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Cockayne syndrome (CS) is an autosomal recessive genetic disorder characterized by photosensitivity, developmental defects, neurological abnormalities, and premature aging. Mutations in CSA (ERCC8), CSB (ERCC6), XPB, XPD, XPG, XPF (ERCC4) and ERCC1 can give rise to clinical phenotypes resembling classic CS. Using a yeast two-hybrid (Y2H) screening approach, we identified LEO1 (Phe381-Ser568 region) as an interacting protein partner of full-length and C-terminal (Pro1010-Cys1493) CSB in two independent screens. LEO1 is a member of the RNA polymerase associated factor 1 complex (PAF1C) with roles in transcription elongation and chromatin modification. Supportive of the Y2H results, purified, recombinant LEO1 and CSB directly interact in vitro, and the two proteins exist in a common complex within human cells. In addition, fluorescently tagged LEO1 and CSB are both recruited to localized DNA damage sites in human cells. Cell fractionation experiments revealed a transcription-dependent, coordinated association of LEO1 and CSB to chromatin following either UVC irradiation or cisplatin treatment of HEK293T cells, whereas the response to menadione was distinct, suggesting that this collaboration occurs mainly in the context of bulky transcription-blocking lesions. Consistent with a coordinated interaction in DNA repair, LEO1 knockdown or knockout resulted in reduced CSB recruitment to chromatin, increased sensitivity to UVC light and cisplatin damage, and reduced RNA synthesis recovery and slower excision of cyclobutane pyrimidine dimers following UVC irradiation; the absence of CSB resulted in diminished LEO1 recruitment. Our data indicate a reciprocal communication between CSB and LEO1 in the context of transcription-associated DNA repair and RNA transcription recovery.

PURPOSE: To identify the disease-causing genes of Chinese Han women with idiopathic premature ovarian insufficiency (POI). METHODS: Seventy-four Chinese Han women with idiopathic POI were collected to analyze the genetic etiology. Triplet repeat-primed polymerase chain reaction (TP-PCR) was performed to screen the FMR1 (CGG)n premutation, and then 60 POI-related genes were sequenced by targeted next-generation sequencing (NGS) in POI patients with normal FMR1. RESULTS: A total of one patient (1/74) with FMR1 premutation was identified. Targeted NGS revealed that 15.07% (11/73) patients had pathogenic or likely pathogenic variants of Mendelian genes (FOXL2, EIF2B2, CYP17A1, CLPP, MCM9, GDF9, MSH5, ERCC6, POLG). Ten novel variants in six Mendelian genes were identified, such as CLPP c.355A>C (p.I119L) and c.688A>C (p.M230L), MCM9 c.1157C>T (p.T386M) and c.1291A>G (p.M431V), GDF9 c. 238C>T (p.Q80X), MSH5 c.604G>C (p.G202R) and c.2063T>C (p.I688T), ERCC6 c.C1769C>T (p.P590L), POLG c.2832G>C (p.E944D), and c.2821A>G (p.I941V). CONCLUSION: This study suggested targeted NGS was an efficient etiologic test for idiopathic POI patients without FMR1 premutation and enriched the variant spectrum of POI-related genes. SUPPLEMENTARY INFORMATION: The online version contains supplementary material available at 10.1007/s10815-021-02083-7.

Cockayne syndrome (CS) is a rare disease caused by mutations in ERCC6/CSB or ERCC8/CSA. We report here the clinical, genetic, and functional analyses of three unrelated patients mutated in ERCC6/CSB with a severe phenotype. After clinical examination, two patients were investigated via next generation sequencing, targeting seventeen Nucleotide Excision Repair (NER) genes. All three patients harbored a novel, c.3156dup, homozygous mutation located in exon 18 of ERCC6/CSB that affects the C-terminal region of the protein. Sanger sequencing confirmed the mutation and the parental segregation in the three families, and Western blots showed a lack of the full-length protein. NER functional impairment was shown by reduced recovery of RNA synthesis with proficient unscheduled DNA synthesis after UV-C radiations in patient-derived fibroblasts. Despite sharing the same mutation, the clinical spectrum was heterogeneous among the three patients, and only two patients displayed clinical photosensitivity. This novel ERCC6 variant in Tunisian patients suggests a founder effect and has implications for setting-up prenatal diagnosis/genetic counselling in North Africa, where this disease is largely undiagnosed. This study reveals one of the rare cases of CS clinical heterogeneity despite the same mutation. Moreover, the occurrence of an identical homozygous mutation, which either results in clinical photosensitivity or does not, strongly suggests that this classic CS symptom relies on multiple factors.

Human fibroblasts from a Cockayne Syndrome (CS) patient carrying the compound heterozygous c.1131 A > T and c.2571C > T within ERCC Excision Repair 6 (ERCC6) were reprogramed to generate integration-free induced pluripotent stem cells (iPSCs). Characterization of IUFi001-iPSCs demonstrated that this iPSC line is free of exogenous reprogrammed genes and maintains the genomic integrity. The pluripotency of IUFi001-iPSCs was confirmed by the expression of the pluripotency-associated markers and by embryoid body-based differentiation into cell types representative of the three germ layers. The generated iPSC line provides a powerful tool to dissect the molecular mechanisms underlying CS caused by mutations within ERCC6.

