Table 2.

Summary of Molecular Genetic Testing Used in Branchiootorenal Spectrum Disorders (BOR/BOS)

Gene 1% of All BOR/BOSTest MethodMutations Detected 2
EYA140%Mutation scanningSmall insertions, small deletions, missense and nonsense mutations
Duplication/deletion analysis 3Partial- or whole-gene rearrangements 4
SIX52.5%Sequence analysis 5Sequence variants 6
SIX12%Sequence analysis 5Sequence variants 7

See Table A. Genes and Databases for chromosome locus and protein name.


See Molecular Genetics for information on allelic variants.


Testing that identifies deletions/duplications not readily detectable by sequence analysis of the coding and flanking intronic regions of genomic DNA; included in the variety of methods that may be used are: quantitative PCR, long-range PCR, multiplex ligation-dependent probe amplification (MLPA), and chromosomal microarray (CMA) that includes this gene/chromosome segment.


In approximately 10% of individuals with BOR/BOS, a chromosomal rearrangement of the EYA1 region will be present [Chang et al 2004]. See Molecular Genetics.


Examples of mutations detected by sequence analysis may include small intragenic deletions/insertions and missense, nonsense, and splice site mutations; typically, exonic or whole-gene deletions/duplications are not detected. For issues to consider in interpretation of sequence analysis results, click here.


Heterozygous mutations were identified in 5/95 (5.2%) unrelated individuals with BOR syndrome in whom an EYA1 or SIX1 mutation was not identified [Hoskins et al 2007]; these data imply a SIX5 mutation rate of fewer than 2.5% of persons with BOR syndrome.


Heterozygous mutations were identified in 10/247 (4.0%) unrelated individuals with BOR syndrome in whom an EYA1 or SIX5 mutation was not identified [Kochhar et al 2008]. This prevalence implies that SIX1 mutations account for approximately 2% of cases of BOR syndrome.

From: Branchiootorenal Spectrum Disorders

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