozolomide, bevacizumab and intraventricular cytarabine. Before start of systemic treatment blood cell counts were normal. In the second cycle we had to interrupt chemotherapy due to a leukopenia while continuing the antiangiogenic treatment. In order to avoid relevant bone marrow toxicity chemotherapy doses were reduced. Nevertheless we had to stop the fourth cycle because of a severe pancytopenia. Same time the girl presented with fever, neck and leg pain. A full blood count showed: hemoglobin 6.92 g/dl, leukocytes 640/µl, platelets 8,000/µl. Suspecting an infection supported by the presence of a high CrP value of 230 mg/l the patient was treated with i.v. antibiotics. MRI showed an unspecific retropharyngeal soft tissue augmentation, a pleural effusion and high T2 signals in multiple vertebral bodies but no central tumor relapse. The bone marrow diagnostics revealed a diffuse medulloblastoma cell infiltration with the known PTEN frameshift deletion and LDB1 mutation. The liquor was tumor-cell free. We report on an extremely rare case of an early local relapse of desmoplastic medulloblastoma progressing to a diffuse bone marrow infiltration in a toddler. The girl died due to therapy resistance 9 weeks after bone marrow relapse. It remains unclear whether the fatal course was related to the hereditary deafness syndrome and the molecular alterations of the tumor.

Ultrarare Loss-of-Function Mutations in the Genes Encoding the Ionotropic Glutamate Receptors of Kainate Subtypes Associated with Schizophrenia Disrupt the Interaction with PSD95.

Schizophrenia is a complex mental disorder with a genetic component. The GRIK gene family encodes ionotropic glutamate receptors of the kainate subtype, which are considered candidate genes for schizophrenia. We screened for rare and pathogenic mutations in the protein-coding sequences of the GRIK gene family in 516 unrelated patients with schizophrenia using the ion semiconductor sequencing method. We identified 44 protein-altered variants, and in silico analysis indicated that 36 of these mutations were rare and damaging or pathological based on putative protein function. Notably, we identified four truncating mutations, including two frameshift deletion mutations (GRIK1p.Phe24fs and GRIK1p.Thr882fs) and two nonsense mutations (GRIK2p.Arg300Ter and GRIK4p.Gln342Ter) in four unrelated patients with schizophrenia. They exhibited minor allele frequencies of less than 0.01% and were absent in 1517 healthy controls from Taiwan Biobank. Functional analysis identified these four truncating mutants as loss-of-function (LoF) mutants in HEK-293 cells. We also showed that three mutations (GRIK1p.Phe24fs, GRIK1p.Thr882fs, and GRIK2p.Arg300Ter) weakened the interaction with the PSD95 protein. The results suggest that the GRIK gene family harbors ultrarare LoF mutations in some patients with schizophrenia. The identification of proteins that interact with the kainate receptors will be essential to determine kainate receptor-mediated signaling in the brain.

Deubiquitylase OTUD6B stabilizes the mutated pVHL and suppresses cell migration in clear cell renal cell carcinoma

Von Hippel-Lindau (VHL) is an important tumor suppressor, and its inactivation is a hallmark of inherited VHL disease and most sporadic clear cell renal cell carcinoma (ccRCC). VHL protein (pVHL) with missense point mutations are unstable and degraded by the proteasome because of the disruption of elongin binding. Deubiquitylase ovarian tumor domain-containing 6B (OTUD6B) had been documented to couple pVHL and elongin B to form stable VHL - elonginB - elonginC complex, which protects pVHL from degradation. However, whether OTUD6B governs the stability of pVHL wild type and the missense mutants in ccRCC remains largely elusive. Here, we reported that low OTUD6B level predicted poorer survival in ccRCC patients with VHL missense mutation, but not frameshift deletion and nonsense mutation. OTUD6B is able to interact with wild type pVHL and tumor-derived pVHL missense mutants, except for pVHL I151T, and decrease their ubiquitylation and proteasomal degradation in ccRCC cells. Functionally, we revealed that OTUD6B depletion enhanced cell migration and HIF-2α level in ccRCC cells in a pVHL dependent manner. In addition, OTUD6B depletion reduced the inhibitory effects of ectopic pVHL missense mutants on cell migration and HIF-2α level, except for pVHL I151T. Thus, we speculated that I151 residue might be one of key sites of pVHL binding to OTUD6B. These results suggested that OTUD6B is an important regulator for the stability of pVHL missense mutants, which provides a potential therapeutic strategy for ccRCC with VHL mutations.

