Chromodomain Helicase DNA-binding Protein 7 Mutations 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.

The chromatin remodelling factor Chd7 protects auditory neurons and sensory hair cells from stress-induced degeneration

Neurons and sensory cells are particularly vulnerable to oxidative stress due to their high oxygen demand during stimulus perception and transmission. The mechanisms that protect them from stress-induced death and degeneration remain elusive. Here we show that embryonic deletion of the chromodomain helicase DNA-binding protein 7 (CHD7) in auditory neurons or hair cells leads to sensorineural hearing loss due to postnatal degeneration of both cell types. Mechanistically, we demonstrate that CHD7 controls the expression of major stress pathway components. In its absence, hair cells are hypersensitive, dying rapidly after brief exposure to stress inducers, suggesting that sound at the onset of hearing triggers their degeneration. In humans, CHD7 haploinsufficiency causes CHARGE syndrome, a disorder affecting multiple organs including the ear. Our findings suggest that CHD7 mutations cause developmentally silent phenotypes that predispose cells to postnatal degeneration due to a failure of protective mechanisms.

Abstract #989420: A Novel CHD7 Mutation, Described as a Variant of Uncertain Significance, is Found in a Patient Diagnosed with Kallmann Syndrome

Reporting a novel mutation in chromodomain-helicase-DNA-binding protein 7 (CHD7) gene in the case of Kallmann syndrome, which has been classified as a Variant of Uncertain Significance.

A case of CHARGE syndrome associated with hyperinsulinemic hypoglycemia in infancy

CHARGE syndrome is a rare autosomal dominant disorder involving multiple organs. Chromodomain helicase DNA binding protein-7 (CHD7) is a major causative gene of CHARGE syndrome. We herein report a male infant born at full term with asphyxia who was diagnosed with CHARGE syndrome based on the typical anomalies. He showed a poor sucking ability and suffered from continuous hypoglycemia in early infancy, ultimately requiring tube feeding. While in a hypoglycemic status, inappropriate high insulin and low growth hormone levels were noticed. Growth hormone replacement therapy partially increased his blood glucose levels, but asymptomatic hypoglycemia with hyperinsulinemia was occasionally noticed. Additional diazoxide treatment stabilized his blood level to within the normal range. A genetic analysis of CHD7 showed the novel heterozygous monoallelic mutation c.2990delT causing a reading frameshift p.Leu997Trpfs*15 in exon 12. This case shows that patients with CHARGE syndrome caused by a CHD7 mutation may present with persistent hyperinsulinemic hypoglycemia, just like other dysmorphic syndromes genetically caused by aberrations in chromatin remodeling.

Cerebellar vermis hypoplasia in CHARGE syndrome: clinical and molecular characterization of 18 unrelated Korean patients.

CHARGE syndrome (OMIM 214800) is a rare autosomal-dominant congenital malformation syndrome that results from haploinsufficiency of the chromodomain helicase DNA-binding protein 7 (CHD7). We performed a phenotypic characterization and genetic analysis of CHD7 in 18 Korean patients with CHARGE syndrome. Eighteen unrelated Korean patients (10 females and 8 males; age range 0.0-19.6 years) with CHARGE syndrome were enrolled. Clinical data were collected by retrospective review of medical records. A serial analysis via sequencing and multiple ligation-dependent probe amplification of CHD7 was performed to determine the molecular genetic spectrum of the patients. The prevalence of cardinal symptoms was as follows: coloboma (13/18, 72.2%), heart defects (13/18, 72.2%), choanal atresia/stenosis (4/18, 22.2%), retarded growth (10/18, 55.6%), genital anomalies (15/18, 83.3%) and ear abnormalities (18/18, 100%). Five patients had cerebellar vermis hypoplasia (5/17, 29.4%) with no clinical symptoms or signs of cerebellar dysfunction. Furthermore, we identified genetic alterations in all 18 patients, including 10 novel mutations. Considering its frequency among patients with CHD7 mutations, cerebellar vermis hypoplasia may be a clinical diagnostic clue of CHARGE syndrome, although it is not included in the diagnostic criteria. And, the identification of CHD7 mutations may help the confirmative diagnosis.

