The rs267606617 G allele (also known as the 1555G allele) is assigned as a MT-RNR1 increased risk of aminoglycoside-induced hearing loss allele by CPIC. Patients with the G allele may have an increased risk of experiencing aminoglycoside-induced hearing loss as compared to patients with the A allele. Most individuals studied were homoplasmic for the G 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 aminoglycoside-induced hearing loss.