Cockayne syndrome (CS) is a rare autosomal recessive inherited disorder characterized by a variety of clinical features, including increased sensitivity to sunlight, progressive neurological abnormalities, and the appearance of premature aging. However, the pathogenesis of CS remains unclear due to the limitations of current disease models. Here, we generate integration-free induced pluripotent stem cells (iPSCs) from fibroblasts from a CS patient bearing mutations in CSB/ERCC6 gene and further derive isogenic gene-corrected CS-iPSCs (GC-iPSCs) using the CRISPR/Cas9 system. CS-associated phenotypic defects are recapitulated in CS-iPSC-derived mesenchymal stem cells (MSCs) and neural stem cells (NSCs), both of which display increased susceptibility to DNA damage stress. Premature aging defects in CS-MSCs are rescued by the targeted correction of mutant ERCC6. We next map the transcriptomic landscapes in CS-iPSCs and GC-iPSCs and their somatic stem cell derivatives (MSCs and NSCs) in the absence or presence of ultraviolet (UV) and replicative stresses, revealing that defects in DNA repair account for CS pathologies. Moreover, we generate autologous GC-MSCs free of pathogenic mutation under a cGMP (Current Good Manufacturing Practice)-compliant condition, which hold potential for use as improved biomaterials for future stem cell replacement therapy for CS. Collectively, our models demonstrate novel disease features and molecular mechanisms and lay a foundation for the development of novel therapeutic strategies to treat CS. Electronic supplementary material The online version of this article (10.1007/s13238-019-0623-2) contains supplementary material, which is available to authorized users.

Background: Cockayne syndrome is an autosomal recessive disorder caused by biallelic mutations in ERCC6 or ERCC8 genes. Aims: To study the clinical and mutation spectrum of Cockayne syndrome. Setting and Design: Medical Genetics Outpatient Department of Sanjay Gandhi Post Graduate Institute of Medical Sciences, Lucknow. This was a prospective study from 2007 to 2015. Materials and Methods: Clinical details were recorded, and sequencing of ERCC6 and ERCC8 were performed. Results and Conclusions: Of the six families, one family had a homozygous mutation in ERCC8 and the other five families had homozygous mutations in ERCC6. Novel variants in ERCC6 were identified in four families. Phenotypic features may vary from severe to mild, and a strong clinical suspicion is needed for diagnosis during infancy or early childhood. Hence, molecular diagnosis is needed for confirmation of diagnosis in a child with a suspicion of Cockayne syndrome. Prenatal diagnosis can be provided only if molecular diagnosis is established in the proband.

Cockayne syndrome (CS) is a DNA repair syndrome characterized by a broad spectrum of clinical manifestations such as neurodegeneration, premature aging, developmental impairment, photosensitivity and other symptoms. Mutations in Cockayne syndrome protein B (CSB) are present in the vast majority of CS patients and in other DNA repair-related pathologies. In the literature, the role of CSB in different DNA repair pathways has been highlighted, however, new CSB functions have been identified in DNA transcription, mitochondrial biology, telomere maintenance and p53 regulation. Herein, we present an overview of identified structural elements and processes that impact on CSB activity and its post-translational modifications, known to balance the different roles of the protein not only during normal conditions but most importantly in stress situations. Moreover, since CSB has been found to be overexpressed in a number of different tumors, its role in cancer is presented and possible therapeutic targeting is discussed.

Colorectal cancer (CRC) is a complex disease that can be caused by a spectrum of genetic variants ranging from low to high penetrance changes, that interact with the environment to determine which individuals will develop the disease. In this study, we sequenced 20 early-onset CRC patients to discover novel genetic variants that could be linked to the prompt disease development. Eight genes, CHAD, CHD1L, ERCC6, IGTB7, PTPN13, SPATA20, TDG and TGS1, were selected and re-sequenced in a further 304 early onset CRC patients to search for rare, high-impact variants. Although we found a recurring truncating variant in the TDG gene shared by two independent patients, the results obtained did not help consolidate any of the candidates as promising CRC predisposing genes. However, we found that potential risk alleles in our extended list of candidate variants have a tendency to appear at higher numbers in younger cases. This supports the idea that CRC onset may be oligogenic in nature and may show molecular heterogeneity. Further, larger and robust studies are thus needed to unravel the genetics behind early-onset CRC development, coupled with novel functional analyses and omic approaches that may offer complementary insight. This research was supported by Grants from Instituto de Salud Carlos III /FEDER: PI11/00681 (CRP), PI16/01057 (AC), PI17/00509 (CRP), PI17/00878 (SCB), PI19/00179 (CFR), PI19/01316 (JMC-T), PI20/01113 (SCB), PI20/00226 (CRP); CIBERONC-CB16/12/00234 (LV); and Fundación Olga Torres (LV and CFR); CERCA Program and Agència de Gestió d’Ajuts Universitaris i de Recerca (Generalitat de Catalunya, GRPRE 2017SGR21, GRC 2017SGR653). AL-N is supported by a Predoctoral Fellowship (GAIN, Xunta de Galicia, 2018 call) and IQ is supported by the FPI program of the Spanish Ministry of Science and Innovation—FEDER (SAF2016-80888-R). This article is based upon work from COST Action TransColonCan CA17118, supported by European Cooperation in Science and Technology (COST—www.cost.eu; www.transcoloncan.eu).

