Identification of compound heterozygous deletion of the WWOX gene in WOREE syndrome.

BACKGROUND: Biallelic loss-of-function variants in WWOX cause WWOX-related epileptic encephalopathy (WOREE syndrome), which has been reported in 60 affected individuals to date. In this study, we report on an affected individual with WOREE syndrome who presented with early-onset refractory seizures and global neurodevelopmental delay and died at the age of two and a half years. METHODS: We present clinical and molecular findings in the affected individual, including biallelic pathogenic variants in the WWOX gene. We employed different molecular approaches, such as whole exome sequencing, quantitative real-time polymerase chain reaction (qPCR), and whole-genome sequencing, to identify the genetic variants. The breakpoints were determined through gap PCR and Sanger sequencing. RESULT: Whole exome sequencing revealed homozygous exon 6 deletion in the WWOX gene in the proband. Quantitative real-time PCR confirmed that the parents were heterozygous carriers of exon 6 deletion. However, using whole-genome sequencing, we identified three larger deletions (maternal allele with exon 6-8 deletion and paternal allele with two deletions in proximity one in intron 5 and the other in exon 6) involving the WWOX gene in the proband, with deletion sizes of 13,261 bp, 53,904 bp, and 177,200 bp. The exact breakpoints were confirmed through gap PCR and Sanger sequencing. We found that the proband inherited the discontinuous deletion of intron 5 and exon 6 from the father, and the exons 6-8 deletion from the mother using gap PCR. CONCLUSION: Our findings extend the variant spectrum of WOREE syndrome and support the critical role of the WWOX gene in neural development.

Novel Mutation With Literature Review WW Domain-Containing Oxidoreductase (WWOX) Gene.

Genetic alterations in the WW domain-containing oxidoreductase (WWOX) gene cause autosomal recessive developmental and epileptic encephalopathy, characterized by the onset of refractory seizures in infants, along with severe axial hypotonia and profoundly impaired psychomotor development. It has also been expanded to include metabolism and endocrine systems. Despite its function as a tumor suppressor gene, genetic alterations in WWOX have been found in several metabolic disorders and neural diseases related to brain development. Whole-exome sequencing (WES) was performed on the patient sample. Genomic DNA was fragmented, and the exons of known genes in the human genome, as well as the corresponding exon-intron boundaries,were enriched using Roche KAPA capture technology (KAPA hyperExome Library, WES identifying the homozygous variant c.406A>G in WWOX (OMIM:605131). This variant of WWOX was also observed in the prenatal WES data, indicating that both parents were heterozygous carriers and the detected variant was homozygous. This study highlighted the importance of the human WWOX gene in brain development and the association between WWOX gene mutations and developmental delay. We recommend performing WES as a primary screening before the final diagnosis, particularly in populations with high rates of consanguinity and in clinically challenging cases.

A Phenotypic-Driven Approach for the Diagnosis of WOREE Syndrome.

Background: WOREE syndrome is a rare neurodevelopmental disorder featuring drug-resistant epilepsy and global developmental delay. The disease, caused by biallelic pathogenic variants in the WWOX gene, usually leads to severe disability or death within the first years of life. Clinicians have become more confident with the phenotypic picture of WOREE syndrome, allowing earlier clinical diagnosis. We report a boy with a peculiar clinic-radiological pattern supporting the diagnosis of WOREE syndrome. Methods: DNA was extracted from blood samples of the proband and his parents and subjected to Exome Sequencing (ES). Agarose gel electrophoresis, real-time quantitative PCR (Q-PCR), and array-CGH 180K were also performed. Results: ES detected a pathogenic stop variant (c.790C > T, p.Arg264*) in one allele of WWOX in the proband and his unaffected mother. A 180K array-CGH analysis revealed a 84,828-bp (g.chr16:78,360,803-78,445,630) deletion encompassing exon 6. The Q-PCR product showed that the proband and his father harbored the same deleted fragment, fusing exons 5 and 7 of WWOX. Conclusions: Genetic testing remains crucial in establishing the definitive diagnosis of WOREE syndrome and allows prenatal interventions/parental counseling. However, our findings suggest that targeted Next Generation Sequencing-based testing may occasionally show technical pitfalls, prompting further genetic investigation in selected cases with high clinical suspicion.

