The rs267606619 T allele (also known as the 1494T allele) is assigned as a MT-RNR1 increased risk of aminoglycoside-induced hearing loss allele by CPIC. Patients with the T allele may have an increased risk of experiencing hearing loss when treated with streptomycin as compared to patients with the 1494C allele. However, conflicting evidence has been reported. Almost all individuals studied were homoplasmic for the T allele; it is unclear how heteroplasmy affects the severity or occurrence of aminoglycoside-induced hearing loss. MT-RNR1 is a mitochondrial gene and is inherited as a haploid (i.e. there is only ever one allele present). Other genetic and clinical factors may also influence risk of hearing loss when treated with streptomycin.