The frequency of childhood deafness is estimated to be 1/500. Half of this hearing loss is genetic and approximately 80% of genetic hearing loss is nonsyndromic and inherited in an autosomal recessive manner. Approximately 50% of childhood nonsyndromic recessive hearing loss is caused by mutations in the connexin 26 (Cx26) gene (GJB2/DFNB1), making it the most common form of autosomal recessive nonsyndromic hearing loss with a carrier rate estimated to be as high as 1 in 36 (2.8%). Newborns with confirmed hearing loss should have Cx26 testing. Cx26 testing will help define a group in which approximately 60% will have profound or severe-profound hearing loss requiring aggressive language intervention.