Chromodomain Helicase DNA-binding Protein 7 Gene Research Articles

Combined pituitary hormone deficiency harboring CHD7 gene missense mutation without CHARGE syndrome: a case report

BackgroundHeterozygous loss-of-function mutations in the chromodomain helicase DNA-binding protein 7 (CHD7) gene cause CHARGE syndrome characterized by various congenital anomalies. A majority of patients with CHARGE syndrome present with congenital hypogonadotropic hypogonadism (HH), and combined pituitary hormone deficiency (CPHD) can also be present. Whereas CHD7 mutations have been identified in some patients with isolated HH without a diagnosis of CHARGE syndrome, it remains unclear whether CHD7 mutations can be identified in patients with CPHD who do not fulfill the criteria for CHARGE syndrome.Case presentationA 33-year-old woman was admitted to our hospital. She had primary amenorrhea and was at Tanner stage 2 for both pubic hair and breast development. She was diagnosed with CPHD (HH, growth hormone deficiency, and central hypothyroidism), and a heterozygous rare missense mutation (c.6745G > A, p.Asp2249Asn) in the CHD7 gene was identified. Our conservation analysis and numerous in silico analyses suggested that this mutation had pathogenic potential. She had mild intellectual disability, a minor feature of CHARGE syndrome, but did not fulfill the criteria for CHARGE syndrome.ConclusionsWe report a rare case of CPHD harboring CHD7 mutation without CHARGE syndrome. This case provides valuable insights into phenotypes caused by CHD7 mutations. CHD7 mutations can have a continuous phenotypic spectrum depending on the severity of hypopituitarism and CHARGE features. Therefore, we would like to propose a novel concept of CHD7-associated syndrome.

Two novel CHD7 variants in patients with typical and mild features of CHARGE syndrome co-occurring with esophageal atresia

CHARGE syndrome ( C oloboma, H eart defect, A tresia of the choanae, growth R etardation, G enital abnormalities, E ar anomalies/deafness) is a rare genetic autosomal dominant disease with a prevalence of 1/10,000 live births. It is associated with pathogenic variants in the chromodomain-helicase-DNA-binding protein 7 ( CHD7 ) gene. Although CHARGE syndrome is known to be associated with esophageal atresia (EA) and tracheoesophageal fistulas in 15–20% of cases, there are only a few clinical and molecular case descriptions of CHARGE syndrome in the context of EA. We present two individuals with novel CHD7 variants with variable clinical expression of CHARGE syndrome co-occurring with EA. Individual 1 had typical CHARGE syndrome, and a rare type D EA that required direct anastomosis repair. Genetic testing revealed a likely pathogenic essential splice site variant, c.4644+1G > T. Individual 2 had a mild CHARGE phenotype and a type A EA that required complex repair via the Foker process. The described expression of previously unreported typical CHD7 variants expands the current knowledge of CHARGE syndrome co-occurring with EA that could help with future patient care and genetic counseling. We hope that the description of the previously unreported variant of uncertain significance with a mild CHARGE phenotype will assist future classification efforts of this variant. • Novel report of two variants in CHD7 gene with wide clinical symptom variability. • Two clinical cases of CHARGE syndrome co-occurring with esophageal atresia. • Call to attention for genetic studies in infants born with esophageal atresia. • Call for innovations to public database of locus specific CHD7 variants.

Discovery of Novel Variants on the CHD7 Gene: A Case Series of CHARGE Syndrome.

