A novel frameshift mutation of CHD7 in a Japanese patient with CHARGE syndrome

Whole-exome sequencing reveals genetic variants that may play a role in neurocytomas

OBJECTIVES

Neurocytomas (NCs) are rare intracranial tumors that can often be surgically resected. However, disease course is unpredictable in many patients and medical therapies are lacking. We have used whole exome sequencing to explore the molecular etiology for neurocytoma and assist in target identification to develop novel therapeutic interventions.

METHODS

We used whole exome sequencing (WES) to compare the molecular landscape of 21 primary & recurrent NCs to five normal cerebellar control samples. WES data was analyzed using the Qiagen Clinical Insight program, variants of interest (VOI) were interrogated using ConSurf, ScoreCons, & Ingenuity Pathway Analysis Software to predict their potential functional effects, and Copy number variations (CNVs) in the genes of interest were analyzed by Genewiz (Azenta Life Sciences).

RESULTS

Of 40 VOI involving thirty-six genes, 7 were pathogenic, 17 likely-pathogenic, and 16 of uncertain-significance. Of seven pathogenic NC associated variants, Glucosylceramidase beta 1 [GBA1 c.703T > C (p.S235P)] was mutated in 5/21 (24%), Coagulation factor VIII [F8 c.3637dupA (p.I1213fs*28)] in 4/21 (19%), Phenylalanine hydroxylase [PAH c.975C > A (p.Y325*)] in 3/21 (14%), and Fanconi anemia complementation group C [FANCC c.1162G > T (p.G388*)], Chromodomain helicase DNA binding protein 7 [CHD7 c.2839C > T (p.R947*)], Myosin VIIA [MYO7A c.940G > T (p.E314*)] and Dynein axonemal heavy chain 11 [DNAH11 c.3544C > T (p.R1182*)] in 2/21 (9.5%) NCs respectively. CNVs were noted in 85% of these latter 7 genes. Interestingly, a Carboxy-terminal domain RNA polymerase II polypeptide A small phosphatase 2 [CTDSP2 c.472G > A (p.E158K)] of uncertain significance was also found in > 70% of NC cases.

INTERPRETATION

The variants of interest we identified in the NCs regulate a variety of neurological processes including cilia motility, cell metabolism, immune responses, and DNA damage repair and provide novel insights into the molecular pathogenesis of these extremely rare tumors.

Next-generation sequencing for the diagnosis of patients with congenital multiple anomalies and / or intellectual disabilities

Background : In clinical practice, a large proportion of patients with multiple congenital anomalies and/or intellectual disabilities (MCA / ID) lacks a specific diagnosis. Recently, next-generation sequencing (NGS) has become an efficient strategy for genetic diagnosis of patients with MCA/ID.

OBJECTIVE

To review the utility of NGS for the diagnosis of patients with MCA / ID.

METHOD

Patients with MCA/ID were recruited between 2013 and 2017. Molecular diagnosis was performed using NGS-based targeted panel sequencing for 4,813 genes. Promising causative variants underwent confirmation by Sanger sequencing or chromosomal microarray.

RESULTS

Eighteen patients with MCA/ID were enrolled in this study. Of them, 8 cases (44%) were diagnosed by targeted panel sequencing. Most of diagnosed patients were able to receive better counseling and more appropriate medical management.

CONCLUSION

NGS-based targeted panel sequencing seems to be an effective testing strategy for diagnosis of patients with MCA/ID. J. Med. Invest. 67 : 246-249, August, 2020.

CHARGE syndrome associated with (I1460Rfs*15) frameshift mutation of CHD7 gene in a patient with arteria lusoria and horseshoe kidney

CHARGE syndrome is an autosomal dominant condition caused by mutations in the chromodomain helicase DNA binding protein 7 (CHD7) gene. The present study reported on the case of a 16-month-old female with plurimalformative syndrome, whose etiology was identified by clinical whole-exome sequencing (WES) analysis. Clinical and follow-up assessments identified multiple craniofacial dysmorphisms, congenital defects and functional symptoms, including dysphagia and Marcus Gunn jaw winking synkinesis. Trio-WES analysis was performed for the patient and their parents and the presence of CHARGE syndrome was further indicated using single-molecule real-time sequencing. A de novo pathogenic variant, c.4379_4380del (p.Ile1460Argfs^*15), was identified in exon 19 of the CHD7 gene, which resulted in a premature translational stop signal. Trio-WES analysis was used for further investigation, indicating that neither of the patient's parents had the mutation and confirming its de novo nature. To the best of our knowledge, the case of the present study was the first reported case of CHARGE syndrome in Romania with congenital defects including an aberrant right subclavian artery and a horseshoe kidney. CHARGE syndrome was diagnosed in the patient based on the pathogenic mutation in the CHD7 gene. To the best of our knowledge, the present case report is the first to suggest that the CHD7 gene variant is associated with CHARGE syndrome.