Case report of early-onset epileptic encephalopathy caused by compound heterozygous mutation of the WWOX gene / 中华实用儿科临床杂志

Clinical data of a case with early-onset epileptic encephalopathy admitted in the Department of Neuroendocrinology, Jinan Children′s Hospital in April 2020 were retrospectively analyzed.A 1-month-old male patient was hospitalized for convulsion for 4 days.The child had repeated seizures in the form of tonic and tonic-spasm seizures, accompanied by feeding difficulties, slow weight gain, and overall developmental delay.Electroencephalogram showed multifocal discharge, atypical hypsarrhythmia, and brain magnetic resonance imaging showed delayed myelination.The whole exome sequencing showed compound heterozygous mutation of the WWOX gene.Topiramate, Levetiracetam and Valporate were ineffective to this case.Genetic testing should be performed timely in patients with early-onset epileptic encephalopathy and overall developmental delay to make a clear etiology and prognosis, thus guiding prenatal diagnostics and genetic counseling.

A Chinese patient with epilepsy and WWOX compound heterozygous mutations.

Early infantile epileptic encephalopathy type 28 is a refractory epilepsy with early onset, poor prognosis, and hereditary causes. WW domain-containing oxidoreductase (WWOX) gene mutation can result in epileptic encephalopathy, but the mechanism remains unclear. We present the case of a patient with epilepsy and WWOX compound heterozygous mutations. The seizures manifested as tonic-clonic, convulsive and were refractory to drugs. Magnetic resonance imaging showed a widened subarachnoid space and thin corpus callosum. The patient died from asphyxia at the age of one year and 23 days. Peripheral blood was taken from the patient and his parents, and whole-exome sequencing was investigated to determine possible gene mutation. Two compound heterozygous mutations were identified: c.172+1G>C (with no amino acid change) and c.984C>G (amino acid change: p.Tyr328Ter). The pathophysiology of epileptic encephalopathy related to the WWOX gene remains to be determined, and further studies are required to elucidate possible mechanisms.

A novel missense variant in the SDR domain of the WWOX gene leads to complete loss of WWOX protein with early-onset epileptic encephalopathy and severe developmental delay.

The human WWOX (WW domain-containing oxidoreductase) gene, originally known as a tumor suppressor gene, has been shown to be important for brain function and development. In recent years, mutations in WWOX have been associated with a wide phenotypic spectrum of autosomal recessively inherited neurodevelopmental disorders. Whole exome sequencing was completed followed by Sanger sequencing to verify segregation of the identified variants. Functional WWOX analysis was performed in fibroblasts of one patient. Transcription and translation were assessed by quantitative real-time PCR and Western blotting. We report two related patients who presented with early epilepsy refractory to treatment, progressive microcephaly, profound developmental delay, and brain MRI abnormalities. Additionally, one of the patients showed bilateral optic atrophy. Whole exome sequencing revealed homozygosity for a novel missense variant affecting the evolutionary conserved amino acid Gln230 in the catalytic short-chain dehydrogenase/reductase (SDR) domain of WWOX in both girls. Functional studies showed normal levels of WWOX transcripts but absence of WWOX protein. To our knowledge, our patients are the first individuals presenting the more severe end of the phenotypic spectrum of WWOX deficiency, although they were only affected by a single missense variant of WWOX. This could be explained by the functional data indicating an impaired translation or premature degradation of the WWOX protein.

Association of WWOX rs9926344 polymorphism with poor prognosis of hepatocellular carcinoma.

Introduction: The WW domain-containing oxidoreductase (WWOX), widely expressed in human tissues, is considered as a tumor suppressor gene and plays an important role in the incidence and progression of human cancer, HCC included. This study was to investigate the correlation between single nucleotide polymorphisms (SNPs) of the WWOX gene and the prognosis of hepatocellular carcinoma (HCC) patients. Materials and Methods: After a total of 152 HCC patients were recruited, 8 cases with tumor recurrence within 2-years after operation and 8 cases without recurrence were selected randomly for SNP genotyping and screening using Affymetrix Array 6.0. And then we confirmed candidate SNPs in the remaining 136 patients by time-of-flight mass spectrometry (TOF-MS). Results: In total, 32 SNPs were screened and identified as candidate SNPs with one SNP in particular, (rs9926344), being further verified to be valuable. We found that AA+AG genotype and A allele of WWOX rs9926344 were significantly associated with recurrent risk of HCC (p=0.002 and p=0.001, respectively). The Kaplan-Meier curve showed that patients carrying rs9926344 AA +AG genotype had poor RFS (P=0.004) and OS (P=0.005) compared to those carrying GG genotypes. The multivariate COX regression analysis showed that the AA+AG genotype were an independent prognostic factor for tumor recurrence (HR 1.787, 95% CI 1.042-3.064, P=0.035). Furthermore, IHC analysis showed that the WWOX protein down-regulation is more frequent in patients with AG genotype compared to those with GG genotype (P=0.023). Conclusion: Our findings indicate that WWOX rs9926344 polymorphism is positively correlated with tumor recurrence and can be used as an independent prognostic marker for HCC patients after operation.