Background: CHARGE syndrome (CS) is a single-gene genetic disorder with multiple organ malformations caused by a variant of the chromodomain helicase DNA-binding protein 7 (CHD7) gene on chromosome 8q12.1. In this study, we aimed to investigate new variants that have emerged in these cases compared with typical CS and the relationship between the genes and phenotypes. Methods: Patients with suspected genetic diseases were subjected to Whole Exome Sequencing (WES) at a genetics laboratory in Guangzhou. The average sequencing coverage depth was >200 ×, and 96% was >20 ×. The variant interpretation was manipulated according to the American College of Medical Genetics (ACMG) guidelines. Molecular data on databases for ClinVar and CHD7 were also collected and collated. We reviewed the currently described CHD7 variants and analyzed the genetic variation and phenotypic heterogeneity. Results: Data of 12 patients with CS from four hospitals in China were collected. According to gestational age, most of them (8/12) were near-term babies with a lower birth weight than their peers, averaging 2.62 kg. In this study, the most common phenotypes were respiratory tract malformations (11/12), heart malformations (10/12), and central nervous system malformations (9/12). Two fetuses were confirmed to have brain or heart abnormalities during prenatal testing, while 10/12 were found to have abnormalities during prenatal testing. The maximum Acute Physiology and Chronic Health Evaluation (APACHE II) score at admission was 19, and the average was 11.58. Five variants in the CHD7 gene c.7012C > T (p.Q2338*), c.7868delC (p.P2623Rfs*16), c.5405-3C > G, c.6936 + 2T > C, and c.8077-2A > G) were novel and were located in exons 33, 36, and introns 25, 32, and 37, respectively. There may be a positive correlation between exon location and phenotype. Conclusion: Five novel variants were discovered. These expanded the mutational spectrum of the CHD7 gene and the phenotype of CS. There may be a correlation between the new mutation sites and the phenotype, which has some reference value for the evaluation of mutation sites.

De novo Splice Site Mutation of the CHD7 Gene in a Chinese Patient with Typical CHARGE Syndrome

Introduction: CHARGE syndrome (CS, OMIM 214800) is a rare genetic disease characterized by multiple congenital abnormalities, including coloboma, heart defect, atresia of the choanae, retardation of development, genital anomalies, and ear anomalies/deafness. The syndrome is mainly caused by a heterozygous variant in the chromodomain helicase DNA-binding protein 7 (CHD7) gene that encodes the CHD7 protein, involved in the ATP-dependent remodeling of chromatin. Methods: In this study, the next-generation sequencing targeted panel was used to detect a de novo variant c.3523-2A>G in the CHD7 gene in a patient with severe CS, congenital heart disease, left coloboma of the choroid, cryptorchidism, and congenital deafness. The Sanger sequencing confirmed the variant and clarified it as de novo variant by short tandem repeat analysis in the patient family. We analyzed the effect of a variant by Minigene assay to evaluate the pathogenicity of the variant. Results: In summary, cDNA analysis confirmed that c.3523-2A>G variant activates a cryptic splice site, resulting in 172 base pair missing in exon 15, leading to the premature truncation of the CHD7 protein (p.V1175Afs*11). Conclusion: The present study functionally characterized the novel c.3523-2A>G variant in CHD7, providing further confirmatory evidence that it is associated with CS.

The eye - the window to the soul of the diagnosis: CHARGE Syndrome, a case report

The modality of inheritance in CHARGE syndrome is autosomal dominant, classically triggered by mutations in the chromo-domain helicase DNA binding protein-7 (CHD7) gene. CHARGE syndrome is characterized by the variable occurrence of coloboma, heart defects, atresia of the choanae, retarded growth and development, genital hypoplasia, ear anomalies and deafness. In this report, we describe an infant with a typical phenotype characterized by severe psychomotor retardation, facial asymmetry, coloboma, cortical blindness, unilateral choanal atresia, congenital heart anomalies, genital hypoplasia, cranial nerve IX/X dysfunction and global developmental delay that was diagnosed clinically. Following clinical diagnosis a complete sequencing of the CHD7 gene was carried out at the Institute for Medical Diagnostics GmbH in Ingelheim, Germany. Genomic DNA was screened for mutations in the CD7 gene (OMMIM 608892) on chromosome 8q12.1 The codon exon 2-38 and the respective exon-intron boundaries were amplified by polymerase chain reaction and analysed by direct sequencing. Resulting sequence data were compared with the reference sequence NM_017880.3 No mutation in CHD7 gene was detected as a genetic cause for the clinical phenotype of the patient. The MPLA multiplex ligation-dependent probe amplification analysis showed no copy number variation in the CHD7 gene. This case report underscores the importance of a detailed family history and physical examination in the diagnosis of CHARGE syndrome. Additionally, it provides valuable insight into the pathogenesis and clinical presentation of the syndrome as well as highlighting the benefits of a multidisciplinary approach. With supportive nurturing care, children with CHARGE syndrome can overcome the associated disabilities and develop necessary motor skills and a life-style enhancing level of fitness.

