KIAA1199 was originally discovered as a deafness gene and was subsequently found to play a central role in degrading high-molecular-weight HA in the chondrocytes through rapid vesicle endocytosis and recycling, whereas HYAL1/2 and CD44 knockdown could not alter the ability of chondrocytes to degrade high-molecular-weight HA [17]. This evidence concerns the gene CD44 and deafness.