Correlation between osteosarcoma and the expression of WWOX and p53.

The objective of this study was to analyze the effect of the expression of WWOX and p53 on the growth of MG-63 osteosarcoma cells and to explore the correlation between osteosarcoma and the expression of WWOX and p53. WWOX and p53-overexpressing MG-63 osteosarcoma cell lines were established by transfection and named the MW and MP cell lines, respectively. Untransfected MG-63 cells (blank control) were used as control. Quantitative polymerase chain reaction (qPCR) and western blot analysis were used to detect the expression of WWOX and wild-type p53 mRNA and protein, respectively. The effects of WWOX and p53 (wild-type) on the activity of MG-63 cells were determined by MTT assay and flow cytometry. The expression of mutant p53 protein in 65 cases of osteosarcoma was detected by immunohistochemistry to analyze the correlation between p53 and the development of osteosarcoma. qPCR showed that WWOX and p53 mRNA was overexpressed in MW and MP cells, respectively. Western blot analysis showed that the levels of WWOX and p53 protein in MW and MP cells were higher than in the blank control group. MTT assay showed that the cell proliferation ability of MW and MP cells was significantly lower than in the blank control group. Flow cytometry showed that 78.49% of MW and 66.76% of MP cells were arrested in the G0/G1 phase. Immunohistochemistry showed that mutant p53 was highly expressed in osteosarcoma, with a positive expression rate of 47.7%. The expression rate was positively correlated with the pathological grade of cancer. In conclusion, WWOX can affect the cell cycle of MG-63 osteosarcoma cells to inhibit cell proliferation, which provides new insights into gene therapy for osteosarcoma. The two types of the p53 gene have different functions in the development of osteosarcoma. Wild-type p53 acts as a tumor suppressor, while mutant p53, which is overexpressed in malignant osteosarcoma, has a carcinogenic effect associated with the degree of osteosarcoma.

The fragile site WWOX gene and the developing brain.

WWOX was cloned as a tumor suppressor gene mapping to chromosomal fragile site FRA16D. Loss of WWOX is closely related to tumorigenesis, cancer progression, and therapy resistance. Recent studies demonstrate the growing role of WWOX gene in other human pathologies such as metabolic and nervous system-related conditions. The neurologic phenotype of WWOX mutation includes seizures, ataxia, developmental delay, and spasticity of variable severity. WWOX is a ubiquitous protein with high expression in many tissues including brain, cerebellum, brain stem, and spinal cord. WWOX is highly expressed in different brain regions during murine fetal development and remained unchanged in the cortex and the corpus callosum in adult mice. The mechanism or the putative role of WWOX in the nervous system is still unclear but may include abnormal signaling protein, disruption of neuronal pathways, neuronal differentiation, mitochondrial dysfunction, or apoptosis. Homozygous mutations affecting WWOX in humans are likely to be more described in the future using exome sequencing. The described findings highlight that WWOX plays a critical role in normal central nervous system development and disease. The aim of this review is to summarize the roles of WWOX in the developing brain.

Effects of 5-Aza-2'-deoxycytidine on the methylation state and function of the WWOX gene in the HO-8910 ovarian cancer cell line.