A Novel N-terminal Region to Chromodomain in CHD7 is Required for the Efficient Remodeling Activity

Chromodomain-Helicase DNA binding protein 7 (CHD7) is an ATP dependent chromatin remodeler involved in maintaining open chromatin structure. Mutations of CHD7 gene causes multiple developmental disorders, notably CHARGE syndrome. However, there is not much known about the molecular mechanism by which CHD7 remodels nucleosomes. Here, we performed biochemical and biophysical analysis on CHD7 chromatin remodeler and uncover that N-terminal to the Chromodomain (N-CRD) interacts with nucleosome and contains a high conserved arginine stretch, which is reminiscent of arginine anchor. Importantly, this region is required for efficient ATPase stimulation and nucleosome remodeling activity of CHD7. Furthermore, smFRET analysis shows the mutations in the N-CRD causes the defects in remodeling activity. Collectively, our results uncover the functional importance of a previously unidentified N-terminal region in CHD7 and implicate that the multiple domains in chromatin remodelers are involved in regulating their activities.

CHD7 missense variants and clinical characteristics of Chinese males with infertility.

BackgroundIsolated hypogonadotropic hypogonadism (IHH) and Kallmann syndrome (KS) are rare genetic diseases that cause male infertility. The chromodomain helicase DNA‐binding protein 7 (CHD7) gene is commonly associated with KS and IHH. We speculated that CHD7 variants may be associated with male infertility.MethodsTwo hundred males with azoospermia and 120 with oligozoospermia were recruited. The patients underwent clinical examination and reproductive hormone testing. A panel of genes including CHD7 and others related to spermatogenic failure was sequenced by targeted‐gene exome sequencing.ResultsThree patients with severe oligozoospermia had CHD7 variants (a detection rate of 0.94% (3/320)). After prediction software analysis, two of the variants c.3464G>A (p.R1155H) and c.4516G>A (p.G1506S) were predicted to be likely pathogenic. Although predicted to be benign, the variants of c.2824A>G (p.T942A) located in the chromodomain 2 could not be excluded as disease causing. The patients with variants had small testicular volumes. In particular, the testes of the patient with a p.G1506S variant varied in size (left, 8 ml; right, 4.5 ml). Two patients (patients 31 and 120) had low E2 levels and two (patients 83 and 120) had low T levels. Ultimately, these variants were classified as “variants of unknown significant” that may be associated with male infertility.ConclusionsThere may be a relationship between the CHD7 gene missense variants and male infertility. These variants are easier to find in patients with azoospermia and severe oligospermia whose testosterone levels are decreased.

MON-355 Charge Syndrome: Unusual Cause of Hypogonadism Leading to Osteoporosis

CHARGE syndrome is an unusual cause of hypogonadism; it is characterized by coloboma, heart defect, ateresia choanae, retarded growth and development, genital hypoplasia and ear anomalies. Two-thirds of affected patients have a mutation within the chromodomain helicase DNA-binding protein-7 gene, which is involved in embryonic development. The involvement of this gene in the pathogenesis of isolated idiopathic hypogonadotropic hypogonadism (HH) has been postulated. The reported incidence of this syndrome ranges from 0.1–0.2/10000 (1).A 24 year old female presented to our facility for further management of her HH and osteoporosis in the setting of her CHARGE syndrome. She was born full-term and diagnosed with this condition at the age of 6. Formal genetic testing as an adult demonstrated mutation within the CHD7 gene (chr 8:61,757,970). She had delayed puberty secondary to her hypogonadism; she was not treated with HRT as benefits were not considered significantly sufficient. She subsequently developed osteoporosis at the age of 20 which was treated at an outside facility with pamidronate IV Q4 months along with calcium and Vitamin D supplementation. Her initial Dual-energy X-ray absorptiometry (DXA) showed scoliosis in the lumbar spine [bone mass density (BMD): 0.514,osteoporosis by Z-score] with total hip showing BMD: 0.738,osteopenia by Z-score. Follow-up DXA after 3 years showed statistically significant improvement in bone mineralization of her L-spine [BMD: 0.595, +16%] and total hip [BMD: 0.777, +13.5%]. She presented to our facility in 2018 with labs showing normal calcium and 25-OH D; treatment with pamidronate was continued. She had a repeat DXA in 2019 which showed Z-scores of 0 in the left and right femoral necks. She was given the option of continued treatment for her osteoporosis versus monitoring and chose the latter with follow-up DXA.Hypogonadotropic hypogonadism is associated with delays in puberty or pubertal arrest. Luteinizing Hormone Releasing Hormone and HCG tests should be performed within the four months of life or at puberty in cases of hypogenitalism. GH deficiency should be investigated as a cause for growth retardation with GH stimulation levels. Hormone replacement is often required at puberty for females and is indicated for prevention of osteoporosis. Radiological testing with DXA scan should be included. Early proper endocrinological assessment and management is essential for adequate sexual development in these patients; this leads to improved overall quality of life along with prevention of serious morbidities, including bone demineralization (2).1. Blake K D, Prasad C. CHARGE syndrome. Orphanet Journal of Rare Diseases 2006, 1:34.2. Foppiani L, Maffe A. CHARGE syndrome as unusual cause of hypogonadism: endocrine and molecular evaluation. Andrologia (2010). 42: 326–330.