Up to 30% of all breast cancer cases may be inherited and up to 85% of those may be due to segregation of susceptibility genes with low and moderate risk [odds ratios (OR) ≤ 3] for (mostly peri- and post-menopausal) breast cancer. The majority of low/moderate-risk genes, particularly those with minor allele frequencies (MAF) of ERCC6 (main effect: 1.29 ≤ OR ≤ 2.91, 0.005 ≤ p ≤ 0.04, 11.8 ≤ MAF ≤ 40.9%), and implicated its interaction with ERCC8 (joint effect: 3.03 ≤ OR ≤ 5.31, 0.01 ≤ pinteraction ≤ 0.03). We found significant upregulation of ERCC6 (p = 7.95 × 10–6) and ERCC8 (p = 4.67 × 10–6) in breast cancer and similar frequencies of ERCC6 (1.8%) and ERCC8 (0.3%) mutations in breast tumors to known breast cancer susceptibility genes such as BLM (1.9%) and LSP1 (0.3%). Our integrative genomics approach suggests that ERCC6 may be a previously unreported low- to moderate-risk breast cancer susceptibility gene, which may also interact with ERCC8.

Background Cockayne syndrome (CS) is a rare autosomal recessive disorder characterized by growth failure and multisystemic degeneration. Excision repair cross‐complementation group 6 (ERCC6 OMIM: *609413) is the gene most frequently mutated in CS. Methods A child with pre and postnatal growth failure and progressive neurologic deterioration with multisystem involvement, and with nondiagnostic whole‐exome sequencing, was screened for causal variants with whole‐genome sequencing (WGS). Results WGS identified biallelic ERCC6 variants, including a previously unreported intronic variant. Pathogenicity of these variants was established by demonstrating reduced levels of ERCC6 mRNA and protein expression, normal unscheduled DNA synthesis, and impaired recovery of RNA synthesis in patient fibroblasts following UV‐irradiation. Conclusion The study confirms the pathogenicity of a previously undescribed upstream intronic variant, highlighting the power of genome sequencing to identify noncoding variants. In addition, this report provides evidence for the utility of a combination approach of genome sequencing plus functional studies to provide diagnosis in a child for whom a lengthy diagnostic odyssey, including exome sequencing, was previously unrevealing., Diagnosing rare diseases is quite challenging, especially when the phenotype deviates from what has been previously described and extensive testing including exome sequencing is negative. This study highlights the power of genome sequencing to identify noncoding variants that may be missed by exome sequencing as illustrated by the diagnosis of a child with Cockayne Syndrome found to have a novel upstream intronic ERCC6 variant.

Background Cockayne Syndrome (CS) is a rare autosomal recessive disorder characterized by neurological and sensorial impairment, dwarfism, microcephaly and photosensitivity. CS is caused by mutations in ERCC6 (CSB) or ERCC8 (CSA) genes. Methods Three patients with CS were referred to the Medical Genetics Unit of Saint Joseph University. Sanger sequencing of both ERCC8 and ERCC6 genes was performed: ERCC8 was tested in all patients while ERCC6 in one of them. Results Sequencing led to the identification of three homozygous mutations, two in ERCC8 (p.Y322* and c.843 + 1G > C) and one in ERCC6 (p.R670W). All mutations were previously reported as pathogenic except for the c.843 + 1G > C splice site mutation in ERCC8 which is novel. Conclusions Molecular diagnosis was established in all patients included in our study. A genotype-phenotype correlation is discussed and a link, between mutations and some specific religious communities in Lebanon, is suggested. Electronic supplementary material The online version of this article (10.1186/s12881-018-0677-7) contains supplementary material, which is available to authorized users.

Cockayne Syndrome (CS) is a rare neurodegenerative disease characterized by short stature, accelerated aging and short lifespan. Mutations in two human genes, ERCC8/CSA and ERCC6/CSB, are causative for CS and their protein products, CSA and CSB, while structurally unrelated, play roles in DNA repair and other aspects of DNA metabolism in human cells. Many clinical and molecular features of CS remain poorly understood, and it was observed that CSA and CSB regulate transcription of ribosomal DNA (rDNA) genes and ribosome biogenesis. Here, we investigate the dysregulation of rRNA synthesis in CS. We report that Nucleolin (Ncl), a nucleolar protein that regulates rRNA synthesis and ribosome biogenesis, interacts with CSA and CSB. In addition, CSA induces ubiquitination of Ncl, enhances binding of CSB to Ncl, and CSA and CSB both stimulate the binding of Ncl to rDNA and subsequent rRNA synthesis. CSB and CSA also increase RNA Polymerase I loading to the coding region of the rDNA and this is Ncl dependent. These findings suggest that CSA and CSB are positive regulators of rRNA synthesis via Ncl regulation. Most CS patients carry mutations in CSA and CSB and present with similar clinical features, thus our findings provide novel insights into disease mechanism.

Cockayne syndrome is a rare autosomal recessive neurodegenerative disorder caused by mutations of either the ERCC6/CSB or ERCC8/CSA genes. Here, we describe two sisters with Cockayne syndrome caused by compound heterozygous mutations in the ERCC8 gene using multimodal imaging. Significant ophthalmic and systemic phenotypic variability is discussed. Multimodal imaging was performed in two affected sisters and included electroretinography, optical coherence tomography, ultra-wide-field confocal scanning laser ophthalmoscopy, fundus autofluorescence and fluorescein angiography, and magnetic resonance imaging. Genetic analyses were performed on the affected sisters, both parents, and three unaffected siblings. The older sister (Patient 1) had mental retardation, bilateral hearing loss, ataxia, and decreased visual acuity with retinal dystrophy. Radiographic studies revealed microcephaly, cerebral and cerebellar atrophy, ventriculomegaly, and a diffusely thickened skull. Full-field electroretinography waveforms were severely diminished with attenuation of cone and rod responses. The younger sister (Patient 2) had similar clinical features, including ataxia, bilateral hearing loss, and decreased visual acuity with retinal dystrophy. She also had paranoid schizophrenia. Wide-field fundus autofluorescence showed scattered areas of retinal pigment epithelium atrophy, which was different from her sister. Genetic analysis revealed two mutations in the ERCC8 gene shared by the sisters. These include an unreported missense point mutation: p.Thr328Ser:c.983C > G, and another previously reported pathogenic missense mutation: p.Ala205Pro:c.613G > C. Familial testing showed in trans segregation of these mutations with unaffected siblings inheriting one or neither mutation, but not both. The clinical presentation and genetic studies confirmed a diagnosis of Cockayne syndrome in both sisters caused by compound heterozygous mutations in the ERCC8 gene on chromosome 10. Multimodal ocular imaging and systemic findings revealed wide phenotypic variability between the affected siblings.

