Using this method, the DFNM1 locus, a modifier of DFNB26-linked deafness was identified [3] and the deafness phenotype associated with the 1555A>G mutation in MTRNR1 was shown to be modified by three different genes: MTO1, TFB1M and GTPBP3 [51,52]. Here, GTPBP3 is linked to deafness.