title: CHD7 mutational analysis and clinical considerations for auditory rehabilitation in deaf patients with CHARGE syndrome.
abstract: BACKGROUND
  Otologic manifestations are one of the most consistent findings of CHARGE syndrome found in more than 90%. Since genetic analysis of the CHD7 gene has rarely been performed in previous reports dealing with ear abnormalities, the genotypic spectrum of CHD7 mutations was analyzed in deaf patients with CHARGE syndrome, and the clinical considerations concerning auditory rehabilitation were investigated.
  
  
  METHODS
  Nine Korean patients with CHARGE syndrome showing profound hearing loss and semicircular canal aplasia were included. All 38 exons of CHD7 were analyzed by direct sequencing. For splice site variations, in silico and exon-trapping analyses were performed to verify the pathogenicity of nucleotide variations. Clinical features and the outcome of auditory rehabilitation were also analyzed.
  
  
  RESULTS
  Eight of 9 patients revealed alterations of the CHD7 gene including 3 frameshift, 2 nonsense, 2 splice site, and 1 missense mutations. Five of 9 patients were clinically diagnosed as atypical CHARGE syndrome but demonstrated various mutations of the CHD7 gene. One familial case showed intra-familial variability. Radiologic findings suggesting cochleovestibular nerve deficiency were identified in most of the patients. Of the 8 patients who underwent cochlear implantation, 5 patients demonstrated favorable outcome. Larger diameter of the cochleovestibular nerve on imaging and absence of severe mental retardation were factors related to better outcome after cochlear implantation rather than the type of CHD7 mutations. Auditory brainstem implantation was performed in two patients who did not benefit from cochlear implantation.
  
  
  CONCLUSIONS
  Genetic analysis of the CHD7 gene should be performed in cases with semicircular canal aplasia even when other typical features of CHARGE syndrome are absent. For auditory rehabilitation in CHARGE syndrome, cochlear implantation should be strongly recommended in selected cases with favorable prognostic factors. Auditory brainstem implantation may be a viable option in patients with CHARGE syndrome who have failed to benefit from cochlear implantation.
authors.affiliation: Department of Otorhinolaryngology, Kwandong University College of Medicine, Goyang, South Korea.
authors.forename: Mee Hyun
authors.initials: MH
authors.lastname: Song
authors.forename: Hyun-Ju
authors.initials: HJ
authors.lastname: Cho
authors.forename: Hee Keun
authors.initials: HK
authors.lastname: Lee
authors.forename: Tae Jun
authors.initials: TJ
authors.lastname: Kwon
authors.forename: Won-Sang
authors.initials: WS
authors.lastname: Lee
authors.forename: Sanghee
authors.initials: S
authors.lastname: Oh
authors.forename: Jinwoong
authors.initials: J
authors.lastname: Bok
authors.forename: Jae Young
authors.initials: JY
authors.lastname: Choi
authors.forename: Un-Kyung
authors.initials: UK
authors.lastname: Kim
mesh_terms: D000293:Adolescent; D000328:Adult; D038263:Auditory Brain Stem Implantation / Q000379:methods; D058747:CHARGE Syndrome / Q000235:genetics*; D002648:Child; D002675:Child, Preschool; D003051:Cochlea / Q000002:abnormalities; D019929:Cochlear Implantation / Q000379:methods; D018389:Codon, Nonsense; D004265:DNA Helicases / Q000235:genetics*; D004252:DNA Mutational Analysis; D004268:DNA-Binding Proteins / Q000235:genetics*; D003638:Deafness / Q000235:genetics* / Q000534:rehabilitation; D005192:Family Health; D005260:Female; D016368:Frameshift Mutation; D014644:Genetic Variation; D006801:Humans; D007223:Infant; D008297:Male; D020125:Mutation, Missense; D014725:Vestibular Nerve / Q000002:abnormalities
chemical_list: D018389:Codon, Nonsense; D004268:DNA-Binding Proteins; D004265:DNA Helicases; C491434:CHD7 protein, human