BackgroundCockayne syndrome (CS) is a rare, autosomal recessive multisystem disorder characterised by prenatal or postnatal growth failure, progressive neurological dysfunction, ocular and skeletal abnormalities and premature ageing. About half of the patients with symptoms diagnostic for CS show cutaneous photosensitivity and an abnormal cellular response to UV light due to mutations in either the ERCC8/CSA or ERCC6/CSB gene. Studies performed thus far have failed to delineate clear genotype-phenotype relationships. We have carried out a four-centre clinical, molecular and cellular analysis of 124 patients with CS.Methods and resultsWe assigned 39 patients to the ERCC8/CSA and 85 to the ERCC6/CSB genes. Most of the genetic variants were truncations. The missense variants were distributed non-randomly with concentrations in relatively short regions of the respective proteins. Our analyses revealed several hotspots and founder mutations in ERCC6/CSB. Although no unequivocal genotype-phenotype relationships could be made, patients were more likely to have severe clinical features if the mutation was downstream of the PiggyBac insertion in intron 5 of ERCC6/CSB than if it was upstream. Also a higher proportion of severely affected patients was found with mutations in ERCC6/CSB than in ERCC8/CSA.ConclusionBy identifying >70 novel homozygous or compound heterozygous genetic variants in 124 patients with CS with different disease severity and ethnic backgrounds, we considerably broaden the CSA and CSB mutation spectrum responsible for CS. Besides providing information relevant for diagnosis of and genetic counselling for this devastating disorder, this study improves the definition of the puzzling genotype-phenotype relationships in patients with CS.

Cockayne syndrome is an autosomal recessive multisystem disorder characterized by intellectual disability, microcephaly, severe growth failure, sensory impairment, peripheral neuropathy, and cutaneous sensitivity. This rare disease is linked to disease-causing variations in the ERCC6 (CSB) and ERCC8 (CSA) genes. Various degrees of severity have been described according to age at onset and survival, without any clear genotype-phenotype correlation. All types of nucleotide changes have been observed in CS genes, including splice variations mainly affecting the splice site consensus sequences. We report here the case of two brothers from a consanguineous family presenting a severe but long-term survival phenotype of Cockayne syndrome. We identified in the patients a homozygous deep intronic nucleotide variation causing the insertion of a cryptic exon in the ERCC8 (CSA) transcript, by modifying intronic regulatory elements important for exon definition. The pathogenesis of the nucleotide variant NG_009289.1(NM_000082.3):c.173+1119G>C was validated in vitro with a reporter minigene system. To our knowledge, these are the first Cockayne patients described with this kind of disease-causing variation, though molecular mechanism underlying early onset symptoms and unexpected slow raise of progression of the disease remain to be elucidated.

// Jing-Jing Jing 1 , You-Zhu Lu 1 , Li-Ping Sun 1 , Jing-Wei Liu 1 , Yue-Hua Gong 1 , Qian Xu 1 , Nan-Nan Dong 1 and Yuan Yuan 1 1 Tumor Etiology and Screening Department of Cancer Institute and General Surgery, The First Affiliated Hospital of China Medical University, Key Laboratory of Cancer Etiology and Prevention, China Medical University, Liaoning Provincial Education Department, Shenyang, Liaoning, China Correspondence to: Yuan Yuan, email: yuanyuan@cmu.edu.cn Keywords: gastric cancer, ERCC6, ERCC8, SNP, expression Received: January 10, 2017 Accepted: April 12, 2017 Published: May 11, 2017 ABSTRACT Excision repair cross-complementing group 6 and 8 (ERCC6 and ERCC8) are two indispensable genes for the initiation of transcription-coupled nucleotide excision repair pathway. This study aimed to evaluate the interactions between single nucleotide polymorphisms of ERCC6 (rs1917799) and ERCC8 (rs158572 and rs158916) in gastric cancer and its precancerous diseases. Besides, protein level analysis were performed to compare ERCC6 and ERCC8 expression in different stages of gastric diseases, and to correlate SNPs jointly with gene expression. Sequenom MassARRAY platform method was used to detect polymorphisms of ERCC6 and ERCC8 in 1916 subjects. In situ ERCC6 and ERCC8 protein expression were detected by immunohistochemistry in 109 chronic superficial gastritis, 109 chronic atrophic gastritis and 109 gastric cancer cases. Our results demonstrated pairwise epistatic interactions between ERCC6 and ERCC8 SNPs that ERCC6 rs1917799- ERCC8 rs158572 combination was associated with decreased risk of chronic atrophic gastritis and increased risk of gastric cancer. ERCC6 rs1917799 also showed a significant interaction with ERCC8 rs158916 to reduce gastric cancer risk. The expressions of ERCC6, ERCC8 and ERCC6-ERCC8 combination have similarities that higher positivity was observed in chronic superficial gastritis compared with chronic atrophic gastritis and gastric cancer. As for the effects of ERCC6 and ERCC8 SNPs on the protein expression, single SNP had no correlation with corresponding gene expression, whereas the ERCC6 rs1917799– ERCC8 rs158572 pair had significant influence on ERCC6 and ERCC6-ERCC8 expression. In conclusion, ERCC6 rs1917799, ERCC8 rs158572 and rs158916 demonstrated pairwise epistatic interactions to associate with chronic atrophic gastritis and gastric cancer risk. The ERCC6 rs1917799– ERCC8 rs158572 pair significantly influence ERCC6 and ERCC6-ERCC8 expression.