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.

Phenotype in 18 Danish subjects with genetically verified CHARGE syndrome

CHARGE (coloboma of the eye, heart defects, choanal atresia, retarded growth and development, genital hypoplasia and ear anomalies and/or hearing loss) syndrome is a rare genetic, multiple-malformation syndrome. About 80% of patients with a clinical diagnose, have a mutation or a deletion in the gene encoding chromodomain helicase DNA-binding protein 7 (CHD7). Genotype-phenotype correlation is only partly known. In this nationwide study, phenotypic characteristics of 18 Danish CHD7 mutation positive CHARGE individuals (N = 18) are presented. We studied patient records, clinical photographs, computed tomography, and magnetic resonance imaging (MRI). Information was not available for all traits in all subjects. Therefore, the results are presented as fractions. The following prevalence of cardinal symptoms were found: coloboma, 16/17; heart defects, 14/18; choanal atresia, 7/17; retarded growth and development, 11/13; genital abnormalities, 5/18; ear anomalies, 15/17 and sensorineural hearing loss, 14/15. Vestibular dysfunction (10/13) and swallowing problems (12/15) were other frequent cranial nerve dysfunctions. Three-dimensional reconstructions of MRI scans showed temporal bone abnormalities in >85%. CHARGE syndrome present a broad phenotypic spectrum, although some clinical features are more frequently occurring than others. Here, we suggest that genetic testing for CHD7 mutation should be considered in neonates with a specific combination of several clinical symptoms.

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.

Terminal 4q deletion and 8q duplication in a patient with CHARGE-like features

The CHARGE syndrome is a multiple congenital malformation syndrome that usually results from deletion or heterozygous loss of function mutations of the chromodomain helicase DNA-binding protein 7 ( CHD7) gene at 8q12.1. Besides CHD7-related cases, some patients with CHARGE-like phenotype have been reported with chromosomal imbalances. We describe a patient with a pattern of malformations reminiscent of CHARGE syndrome: choanal atresia, facial dysmorphism (micrognathia, hypertelorism, epicanthic folds, and depressed, broad nasal bridge), cardiovascular malformations, cryptorchidism, and developmental delay. He had duplication 8q and deletion 4q derived from paternal translocation t(4;8)(q34;q22.1). CHD7 mutation or deletion was excluded. The present report to the best of our knowledge is the only one describing an unbalanced translocation t(4;8) and CHARGE-like phenotype.

Anosmia Predicts Hypogonadotropic Hypogonadism in CHARGE Syndrome

To test the hypothesis that a smell test could predict the occurrence of hypogonadotropic hypogonadism (HH) in patients with CHARGE syndrome, which is a variable combination of ocular coloboma, heart defects, choanal atresia, retardation of growth/development, genital hypoplasia, and ear anomalies or hearing loss caused by mutations in the CHD7 (chromodomain helicase DNA binding protein 7) gene. We performed endocrine studies and smell testing (University of Pennsylvania Smell Identification Test) in 35 adolescent patients with molecularly confirmed CHARGE syndrome. Complete data on smell and puberty were available for 15 patients; 11 patients had both anosmia and HH, whereas 4 patients had normosmia/hyposmia and spontaneous puberty. In addition, 7 boys were highly suspected of having HH (they were too young for definite HH diagnosis, but all had cryptorchidism, micropenis, or both) and had anosmia. The type of CHD7 mutation could not predict HH because a father and daughter with the same CHD7 mutation were discordant for HH and anosmia. Anosmia and HH were highly correlated in our cohort, and therefore smell testing seems to be an attractive method for predicting the occurrence of HH in patients with CHARGE syndrome. The use of this test could prevent delay of hormonal pubertal induction, resulting in an age-appropriate puberty.