Feeding difficulty is the dominant feature in 12 Chinese newborns with CHD7 pathogenic variants

BackgroundCHARGE syndrome is characterized by coloboma, heart defects, choanal atresia, growth retardation, genitourinary malformation and ear abnormalities. The chromodomain helicase DNA-binding protein 7 (CHD7) gene is the major cause of CHARGE syndrome and is inherited in an autosomal dominant manner. Currently, the phenotype spectrum of CHARGE syndrome in neonatal population remain elusive. We aimed to investigate the phenotype spectrum of neonatal patients suspected to have CHARGE syndrome with pathogenic or likely pathogenic variants in the CHD7 gene.MethodsWe pooled next-generation sequencing data from the Neonatal Birth Defects Cohort (NBDC, ClinicalTrials.gov Identifier: NCT02551081) in Children’s Hospital of Fudan University. The pathogenicity of novel variants was analyzed by bioinformatic and genetic analyses. Clinical information collection, Sanger sequencing and follow-up interviews were performed when possible. Cranial MRI of these patients was performed, the volumes of different regions of the brain were analyzed.ResultsA total of 12 unrelated patients in our cohort were found with CHD7 variants. Eight patients received a firm clinical diagnosis of CHARGE syndrome (Bergmann criteria, Blake criteria, Verloes criteria and Hale criteria). Three patients did not match any diagnostic criteria, and no patients matched the Verloes criteria. Phenotype spectrum analysis found that feeding difficulty was the dominant feature among this neonatal cohort. Six novel variants in the CHD7 gene (Glu2408*, Lys651*, c.5607 + 1G > T, Leu373Val, Lys2005Asnfs*37 and Gln1991*) were identified, expanding the variant database of the CHD7 gene. Cranial MRI analysis revealed significant volume loss in cingulate gyrus, occipital lobe, and cerebellum and volume gain in the left medial and inferior temporal gyri anterior white matter parts.ConclusionsBased on a relatively unbiased neonatal cohort, we concluded that CHARGE syndrome and CHD7 gene variants should be suspected in newborns who have feeding difficulty, and one or more malformations.Trial registrationNeonatal Birth Defects Cohort (NBDC, ClinicalTrials.gov identifier: NCT02551081).

Chromodomain Helicase DNA-Binding Protein 7 Is Suppressed in the Perinecrotic/Ischemic Microenvironment and Is a Novel Regulator of Glioblastoma Angiogenesis.