In this study, we found that let-7c-5p expression was clearly downregulated in breast cancer tissues compared with that of corresponding adjacent tissues. Furthermore, overexpression of let-7c-5p in MCF-7 breast cancer cells could significantly inhibit cell proliferation and induce cell apoptosis. The target genes of let-7c-5p were predicted by the way of bioinformatics, and validated by dual luciferase reporter assay and western blotting demonstrating that excision repair cross complementing 6 (ERCC6) gene was a direct target. Collectively, the present study suggested that let-7c-5p acted as a tumor suppressor in breast cancer possibly by negatively regulating ERCC6, which took an important part in nucleotide excision repair and it may provide a new potential strategy for breast cancer therapy.

Objective To confirm diagnosis and explore the genetic aetiology in a Chinese patient suspected to have Cockayne syndrome (CS). Methods The patient was clinically examined, and the patient and her biological parents underwent genetic analysis using whole exome sequencing (WES) and Sanger sequencing. The foetus of the patient’s mother underwent prenatal diagnostic Sanger sequencing using amniotic fluid obtained at 19 weeks’ gestation. Results Clinical examination of the patient showed developmental delay, progressive neurologic dysfunction and premature aging. Two compound, heterozygous ERCC excision repair 6, chromatin remodelling factor (ERCC6) gene mutations were detected in the proband by WES and confirmed by Sanger sequencing, comprising a known paternal nonsense mutation (c.643G > T, p.E215X) and a novel maternal short insertion and deletion mutation (c.1614_c.1616delGACinsAAACGTCTT, p.K538_T539delinsKNVF). The patient was consequently diagnosed with CS type I. The foetus of the patient’s mother was found to carry only the maternally-derived c.1614_c.1616delGACinsAAACGTCTT variant. Conclusion This study emphasized the value of WES in clinical diagnosis, and enriched the known spectrum of ERCC6 gene mutations.

Background. To determine the impact of HTRA1 rs1120638, TIMP3 rs9621532, VEGFA rs833068, CFI rs10033900, ERCC6 rs3793784, and KCTD10 rs56209061 genotypes on the development of age-related macular degeneration (AMD) in the Lithuanian population. Methods. A total of 916 subjects were examined: 309 patients with early AMD, 301 patients with exudative AMD, and 306 healthy controls. The genotyping of HTRA1 rs11200638, TIMP3 rs9621532, VEGFA rs833068, CFI rs10033900, ERCC6 rs3793784, and KCTD10 rs56209061 was carried out using the RT-PCR method. Results. Our study showed that single-nucleotide polymorphisms rs3793784 and rs11200638 were associated with increased odds of early and exudative AMD, and the variant in KCTD10 (rs56209061) was found to be associated with decreased odds of early and exudative AMD development after adjustments for age and gender in early AMD analysis and after adjustments only for age in exudative AMD. The haplotype containing two minor alleles C-A and the G-A haplotype in rs3793784-rs11200638 were statistically significantly associated with an increased risk of exudative AMD development after adjustment for age, while the G-G haplotype showed a protective role against early and exudative AMD and the haplotype C-G in rs3793784-rs11200638 was associated with a decreased risk only of exudative AMD development. Conclusions. Our study identified two markers, rs11200638 and rs3793784, as risk factors for early and exudative AMD, and one marker, rs56209061, as a protective factor for early and exudative AMD development. The haplotypes constructed of rs3793784-rs11200638 were found to be associated with AMD development, as well.

Cancer-specific defects in DNA repair pathways create the opportunity to employ synthetic lethality approach. Recently, GEMA (gene expression and mutation analysis) approach detected insufficient expression of BRCA or NHEJ (non-homologous end joining) to predict PARP inhibitors response. We evaluated a possible role of DNA repair pathways using gene expression of single-strand break (XPA, XPC, XPG/ERCC5, CSA/ERCC8, and CSB/ERCC6) and double-strand break (ATM, BRCA1, BRCA2, RAD51, XRCC5, XRCC6, LIG4) in 92 patients with myelodysplastic syndrome (73 de novo, 9 therapy-related (t-MDS). Therapy-related MDS (t-MDS) demonstrated a significant downregulation of axis BRCA1-BRCA2-RAD51 comparing to normal controls (p = 0.048, p = 0.001, p = 0.001). XRCC6 showed significantly low expression in de novo MDS comparing to controls (p = 0.039) and for patients who presented chromosomal abnormalities (p = 0.047). Downregulation of LIG4 was consistently associated with poor prognostic markers in de novo MDS (hemoglobin

