For example, connexin 26 KO is lethal in mice, whereas a seemingly equivalent homozygous gene loss in humans (35delG, causes a frameshift with premature termination of the protein at the twelfth amino acid) is not lethal and results in non-syndromic hearing loss (DFNB1) [32,33]. The gene discussed is GJB2; the disease is autosomal recessive nonsyndromic hearing loss 1A.