Novel CHD7 mutations contributing to the mutation spectrum in patients with CHARGE syndrome

CHARGE syndrome is an autosomal dominant inherited multiple malformation disorder typically characterized by coloboma, choanal atresia, hypoplastic semicircular canal, cranial nerve defects, cardiovascular malformations and ear abnormalities. Mutations in the chromodomain helicase DNA-binding protein 7 ( CHD7) gene are the major cause of CHARGE syndrome. Mutation analysis was performed in 18 patients with firm or tentative clinical diagnosis of CHARGE syndrome. In this study eight mutations distributed across the gene were found. Five novel mutations – one missense (c.2936T > C), one nonsense (c.8093C > A) and three frameshift mutations (c.804_805insAT, c.1757_1770del14, c.1793delA) – were identified. As far as familial data were available these mutations were found to have arisen de novo. Comparison of the clinical features of patients with the same mutation demonstrates that expression of the phenotype is highly variable. The mutation detection rate in this study was 44.4% in patients with a clinically established or suspected diagnosis of CHARGE syndrome.

Histology and synchrotron radiation‐based microtomography of the inner ear in a molecularly confirmed case of CHARGE syndrome

CHARGE (Coloboma of the iris or retina, heart defects, atresia of the choanae, retardation of growth and/or development, genital anomalies, ear anomalies) syndrome (OMIM #214800) affects about 1 in 10,000 children and is most often caused by chromodomain helicase DNA-binding protein-7 (CHD7) mutations. Inner ear defects and vestibular abnormalities are particularly common. Specifically, semicircular canal (SCC) hypoplasia/aplasia and the presence of a Mondini malformation can be considered pathognomonic in the context of congenital malformations of the CHARGE syndrome. We obtained a temporal bone (TB) of a patient with CHARGE syndrome who died from bacteremia at 3 months of age. The clinical diagnosis was confirmed in the patient by direct DNA sequencing and the detection of a de novo, truncating CHD7 mutation, c.6169dup (p.R2057fs). We assessed changes of the TB and the degree of neural preservation, which may influence the potential benefit of cochlear implantation. The TB was analyzed using synchrotron radiation-based micro computed tomography, and by light microscopy. The vestibular partition consisted of a rudimentary vestibule with agenesis of the SCCs. The cochlea was hypoplastic with poor or deficient interscaling and shortened (Mondini dysplasia). The organ of Corti had near normal structure and innervation. Modiolus and Rosenthal's canal were hypoplastic with perikarya displaced along the axon bundles into the internal acoustic meatus, which may be explained by the arrest or limited migration and translocation of the cell nuclei into the cochlear tube during development.

CHD7 mutation spectrum in 28 Swedish patients diagnosed with CHARGE syndrome

CHARGE syndrome is a disorder characterized by Coloboma, Heart defect, Atresia choanae, Retarded growth and/or development, Genital hypoplasia and Ear anomalies. Heterozygous mutations in the chromodomain helicase DNA-binding protein 7 (CHD7) gene have been identified in about 60% of individuals diagnosed with CHARGE syndrome. We performed a CHD7 mutation screening by direct exon sequencing in 28 index patients (26 sporadic cases, 1 familial case consisting of a brother and sister and 1 case consisting of monozygotic twins) diagnosed with CHARGE syndrome in order to determine the mutations in a cohort of Swedish CHARGE syndrome patients. The patients without a detectable CHD7 mutation, or with a missense mutation, were further investigated by multiplex ligation-dependent probe amplification (MLPA) in order to search for intragenic deletions or duplications. Thirteen novel mutations and five previously reported mutations were detected. The mutations were scattered throughout the gene and included nonsense, frameshift and missense mutations as well as intragenic deletions. In conclusion, CHD7 mutations were detected in a large proportion (64%) of cases diagnosed with CHARGE syndrome. Screening for intragenic deletions with MLPA is recommended in cases where mutations are not found by sequencing. In addition, a CDH7 mutation was found in an individual without temporal bone malformation.