Functional characterization of a novel loss-of-function mutation of PRPS1 related to early-onset progressive nonsyndromic hearing loss in Koreans (DFNX1): Potential implications on future therapeutic intervention.

Abstract

BACKGROUND:

The symptoms of phosphoribosyl pyrophosphate synthetase 1 (PRPS1) deficiency diseases have been reported to be alleviated by medication. In the present study, we report biochemical data that favor PRPS1 deficiency-related hearing loss as a potential target for pharmaceutical treatment.

METHODS:

We recruited 42 probands from subjects aged less than 15 years with a moderate degree of nonsyndromic autosomal-recessive or sporadic sensorineural hearing loss (SNHL) in at least one side. Molecular genetic testing, including targeted exome sequencing (TES) of 129 genes for deafness, and in silico prediction were performed.

RESULTS:

A strong candidate variant (p.A82P) of PRPS1 is co-segregated with SNHL in X-linked recessive inheritance from one Korean multiplex SNHL family. Subsequent measurement of in vitro enzymatic activities of PRPS1 from erythrocytes of affected and unaffected family members, as well as unrelated normal controls, confirmed a pathogenic role of this variant. In detail, compared to normal hearing controls (0.23-0.26 nmol/ml/h), the proband, the affected sibling and their normal hearing mother demonstrated a significantly decreased PRPS1 enzymatic activity (0.07, 0.03 and 0.11 nmol/ml/h, respectively). This novel loss-of-function mutation of PRPS1 (p.A82P) is the ninth and sixth most reported mutation in the world and in Asia, respectively.

CONCLUSIONS:

DFNX1 was found to account for approximately 2.4% (1/42) of moderate SNHL in a Korean pediatric population. Confirmation of PRPS1 activity deficiency and an audiologic phenotype that initially begins in a milder form of SNHL, as in our family, should indicate the need for rigorous genetic screening as early as possible.

• Authors: So Young Kim, Ah Reum Kim, Nayoung K D Kim, Chung Lee, Jin Hee Han, Min Young Kim, Eun-Hee Jeon, Woong-Yang Park, Rahul Mittal, Denise Yan, Xue Zhong Liu, Byung Yoon Choi
• Journal: The journal of gene medicine (J Gene Med) Vol. 18 Issue 11-12 Pg. 353-358 (Nov 2016) ISSN: 1521-2254 [Electronic] England
• PMID: 27886419 (Publication Type: Journal Article)
• Copyright: Copyright © 2016 John Wiley & Sons, Ltd.

Chemical References

• PRPS1 protein, human
• Ribose-Phosphate Pyrophosphokinase

Topics

• Base Sequence
• Case-Control Studies
• Child
• Child, Preschool
• DNA Mutational Analysis
• Deafness (genetics)
• Female
• Genetic Association Studies
• Genetic Diseases, X-Linked (genetics)
• Genetic Predisposition to Disease
• Hearing Loss, Sensorineural (genetics)
• Humans
• Male
• Mutation
• Pedigree
• Republic of Korea
• Ribose-Phosphate Pyrophosphokinase (genetics)
• Exome Sequencing