In a prior study carried out in a sample of the Brazilian population, mutations to the GJB2 gene were found in 22% of the families with non-syndromical sensorineural hearing loss, once again pointing out that molecular analysis of this gene in patients with non-syndromical hearing loss should be the first step in determining hearing loss causes in our country (Oliveira et al., 2001). The gene discussed is GJB2; the disease is sensorineural hearing loss disorder.