ALS and CHARGE syndrome: a clinical and genetic study

Amyotrophic Lateral Sclerosis and CHARGE syndrome are complex neurological disorders, which never occurred together in the same family and, to date, no putative correlation between them has been described on PubMed Central. Due to our aim was to evaluate the presence of different genetic variants involved in these pathologies, we reported a clinical and genetic description of two sisters affected by these two different disorders. In the CHARGE patient, molecular analysis of the CHD7 gene revealed the c.8016G >A de novo variant in exon 37. The ALS patient had been screened negative for mutations in SOD1, TARDBP, FUS/TLS, C9orf72 and KIF5A genes. Anyway, targeted next generation sequencing analysis identified known and unknown genetic variations in 39 ALS-related genes: a total of 380 variants were reported, of which 194 in the ALS patient and 186 in the CHARGE patient. To date, although the results suggest that the occurrence of the two syndromes in the same family is co-incidental rather than based on a causative genetic variant, we could hypothesize that other factors might act as modulators in the pathogenesis of these different phenotypes.

Atypical CHARGE associated with a novel frameshift mutation of CHD7 in a Chinese neonatal patient

BACKGROUND

CHARGE syndrome is an autosomal dominant malformation disorder caused by heterozygous loss of function mutations in the chromatin remodeler CHD7, which has been estimated to occur in 1:10,000 births worldwide. It is a genetic disorder closely resembles other pattern of anomalies. Genetic testing should be pointed out as a useful method for clinical diagnosis.

CASE PRESENTATION

A female infant was the second child born to a 33-year-old, gravida 3, para 2 mother. The infant was born at 37 + 4 weeks of gestation with a birth weight of 2440 g (- 1.1 S.D.). Clinical examination showed atypical CHARGE syndrome, with choanal atresia, a heart defect, and sensorineural deafness. Genomic DNA was extracted from peripheral venous blood sample using molecular biological technique. We used the Illumina TruSigt One sequencing panel on the MiSeq next- generation sequencing (NGS) platform for mutation screening and found a novel frameshift mutation in chromodomain helicase DNA binding protein 7 (CHD7; c.4656dupT). This mutation results in a new reading frame ending in p.(Ile1553fs). At the first month of age, the patient had a posterior nostril plasty operation by nasal endoscope. At the second month of age, she had patent ductus arteriosus ligation surgery. At the 4th month of age, she was discharged from the hospital.

CONCLUSIONS

Our findings further reveal that patients should not be rejected for CHD7 mutational analysis even if they do not fulfill CHARGE syndrome Verloes criteria.

Functional Analyses of a Novel Splice Variant in the CHD7 Gene, Found by Next Generation Sequencing, Confirm Its Pathogenicity in a Spanish Patient and Diagnose Him with CHARGE Syndrome

Mutations in CHD7 have been shown to be a major cause of CHARGE syndrome, which presents many symptoms and features common to other syndromes making its diagnosis difficult. Next generation sequencing (NGS) of a panel of intellectual disability related genes was performed in an adult patient without molecular diagnosis. A splice donor variant in CHD7 (c.5665 + 1G > T) was identified. To study its potential pathogenicity, exons and flanking intronic sequences were amplified from patient DNA and cloned into the pSAD^® splicing vector. HeLa cells were transfected with this construct and a wild-type minigene and functional analysis were performed. The construct with the c.5665 + 1G > T variant produced an aberrant transcript with an insert of 63 nucleotides of intron 28 creating a premature termination codon (TAG) 25 nucleotides downstream. This would lead to the insertion of 8 new amino acids and therefore a truncated 1896 amino acid protein. As a result of this, the patient was diagnosed with CHARGE syndrome. Functional analyses underline their usefulness for studying the pathogenicity of variants found by NGS and therefore its application to accurately diagnose patients.