Tumorigenic and non-neoplastic tissue injury occurs via the ischemic microenvironment defined by low oxygen, pH, and nutrients due to blood supply malfunction. Ischemic conditions exist within regions of pseudopalisading necrosis, a pathological hallmark of glioblastoma (GBM), the most common primary malignant brain tumor in adults. To recapitulate the physiologic microenvironment found in GBM tumors and tissue injury, we developed an in vitro ischemic model and identified chromodomain helicase DNA-binding protein 7 (CHD7) as a novel ischemia-regulated gene. Point mutations in the CHD7 gene are causal in CHARGE syndrome (a developmental disorder causing coloboma, heart defects, atresia choanae, retardation of growth, and genital and ear anomalies) and interrupt the epigenetic functions of CHD7 in regulating neural stem cell maintenance and development. Using our ischemic system, we observed microenvironment-mediated decreases in CHD7 expression in brain tumor-initiating cells and neural stem cells. Validating our approach, CHD7 was suppressed in the perinecrotic niche of GBM patient and xenograft sections, and an interrogation of patient gene expression datasets determined correlations of low CHD7 with increasing glioma grade and worse patient outcomes. Segregation of GBM by molecular subtype revealed a novel observation that CHD7 expression is elevated in proneural versus mesenchymal GBM. Genetic targeting of CHD7 and subsequent gene ontology analysis of RNA sequencing data indicated angiogenesis as a primary biological function affected by CHD7 expression changes. We validated this finding in tube-formation assays and vessel formation in orthotopic GBM models. Together, our data provide further understanding of molecular responses to ischemia and a novel function of CHD7 in regulating angiogenesis in both neoplastic and non-neoplastic systems. Stem Cells 2019;37:453-462.

Three Novel Mutations of CHD7 Gene in Two Turkish Patients with Charge Syndrome; A Double Point Mutation and an Insertion

The CHARGE (coloboma, heart defects, atresia, retardation, genital, ear) syndrome is a genetic disease characterized by ocular coloboma, choanal atresia or stenosis and semicircular canal abnormalities. Most of the patients clinically diagnosed with CHARGE syndrome have mutations in chromodomain helicase DNA-binding protein 7 (CHD7) gene. The CHD7 gene is located on chromosome 8q12.1, and up to now, there are more than 500 pathogenic mutations identified in the literature. We report two patients diagnosed with CHARGE syndrome with two novel mutations in the CHD7 gene: the first patient has double consecutive novel mutations in three adjacent codons, and the other has a novel insertion.

Identification of a novel mutation in theCHD7gene in a patient with CHARGE syndrome

CHARGE syndrome has been estimated to occur in 1:10,000 births worldwide and shows various clinical manifestations. It is a genetic disorder characterized by a specific and a recognizable pattern of anomalies. The major clinical features are ocular coloboma, heart malformations, atresia of the choanae, growth retardation, genital hypoplasia, and ear abnormalities. The chromodomain helicase DNA-binding protein 7 (CHD7) gene, located on chromosome 8q12.1, causes CHARGE syndrome. The CHD7 protein is an adenosine triphosphate (ATP)-dependent chromatin remodeling protein. A total of 67% of patients clinically diagnosed with CHARGE syndrome have CHD7 mutations. Five hundred twenty-eight pathogenic and unique CHD7 alterations have been identified so far. We describe a patient with a CHARGE syndrome diagnosis who carried a novel de novo mutation, a c.3896T>C (p. leu1299Pro) missense mutation, in the CHD7 gene. This finding will provide more information for genetic counseling and expand our understanding of the pathogenesis and development of CHARGE syndrome.

Abstract LB-168: A pilot clinical trial of chromodomain-helicase-DNA-binding protein 7 (CHD7) expression as a prognostic and predictive biomarker in patients with early-stage pancreatic adenocarcinoma.