First patient in the Iranian Registry with novel DOCK2 gene mutation, presenting with skeletal tuberculosis, and review of literature

BackgroundDedicator of cytokinesis 2 (DOCK2) deficiency is an inborn error of immunity characterized by cellular and humoral immunological abnormalities leading to early-onset infections.Case presentationWe reported a novel case of a 27 months old girl presenting with recurrent pneumonia and a history of skeletal tuberculosis at the age of 19-month-old. Her immunological workup revealed persistent lymphopenia and low CD4 + T cell count along with elevated levels of CD19 +, CD20 +, CD16 +, and CD56 + cells. Furthermore, she had a high level of immunoglobulin (Ig) E and a slightly reduced IgM level with a non-protective antibody titer against diphtheria. The whole-exome sequencing (WES) analysis identified a homozygous frameshift deletion mutation (c.1512delG, p.I505Sfs*28) in exon 16 of the DOCK2 gene. We also conducted electronic searches in PubMed, Web of Science, and Scopus databases and reviewed the articles reporting patients with DOCK2 deficiency. The literature search yielded 14 DOCK2-deficient patients suffering from both cellular and humoral immune defects leading to early-onset infections, particularly human herpesvirus (HHV) infection.ConclusionDOCK2 deficiency should be considered in the context of severe or unusual early-onset infections, especially HHV infections, in a patient with a probable clinical diagnosis of combined immunodeficiency. We also recommended that DOCK2-deficient patients might benefit from T-cell receptor excision circle (TREC) assay as part of the routine newborn screening program.

Comparison of hereditary breast and ovarian cancer syndrome and sporadic ovarian cancer in ovarian cancer BRCA mutations

Objective: To study the difference between BRCA gene mutations in hereditary breast and ovarian cancer syndrome (HBOC) and in sporadic ovarian cancer (SOC). Methods: This study was for exploratory research, the inclusion criteria were 284 patients with ovarian cancer admitted at Shanxi Provincial Cancer Hospital from November 2018 to December 2019, with high-throughput DNA sequencing including the full coding regions and exon-intron link regions of BRCA1 and BRCA2 gene. Pathogenic mutations in the BRCA gene of patients with ovarian cancer were collected and mutation site analysis was performed to compare phenotypic differences in pathogenic mutations between HBOC syndrome and SOC patients. Results: (1) Of the 284 ovarian cancer patients, seventy-seven had BRCA pathogenic mutations with a mutation rate of 27.1% (77/284), with BRCA1 mutation rate of 19.7% (56/284), BRCA2 gene 6.7% (19/284) and BRCA1/2 common mutation rate of 0.7% (2/284). Of the 284 patients with ovarian cancer, the pathogenic mutation rate in the BRCA gene in HBOC syndrome patients was 43.8% (32/73), which were significantly higher than that in SOC patients [21.3% (45/211); χ²=13.905, P<0.01]. Among BRCA1 gene mutation, the mutation rate in HBOC syndrome was higher than that of SOC [87.5% (28/32) vs 62.2% (28/45)], the BRCA2 gene mutation rate in patients with HBOC syndrome was lower than that in SOC patients [6.2% (2/32) vs 37.8% (17/45)], and there were statistically significant differences (all P<0.05). Two of the 77 patients with pathogenic mutations in the BRCA gene were multisite mutations, including one simultaneous two site mutation, one simultaneous three site mutation. There were 80 mutation sites with frameshift deletion mutations (55.0%, 44/80) and nonsense mutations (31.2%, 25/80). (2) Of the 73 patients with HBOC syndrome, 32 cases had pathogenic mutations in BRCA gene, including 28 cases in BRCA1, mainly in exon 11 and 24 (9 and 7 cases, respectively), and only two cases in BRCA2, both in exon 11; another two had multiple locus mutations. Of the 211 patients with SOC, 45 cases had pathogenic mutants in BRCA gene, including 28 cases in BRCA1, mainly in exon 11 and 24 (15 and 2 cases, respectively), and 17 cases in BRCA2, mainly in exon 11 (11 cases). (3) Thirty-four pathogenic mutation sites in BRCA gene were found newly, twenty of them were located in the BRCA1 gene, including a locus located on the intron 6, 301+1G>A, and the remaining 19 sites were located on the exons, including 283_286delCTTG, 68_69delAG, 132C>T, 514_547+3del37, 742delA, 1126_1129delAATA, 1196delA, 1352_1364del, 1465G>T, 2171delC, 2341G>T, 3359_3363delTTAAT, 4085_4086ins11, 4161_4162delTC, 4165_4166delAG, 4258G>T, 4338_4339del8insAGAA, 4468G>T, and 4783delA; fourteen sites were located in the BRCA2 gene, including a locus located on the intron 7, 631+1G>A, and the remaining 13 sites were located on the exons, including 2648delT, 2914A>T, 2950_2951insG, 4357+1G>A, 5054C>T, 5257A>T, 5291_5292insTC, 5913delT, 3593delA, 6091_6092insA, 6135_6136delTT, 7452delT, 9097_9098insA. A tal of 28 repeat mutations were located in the BRCA1 gene; among them, the site 5470_5477del8 was repeated 6 times, while 3 times in 981_982delAT. Conclusions: Patients with HBOC syndrome have a significantly higher rate of pathogenic mutation in the BRCA gene than that in patients with SOC. BRCA gene pathogenic mutation sites in HBOC syndrome patients occur commonly in exon 11 and 24 of BRCA 1 gene, while SOC patients occur mainly in exon 11 and 24 of BRCA1 gene and exon 11 of BRCA2 gene. The two loci of BRCA1∶5470_5477del8, BRCA1∶981_982delAT may be ancestor mutations in Chinese ovarian cancer patients, and 34 newly discovered pathogenic mutations in the BRCA gene, enriching the BRCA gene mutation spectrum in the Chinese population.