Cockayne syndrome (CS) is a multisystem degenerative disorder divided in 3 overlapping subtypes, with a continuous phenotypic spectrum: CS2 being the most severe form, CS1 the classical form and CS3 the late-onset form. Failure to thrive and growth difficulties are among the most consistent features of CS, leaving affected individuals vulnerable to numerous medical complications, including adverse effects of undernutrition, abrupt overhydration and overfeeding. There is thus a significant need for specific growth charts. We retrospectively collected growth parameters from genetically-confirmed CS1 and CS2 patients, used the GAMLSS package to construct specific CS growth charts compared to healthy children from WHO and CDC databases. Growth data were obtained from 88 CS patients with a total of 1626 individual growth data points. 49 patients were classified as CS1 and 39 as CS2 with confirmed mutations in CSB/ERCC6, CSA/ERCC8 or ERCC1 genes. Individuals with CS1 initially have normal growth parameters; microcephaly occurs from 2 months whereas onset of weight and height restrictions appear later, between 5 and 22 months. In CS2, growth parameters are already below standard references at birth or drop below the 5th percentile before 3 months. Microcephaly is the first parameter to show a delay, appearing around 2 months in CS1 and at birth in CS2. Height and head circumference are more severely affected in CS2 compared to CS1 whereas weight curves are similar in CS1 and CS2 patients. These new growth charts will serve as a practical tool to improve the nutritional management of children with CS.

Cockayne syndrome is caused by biallelic ERCC8 (CSA) or ERCC6 (CSB) mutations and is characterized by growth restriction, microcephaly, developmental delay, and premature pathological aging. Typically affected patients also have dermal photosensitivity. Although Cockayne syndrome is considered a DNA repair disorder, patients with UV-sensitive syndrome, with ERCC8 (CSA) or ERCC6 (CSB) mutations have indistinguishable DNA repair defects, but none of the extradermal features of Cockayne syndrome. We report novel missense mutations affecting a conserved loop in the ERCC6 (CSB) protein, associated with the Cockayne syndrome phenotype. Indeed, the amino acid sequence of this loop is more highly conserved than the adjacent helicase motifs V and VI, suggesting that this is a crucial structural component of the SWI/SNF family of proteins, to which ERCC6 (CSB) belongs. These comprise two RecA-like domains, separated by an interdomain linker, which interact through helicase motif VI. As the observed mutations are likely to act through destabilizing the tertiary protein structure, this prompted us to re-evaluate ERCC6 (CSB) mutation data in relation to the structure of SWI/SNF proteins. Our analysis suggests that antimorphic mutations cause Cockayne syndrome and that biallelic interdomain linker deletions produce more severe phenotypes. Based on our observations, we propose that further investigation of the pathogenic mechanisms underlying Cockayne syndrome should focus on the effect of antimorphic rather than null ERCC6 (CSB) mutations.

Background: Cockayne syndrome is a rare, autosomal recessive, multisystem disorder that causes a senile appearance. Ophthalmic abnormalities are frequently present. Here, we report a wide range of ocular findings in a child with Cockayne syndrome.Materials and methods: The systemic and ocular findings were reviewed. A mutation analysis was performed in the patient and her parents.Results: The patient underwent a complete ocular examination. Both eyes had low visual acuity, corneal epithelial degeneration, punctate opacities of the lens, and retina disorders. The systemic findings included growth deficiency and a senile appearance. Gene analysis showed mutations in exons 4 and 18 of the ERCC6 gene.Conclusion: Multiple ocular abnormalities were observed in a patient with Cockayne syndrome. A detailed ophthalmic evaluation of children with Cockayne syndrome is advised.

Excision repair cross-complementation (ERCC) enzymes are key members of the nucleotide excision repair pathway. Dysregulation of ERCC family members has been shown to be involved in chemoresistance in several malignancies. However, the function of ERCC6 in regulating chemo response has not been evaluated in colorectal cancer (CRC). We stably knocked down ERCC6 expression using short hairpin RNA (shRNA) in HCT116 and DLD1 human colon cancer cell lines, followed by chemosensitivity assay. In vivo chemosensitizing effects of ERCC6 were examined in xenograft experiments. Downregulation of ERCC6 conferred sensitivity to 5-fluorouracil (5-FU) in HCT116 and DLD1 cells. Stable knockdown of ERCC6 significantly enhanced antitumor activity of 5-FU in HCT116 xenograft mouse model. ERCC6 was upregulated in CRC tissues compared to matched noncancerous adjacent tissues and was also upregulated in patients who were resistant to 5-FU treatment. In addition, high expression of ERCC6 was associated with poor overall survival in CRC patients with or without receiving 5-FU therapy. Elevated expression of ERCC6 contributes to chemoresistance in CRC cells. Low ERCC6 expression is associated with better chemo response and survival in CRC patients. Therefore, this protein represents a novel therapeutic target for improvement of chemotherapeutic efficacy and predictive biomarker for patient survival.

Background. DNA helicases maintain genome stability, and their deficiency is associated with disorders resembling premature aging as well as contributes to carcinogenesis. Their functions are determined by the respective genes encoding nucleotide excision repair initiating proteins, e.g. XPD and CSB. Objective. The present study aimed to investigate the influence of genetic variations in ERCC2/XPD (rs1799793, rs13181) and ERCC6/CSB (rs2228526, rs2228528) loci on lifespan and developing age-related bladder cancer focusing on homozygous wild type alleles. Method. The allelic variants were identified in 354 clinically healthy controls and 418 bladder cancer patients using the PCR-RFLP method. Results. The age-depended increase in frequencies of homozygous carriers of wild-type XPD 312Asp and XPD 751Lys alleles was observed among controls, especially among subjects over 80 years (r = 0.67, p = 0.012). The statistically significant correlation was also found between the frequency of homozygous wild type alleles at all tested loci and age in healthy population over 60 years (r = 0.35, p = 0.046) suggesting the relationship between lifespan and longevity, on the one hand, and normal functioning of these genes and their products, on the other hand. Homozygous carriers of wild type alleles were less susceptible to bladder cancer, tumor invasion, increase in grade of malignancy and recurrence, but their effects were specific with respect to clinicopathological and lifestyle characteristics. Conclusion. Homozygous wild type alleles encoding XPD and CSB proteins with optimal properties were shown to affect human lifespan, risk of developing bladder cancer, its progression and recurrence under certain conditions.

