The role of the apolipoprotein E (APOE) gene has also been suggested, known to be strongly associated with neurodegeneration: some studies have also evidenced an association between the apolipoprotein E e4 allele, which predisposes to Alzheimer’s disease, and hearing loss, although the data in this regard are still fragmented [63,64,65] and the specific molecular link between hearing loss and dementia remains unknown [66]. Here, APOE is linked to early-onset autosomal dominant Alzheimer disease.