BACKGROUND: X-linked Charcot-Marie-Tooth disease type 5 (CMTX5) is caused by 
mutations in the gene encoding phosphoribosyl pyrophosphate synthetase I 
(PRPS1). There has been only one case report of CMTX5 patients. The aim of this 
study was to identify the causative gene in a family with CMTX with peripheral 
neuropathy and deafness.
CASE REPORT: A Korean family with X-linked recessive CMT was enrolled. The age 
at the onset of hearing loss of the male proband was 5 months, and that of 
steppage gait was 6 years; he underwent cochlear surgery at the age of 12 years. 
In contrast to what was reported for the first patients with CMTX5, this patient 
did not exhibit optic atrophy. Furthermore, there was no cognitive impairment, 
respiratory dysfunction, or visual disturbance. Assessment of his family history 
revealed two male relatives with very similar clinical manifestations. 
Electrophysiological evaluations disclosed sensorineural hearing loss and 
peripheral neuropathy. Whole-exome sequencing identified a novel p.Ala121Gly 
(c.362C>G) PRPS1 mutation as the underlying genetic cause of the clinical 
phenotype.
CONCLUSIONS: A novel mutation of PRPS1 was identified in a CMTX5 family in which 
the proband had a phenotype of peripheral neuropathy with early-onset hearing 
loss, but no optic atrophy. The findings of this study will expand the clinical 
spectrum of X-linked recessive CMT and will be useful for the molecular 
diagnosis of clinically heterogeneous peripheral neuropathies.