Abstract Background/ Objectives Chromodomain helicase DNA Binding protein 7 (CHD7) modulates chromatin remodeling during genome maintenance. Its role in pancreatic cancer (PAC) is unestablished, but preliminary data for Gemcitabine (GEM) sensitivity in pancreatic cell lines and pilot clinical data is promising. This study will evaluate CHD7 as a prognostic and predictive factor in resected PAC using 1) immunohistochemistry (IHC) of patient samples from RTOG 97-04, 2) prospective evaluation of CHD7 over-expression and treatment response in patients receiving FOLFIRINOX and GEM-based chemoradiotherapy (CRT) for locally advanced PAC at our institution and 3) a Phase II molecular-driven randomized trial of personalized therapy based on CHD7 expression. Methodology A loss of function siRNA screen identified genes, including CHD7, that conferred GEM sensitivity when silenced using GEM-treated Mia PaCa-2 cells. CHD7 expression was assessed by IHC scoring in 80 patients who underwent curative intent resection of PAC between 1/2000 and 10/2008. Kaplan-meier survival analysis was performed for recurrence-free survival (RFS) and overall survival (OS). Univariate (UV) and Multivariate (MV) Cox regression analyses using clinically relevant covariates were used to correlate CHD7 expression levels with RFS and OS in patients receiving GEM therapy (n=42). This analysis will be validated in 200 patient samples from RTOG 97-04. CHD7 expression will be correlated with RFS and OS in GEM and 5-Fluorouracil (5-FU) treatment arms. CHD7 expression will also be measured in pre-chemotherapy core biopsies from locally advanced PAC patients treated at our institution. Patients will receive either two cycles of FOLFIRINOX (FOL) followed by GEM-based CRT at a dose of 1000mg/m2 once weekly or two cycles of FOL followed by Capecitabine (CAP)-based CRT. CHD7 expression will again be correlated with survival. These results will be followed by an ECOG- sponsored multi-institutional Phase II randomized trial of FOL and GEM-based CRT or FOL and CAP-based CRT based on CHD7 gene expression. Preliminary Data/ Anticipated Results In patients receiving GEM (n=42), high CHD7 was associated with poor RFS (7 months vs 15 months; p=.025) and poor OS (10 months vs 18 months; p=.015). On MV analysis, high CHD7 expression remained a predictor of poor RFS (HR 8.2 [95% CI 2.4-28]; p=.001) and poor OS (HR 11.6 [95% CI 3.4-40); p<.0001). In the subset of patients receiving adjuvant therapy without GEM (n=17), CHD7 was not associated with RFS (p=0.1) or OS (p=0.4). We expect our RTOG 97-04 validation study to demonstrate stronger correlation of low CHD7 expression with improved RFS and OS in GEM-treated patients. Similarly, we expect our institutional trial to demonstrate improved RFS and OS with low CHD7 in the GEM-treated arm. Citation Format: Lauren E. Colbert, William A. Hall, Claire W. Hardy, Sarah B. Fisher, David S. Yu, Shishir K. Maithel, Bassel El-Rayes, Burcu Saka, N Volkan Adsay, Aleksandra Petrova, Brooke Pantazides, Jeanne Kowalski, Khanjan Gandhi, David Kooby, Charles Staley, Jerome C. Landry. A pilot clinical trial of chromodomain-helicase-DNA-binding protein 7 (CHD7) expression as a prognostic and predictive biomarker in patients with early-stage pancreatic adenocarcinoma. [abstract]. In: Proceedings of the 104th Annual Meeting of the American Association for Cancer Research; 2013 Apr 6-10; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2013;73(8 Suppl):Abstract nr LB-168. doi:10.1158/1538-7445.AM2013-LB-168

Complete Screening of 50 Patients with CHARGE Syndrome for Anomalies in the CHD7 Gene Using a Denaturing High-Performance Liquid Chromatography–Based Protocol : New Guidelines and a Proposal for Routine Diagnosis

Ocular coloboma, heart malformation, choanal atresia, retardation of growth and/or development, genital hypoplasia, and ear anomalies associated with deafness (CHARGE) syndrome is a rare, usually sporadic, autosomal dominant disorder, caused by mutations within the CHD7 (chromodomain helicase DNA-binding protein 7) gene, in nearly 70% of cases. Because human CHD7 is relatively large (38 exons encoding a 300-kDa protein), genetic analysis requires cost-effective and time-consuming techniques. Herein, we propose an alternative screening method to quickly detect CHD7 mutations using mainly denaturing high-performance liquid chromatography. The entire coding region with exon-intron boundaries was amplified under the same experimental conditions. Each amplicon of the same CHD7 region was subjected to denaturing high-performance liquid chromatography analysis, and resulting chromatograms were compared within small series of patients. Because a CHD7 mutation differs generally from one patient to another, corresponding chromatograms exhibited a unique pattern that is significantly different from common polymorphisms. Only amplicons exhibiting a unique profile were subjected to DNA sequencing analysis. Intragenic rearrangements were investigated with only nine multiplex PCRs. In conclusion, using our protocol, we can quickly detect the right containing mutation amplicon and we provide a robust, rapid, and cheaper method to screen CHD7 microrearrangements or an entire deletion.

