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Keywords:

  • EYA1;
  • SIX1;
  • SIX5;
  • branchio-oto-renal syndrome;
  • hearing loss;
  • Level of Evidence: 1b

Abstract

Objectives/Hypothesis:

To explore the genetic characteristics of branchio-oto-renal (BOR) syndrome in an East Asian population.

Study Design:

Prospective clinical genetic study.

Methods:

Twelve families (total of 18 patients) who fulfilled the criteria for BOR syndrome were enrolled in this study. Mutation screening of the EYA1, SIX1, and SIX5 genes was performed by direct sequencing and quantitative polymerase chain reaction, and genotype-phenotype correlation was investigated.

Results:

Two novel EYA1 variants, c.466C>T (p.Q156X) and c.1735delG (p.D579fs), were identified in two multiplex families. The c.466C>T variant resulted in a truncated EYA1 protein, whereas the c.1735delG variant was predicted to encode an EYA1 protein with an abnormal C terminal. Neither variant was identified in a panel of 100 normal controls, and both were cosegregated with the BOR phenotype in the pedigrees, indicating that they were pathogenic mutations. No SIX1 and SIX5 mutations were detected in members of the remaining 10 families. Analysis of the genotype-phenotype correlation revealed a high phenotypic variability between and within BOR families.

Conclusions:

Two novel EYA1 mutations (c.466C>T and c.1735delG) were identified in two families with BOR syndrome. SIX1 and SIX5 mutations were not detected in the present study. Further investigation is warranted regarding the contribution of SIX1 and SIX5 mutations to BOR syndrome in East Asian populations.