Cockayne syndrome is an autosomal recessive disorder principally characterized by postnatal growth failure and progressive neurological dysfunction, due primarily to mutations in ERCC6 and ERCC8. Here, we report our diagnostic experience for two patients in a Chinese family suspected on clinical grounds to have Cockayne syndrome. Using multiple molecular techniques, including whole exome sequencing, array comparative genomic hybridization and quantitative polymerase chain reaction, we identified compound heterozygosity for a maternal splicing variant (chr5:60195556, NM_000082:c.618-2A > G) and a paternal complex deletion/inversion/deletion rearrangement removing exon 4 of ERCC8, confirming the suspected pathogenesis in these two subjects. Microhomology (TAA and AGCT) at the breakpoints indicated that microhomology-mediated FoSTeS events were involved in this complex ERCC8 rearrangement. This diagnostic experience illustrates the value of high-throughput genomic technologies combined with detailed phenotypic assessment in clinical genetic diagnosis.

The study of DNA base and nucleotide excision repair gene polymorphisms in bladder cancer seems to have a predictive value because of the evident relationship between the DNA damage response induced by environmental mutagens and cancer predisposition.The objective was to determine OGG1 Ser326Cys, XRCC1 Arg399Gln, XPD Asp312Asn, and ERCC6 Met1097Val polymorphisms in bladder cancer patients as compared to controls.Both groups were predominantly represented by Belarusians and Eastern Slavs. DNA samples from 336 patients and 370 controls were genotyped using a PCR-RFLP method.The genotype distributions were in agreement with the Hardy-Weinberg equilibrium. The minor allele frequencies in the control population were in the range of those in Caucasians in contrast to Asians. The OGG1 326 Ser/Cys and XPD 312 Asp/Asn heterozygous genotypes were inversely associated with cancer risk (OR [95% CI] = 0.69 [0.50-0.95] and 1.35 [1.0-1.82], respectively). The contrasting effects of these genotypes were potentiated due to their interactions with smoking habit or age.Among four DNA repair gene polymorphisms, the OGG1 326 Ser/Cys and XPD 312 Asp/Asn heterozygous genotypes might be recognized as potential genetic markers modifying susceptibility to bladder cancer in Belarus.

The Repeat Expansion Diseases (REDs) are human genetic disorders that arise from expansion of a tandem repeat tract. The Fragile X-related disorders are members of this disease group in which the repeat unit is CGG/CCG and is located in the 5′ untranslated region of the FMR1 gene. Affected individuals often show mosaicism with respect to repeat number resulting from both expansion and contraction of the repeat tract, however, the mechanism responsible for these changes in repeat number are unknown. Work from a variety of model systems suggests that Transcription Coupled Repair (TCR) may contribute to repeat instability in diseases resulting from CAG/CTG-repeat expansion. To test whether TCR could contribute to repeat instability in the Fragile X-related disorders, we tested the effect of mutations in Csb (Cockayne Syndrome group B), a gene essential for TCR, in a knock-in mouse model of these disorders. We found that the loss of CSB affects expansions in a gender and cell type-specific manner. Our data also show an unanticipated gender difference in instability even in Csb+/+ animals that may have implications for our understanding of the mechanism of repeat expansion in the FX mouse model and perhaps for humans as well.

The effects of polymorphisms in ERCC5, ERCC6, XPC, CCNH and MMS19L on osteosarcoma response to chemotherapy and the survival of the affected patients were assessed. Genotyping of ERCC5, ERCC6, XPC, CCNH and MMS19L was performed by PCR-RFLP assay. The median PFS was 12.8 months, and the median OS was 18.6 months. Individuals carrying homozygous genotypes of ERCC5 rs17655 and ERCC5 rs1047768 were more like to have good response to treatment, while those carrying homozygous genotypes of MMS19L rs29001322 showed poor response. Osteosarcoma patients carrying TT genotype of ERCC5 rs1047768 showed a significantly longer PFS (16.8 months) and OS (21.4 months) than CC genotype, with HRs(95% CI) of 0.31 (0.10-0.93) and 0.32 (0.06-0.97), respectively. Conversely, those with the TT genotype of MMS19L rs29001322 demonstrated shorter PFS and OS, the HRs (95% CI) being 2.23 (1.08-4.15) and 4.62 (1.45-16.08), respectively. Our findings showed polymorphisms in ERCC5 rs1047768 and MMS19L rs29001322 to be associated with clinical outcome of osteosarcoma patients undergoing chemotherapy.

