The cost-optimized DFNB1 testing strategy. The common mutation test lay in two reactions, a multiplex PCR with primer pairs for six deletions (c.35delG, c.313_326del14, c.235delC, c.167delT, c.358_360delGAG and GJB2-D13S175) and RLFP analysis of c.−23+1G>A, followed by gel-based fragment analysis to differentiate wild-type and mutation alleles.