PRPS1 and X-linked hereditary sensory and autonomic neuropathy with deafness: There were two deafness genes on Xq22.3; COL4A5 which is implicated in Alport syndrome with variable sensorineural hearing loss [Barker et al., 1990] and PRPS1 which is mutated in non-syndromic X-linked deafness-1 [Liu et al., 2010].