Background Deficient nucleotide excision repair (NER) activity causes a variety of autosomal recessive diseases including xeroderma pigmentosum (XP) a disorder which pre-disposes to skin cancer, and the severe multisystem condition known as Cockayne syndrome (CS). In view of the clinical overlap between NER-related disorders, as well as the existence of multiple phenotypes and the numerous genes involved, we developed a new diagnostic approach based on the enrichment of 16 NER-related genes by multiplex amplification coupled with next-generation sequencing (NGS). Methods Our test cohort consisted of 11 DNA samples, all with known mutations and/or non pathogenic SNPs in two of the tested genes. We then used the same technique to analyse samples from a prospective cohort of 40 patients. Multiplex amplification and sequencing were performed using AmpliSeq protocol on the Ion Torrent PGM (Life Technologies). Results We identified causative mutations in 17 out of the 40 patients (43 %). Four patients showed biallelic mutations in the ERCC6(CSB) gene, five in the ERCC8(CSA) gene: most of them had classical CS features but some had very mild and incomplete phenotypes. A small cohort of 4 unrelated classic XP patients from the Basque country (Northern Spain) revealed a common splicing mutation in POLH (XP-variant), demonstrating a new founder effect in this population. Interestingly, our results also found ERCC2(XPD), ERCC3(XPB) or ERCC5(XPG) mutations in two cases of UV-sensitive syndrome and in two cases with mixed XP/CS phenotypes. Conclusions Our study confirms that NGS is an efficient technique for the analysis of NER-related disorders on a molecular level. It is particularly useful for phenotypes with combined features or unusually mild symptoms. Targeted NGS used in conjunction with DNA repair functional tests and precise clinical evaluation permits rapid and cost-effective diagnosis in patients with NER-defects. Electronic supplementary material The online version of this article (doi:10.1186/s13023-016-0408-0) contains supplementary material, which is available to authorized users.

Nucleotide excision repair (NER) is responsible for protecting DNA in skin cells against UVR-induced damage. Using a candidate pathway approach, a matched case–control study nested within a prospective, community-based cohort was carried out to test the hypothesis that single-nucleotide polymorphisms (SNPs) in NER genes are associated with susceptibility to non-melanoma skin cancer (NMSC). Histologically confirmed cases of NMSC ( n =900) were matched to controls ( n =900) on the basis of age, gender, and skin type. Associations were measured between NMSC and 221 SNPs in 26 NER genes. Using the additive model, two tightly linked functional SNPs in ERCC6 were significantly associated with increased risk of NMSC: rs2228527 (odds ratio (OR) 1.57, 95% confidence interval (CI) 1.20–2.05) and rs2228529 (OR 1.57, 95% CI 1.20–2.05). These associations were confined to basal cell carcinoma (BCC) of the skin (rs2228529, OR 1.78, 95% CI 1.30–2.44; rs2228527, OR 1.78, 95% CI 1.31–2.43). These hypothesis-generating findings suggest that functional variants in ERCC6 may be associated with an increased risk of NMSC that may be specific to BCC.

UV-sensitive syndrome (UV SS) is a genodermatosis characterized by cutaneous photosensitivity without skin carcinoma. Despite mild clinical features, cells from individuals with UV SS, like Cockayne syndrome cells, are very UV sensitive and are deficient in transcription-coupled nucleotide-excision repair (TC-NER), which removes DNA damage in actively transcribed genes. Three of the seven known UV SS cases carry mutations in the Cockayne syndrome genes ERCC8 or ERCC6 (also known as CSA and CSB, respectively). The remaining four individuals with UV SS, one of whom is described for the first time here, formed a separate UV SS-A complementation group; however, the responsible gene was unknown. Using exome sequencing, we determine that mutations in the UVSSA gene (formerly known as KIAA1530) cause UV SS-A. The UVSSA protein interacts with TC-NER machinery and stabilizes the ERCC6 complex; it also facilitates ubiquitination of RNA polymerase IIo stalled at DNA damage sites. Our findings provide mechanistic insights into the processing of stalled RNA polymerase and explain the different clinical features across these TC-NERg-deficient disorders., Nature Genetics, 44(5), pp.586-592; 2012

The Cockayne syndrome is a rare autosomal recessive disease characterized by a general developmental delay, the unique face, and abnormal skin sensitivity to sunlight. It belongs to the family of disorders of the nucleotide excision repair system. Mutations of the ERCC6 and ERCC8 genes are the predominant cause of the Cockayne syndrome, whereby the ERCC6 gene mutation makes up approximately 70% of the cases. We report a Chinese case of a classic Cockayne syndrome, carrying the novel nonsense mutation c.1387C>T/Q463X in the ERCC6 gene in an apparently homozygous status. This mutation was found in a heterozygous status in this patient’s father, while the mother carried two wild-type ERCC6 alleles. A further molecular investigation of the family revealed that there was a de novo microdeletion including the ERCC6 gene of maternal origin in the proband. The determination of the deletion breakpoints by Illumina genome-wide DNA analysis beadchip showed that the deletion spanned 2.82 Mb in size. This case adds to the mutation spectrum of this DNA repair disorder.

The purpose of this study was to explore the variation in DNA repair genes in adults with WHO grade II and III gliomas and their relationship to patient survival. We analysed a total of 1,458 tagging single-nucleotide polymorphisms (SNPs) that were selected to cover DNA repair genes, in 81 grade II and grade III gliomas samples, collected in Sweden and Denmark. The statistically significant genetic variants from the first dataset (P < 0.05) were taken forward for confirmation in a second dataset of 72 grade II and III gliomas from northern UK. In this dataset, eight gene variants mapping to five different DNA repair genes (ATM, NEIL1, NEIL2, ERCC6 and RPA4) which were associated with survival. Finally, these eight genetic variants were adjusted for treatment, malignancy grade, patient age and gender, leaving one variant, rs4253079, mapped to ERCC6, with a significant association to survival (OR 0.184, 95% CI 0.054-0.63, P = 0.007). We suggest a possible novel association between rs4253079 and survival in this group of patients with low-grade and anaplastic gliomas that needs confirmation in larger datasets.