The aim of this study was to explore the effects of 5-Aza-2'-deoxycytidine (5-Aza-CdR), a DNA methylation inhibitor, on the methylation state and function of the WWOX gene in the HO-8910 ovarian cancer cell line. The HO-8910 cells were divided into two groups, a control group and a 5-Aza-CdR-treated group. The methylation state of the WWOX gene was evaluated using a methylation-specific PCR assay. The effect of 5-Aza-CdR on the HO-8910 cells was analyzed using MTT and cell invasion assays, as well as flow cytometry. The animal models were established by intraperitoneal transplantation of the cells into nude mice. Following treatment with 5-Aza-CdR, a demethylation state was detected in the HO-8910 cells. WWOX protein expression was significantly higher in the 5-Aza-CdR-treated group compared with that in the control group. The cell growth rate at each tested time point and the number of invasive cells were lower in the 5-Aza-CdR-treated group compared with that in the control group. Flow cytometry revealed that 67.13% of the cells were arrested at the G0/G1 stage in the 5-Aza-CdR-treated group. The tumorigenic ability of the 5-Aza-CdR-treated group was lower compared with that of the control group. In conclusion, the methylation state of the WWOX gene in HO-8910 cells may be reversed using 5-Aza-CdR, which may also inhibit the growth of these cells.

Deletion and Mutation of WWOX Exons 6-8 in Human Non-small Cell Lung Cancer / 华中科技大学学报（医学）（英德文版）

To examine the deletion and point mutation of WWOX (WW domain containing oxidoreductase) exons 6-8 in human non-small cell lung cancer and their possible relationship with pathological stages, tumor tissues and the corresponding normal tissues were obtained from 44 Chinese patients who had undergone surgery for non-small cell lung cancer. RNA was extracted from each sample and deletion and mutation of WWOX exons 6-8 were analyzed by RT-PCR and DNA sequencing. Our results showed that 28 of 44 (63.6 %) lung cancer samples showed loss of WWOX exons 6-8 transcript and the deletion was detected in only 3 of 44 (6.8 %) corresponding adjacent normal tissues (P＜0.05). The transcript sequencing analyses of the 16 lung cancer samples without transcript loss of WWOX exons 6-8 revealed no difference from the sequence of GenBank. Moreover, the deletion of WWOX exons 6-8 was significantly higher in the smokers when compared with the non-smokers. It is also higher in the men and squamous carcinomas than in women and adenocarcinomas (P＜0.05). The deletion, however, was not found to be associated with pathological stages of the tumors. Our study documented a high incidence of deletion of WWOX exons 6-8 in non-small cell lung cancer in Chinese patients and suggested that the frequent loss of WWOX exons 6-8 might play an important role in the tumorigenesis of non-small cell lung cancer in Chinese. WWOX exons 6-8 may serves as a candidate molecular target of smoking carcinogenesis, and point mutation is not a predominant way of alteration of WWOX exons 6-8.

WWOX gene expression in non-small cell lung cancer and its clinical significance / 西安交通大学学报(医学版)

Objective To study the expression of WWOX gene in non-small cell lung cancer and its significance. Methods WWOX protein expression was evaluated by immunohistochemistry in 81 NSCLC patients(50 squamous cell carcinomas,31 adenocarcinomas and 20 adjacent normal lung tissues),and correlation with histopathologic(histotype,grade,tumor-node-metastasis,stage) and clinical characteristics was studied. Results WWOX expression was absent/reduced in 72.8% of NSCLC,whereas it was normal in 80.0% of adjacent normal lung tissues.WWOX expression was strongly associated with tumor histology and histologic grade(P

A study on expression changes of a tumor suppressor WWOX in human lung adenocarcinoma cell line A549 / 中国癌症杂志

Purpose:To detect the abnormalities of WWOX(WW domain containing oxidoreductase) gene in human lung adenocarcinoma cell line A549. Methods:Deletion of WWOX exons 6-8 transcript was analyzed by reverse transcriptase-PCR technology; loss of heterozygosity (LOH) of WWOX gene was analyzed by PCR-based assays for dinucleotide repeat polymorphisms technology. Aberrant expression of WWOX protein was analyzed by western blot. Results:A549 cells samples showed loss of WWOX exons 6-8 transcript.This deletion was not detected in normal primary cultured human bronchial epithelial cells samples.Three microsatellites(D16S3029、D16S3096、D16S504)did not have LOH in the normal primary cultured human bronchial epithelial cells samples, but D16S2029 and D16S3096 were all found to have LOH in A549 Cells samples. We further observed that expression of WWOX protein was significantly lower in A549 cell samples compared to the normal primary cultured human bronchial epithelial cells samples. Conclusions:WWOX gene may be important during tumorigenesis in lung adenocarcinoma cancer.Deletion of exons 6-8,LOH and aberrant expression of protein are all modes of WWOX gene inactivity in lung adenocarcinoma cancer.