Cloning and characterization of a novel alternatively spliced transcript of the human CHD7 putative helicase

BackgroundThe CHD7 (Chromodomain Helicase DNA binding protein 7) gene encodes a member of the chromodomain family of ATP-dependent chromatin remodeling enzymes. Mutations in the CHD7 gene are found in individuals with CHARGE, a syndrome characterized by multiple birth malformations in several tissues. CHD7 was identified as a binding partner of PBAF complex (Polybromo and BRG Associated Factor containing complex) playing a central role in the transcriptional reprogramming process associated to the formation of multipotent migratory neural crest, a transient cell population associated with the genesis of various tissues. CHD7 is a large gene containing 38 annotated exons and spanning 200 kb of genomic sequence. Although genes containing such number of exons are expected to have several alternative transcripts, there are very few evidences of alternative transcripts associated to CHD7 to date indicating that alternative splicing associated to this gene is poorly characterized.FindingsHere, we report the cloning and characterization by experimental and computational studies of a novel alternative transcript of the human CHD7 (named CHD7 CRA_e), which lacks most of its coding exons. We confirmed by overexpression of CHD7 CRA_e alternative transcript that it is translated into a protein isoform lacking most of the domains displayed by the canonical isoform. Expression of the CHD7 CRA_e transcript was detected in normal liver, in addition to the DU145 human prostate carcinoma cell line from which it was originally isolated.ConclusionsOur findings indicate that the splicing event associated to the CHD7 CRA_e alternative transcript is functional. The characterization of the CHD7 CRA_e novel isoform presented here not only sets the basis for more detailed functional studies of this isoform, but, also, contributes to the alternative splicing annotation of the CHD7 gene and the design of future functional studies aimed at the elucidation of the molecular functions of its gene products.

CHARGE syndrome as unusual cause of hypogonadism: endocrine and molecular evaluation

Coloboma, heart defect, atresia choanae, retarded growth and development, genital hypoplasia, ear anomalies (CHARGE) syndrome is a genetic syndrome in which hypogonadism is a frequent feature. A causative mutation within the chromodomain helicase DNA-binding protein-7 gene, which plays an important role in the embryonic development, is present in 2/3 of affected patients. We describe the clinical, hormonal and molecular characteristics of a young man from Ecuador who was diagnosed as having CHARGE syndrome at an adult age. The patient showed several phenotypic features of the syndrome, associated with a prepubertal state and cryptorchidism; hypogonadotrophic hypogonadism with undetectable testosterone levels not responsive to hCG testing and severe osteoporosis were ascertained. Molecular evaluation of the CHD7 gene showed the novel frameshift truncating heterozygous mutation p.Tyr1046Glyfs*23 in exon 12. Magnetic resonance imaging revealed mild hypoplasia of the pituitary gland and hypoplasia of the posterior cranial fossa. Parenteral testosterone therapy led to sexual development over time and, in combination with diphophonate therapy and calcium-vitamin D supplementation, significantly improved bone mineralisation. Early proper hormonal treatment of hypogonadism in patients with complex genetic syndromes is important to achieve normal sexual maturation, improve quality of life and avoid significant comorbidities, such as osteoporosis.

Screening for CHARGE Syndrome Mutations in the CHD7 Gene Using Denaturing High-Performance Liquid Chromatography

Mutations in the CHD7 (chromodomain helicase DNA binding protein 7) gene cause CHARGE syndrome. At present, however, genetic testing of the CHD7 gene is not commonly applied in clinical settings because the currently available assays are technically and financially demanding, mainly because of the size of the gene. In the present study, we optimized the highly sensitive and specific mutation scanning method automated denaturing high-performance liquid chromatography (DHPLC) to analyze the entire coding region of CHD7. The coding region was amplified by 39 primer pairs, all of which have the same cycling conditions, aliquoted on a 96-well format polymerase chain reaction (PCR) plate. In this manner, all of the exons were amplified simultaneously using a single block in a thermal cycler. We then wrote a computer script to analyze each segment of the CHD7 gene by DHPLC in a serial manner using conditions that were optimized for each amplicon. The implementation of this screening method for CHD7 will help medical geneticists confirm their clinical impressions and provide accurate genetic counseling to the patients with CHARGE syndrome and their families.