GJB2 and deafness: To date, more than 100 GJB2 variants have been reported (see the Connexin‐deafness homepage: http://davinci.crg.es/deafness/), and there has been a general rule applied to the relationship between mutations and hearing loss; that inactivating mutations (deletion mutations and stop mutations) result in more severe phenotypes compared to those caused by non‐inactivating mutations (missense mutations) (Tsukada et al., 2010).