title: Expressivity of hearing loss in cases with Usher syndrome type IIA.
abstract: OBJECTIVE
  The purpose of this study was to compare the genotype/phenotype relationship between siblings with identical USH2A pathologic mutations and the consequent audiologic phenotypes, in particular degree of hearing loss (HL). Decade audiograms were also compared among two groups of affected subjects with different mutations of USH2A.
  
  
  METHODS
  DNA samples from patients with Usher syndrome type II were analysed. The audiological features of patients and affected siblings with USH2A mutations were also examined to identify genotype-phenotype correlations.
  
  
  METHODS
  Genetic and audiometric examinations were performed in 18 subjects from nine families with Usher syndrome type IIA.
  
  
  RESULTS
  Three different USH2A mutations were identified in the affected subjects. Both similarities and differences of the auditory phenotype were seen in families with several affected siblings. A variable degree of hearing loss, ranging from mild to profound, was observed among affected subjects. No significant differences in hearing thresholds were found the group of affected subjects with different pathological mutations.
  
  
  CONCLUSIONS
  Our results indicate that mutations in the USH2A gene and the resulting phenotype are probably modulated by other variables, such as modifying genes, epigenetics or environmental factors which may be of importance for better understanding the etiology of Usher syndrome.
authors.affiliation: * Department of Audiology, The Sahlgrenska Academy, Institute of Neuroscience and Physiology , Göteborg , Sweden.
authors.forename: André M
authors.initials: AM
authors.lastname: Sadeghi
authors.forename: Edward S
authors.initials: ES
authors.lastname: Cohn
authors.forename: William J
authors.initials: WJ
authors.lastname: Kimberling
authors.forename: Glenn
authors.initials: G
authors.lastname: Halvarsson
authors.forename: Claes
authors.initials: C
authors.lastname: Möller
mesh_terms: D000158:Acoustic Impedance Tests; D000293:Adolescent; D000328:Adult; D000368:Aged; D001301:Audiometry, Pure-Tone; D001309:Auditory Threshold; D002648:Child; D004252:DNA Mutational Analysis; D016326:Extracellular Matrix Proteins / Q000235:genetics; D005260:Female; D056726:Genetic Association Studies; D020022:Genetic Predisposition to Disease; D006309:Hearing / Q000235:genetics; D006801:Humans; D008297:Male; D008875:Middle Aged; D009154:Mutation; D009329:Nebraska; D010375:Pedigree; D010641:Phenotype; D012307:Risk Factors; D012720:Severity of Illness Index; D013548:Sweden; D052245:Usher Syndromes / Q000175:diagnosis / Q000235:genetics / Q000503:physiopathology*
chemical_list: D016326:Extracellular Matrix Proteins; C112735:USH2A protein, human