Deafness_Isolated
Gene: CPD
CPD encodes carboxypeptidase D which is part of the metallocarboxylpeptidases family. These enzymes are zinc dependent and cleave c terminal arginine and lysine. Which in turn has a role in production of nitric oxide which is known to play role in the cochlea.
PMID: 41026541 describes 5 individuals from 3 families with biallelic missense variants in CPD who have prelingual onset bilateral profound SNHL. No syndromic features were noted in affected probands.
All variants appropriately rare in gnomad v4 for a rare recessive disorder.
No homozygous loss of function variants in gene in gnomad v4.
All families consanguineous
Functional studies demonstrated reduction in nitric oxide levels in patient cells as well as increased apoptosis with rescue upon introduction on L arginine. Proposed mechanism of disease is loss of function.
Drosophila studies demonstrated disrupted Johnston’s organ morphology and impaired auditory transduction with partial rescue by arginine. Other supportive functional models discussed in paper.
Authors suggest potential treatment of affected individuals with arginine supplementation.
Sources: LiteratureCreated: 6 Oct 2025, 4:20 a.m. | Last Modified: 6 Oct 2025, 4:26 a.m.
Panel Version: 1.74
Mode of inheritance
BIALLELIC, autosomal or pseudoautosomal
Phenotypes
Nonsyndromic genetic hearing loss, MONDO:0019497, CPD-related
Publications
Gene: cpd has been classified as Green List (High Evidence).
Gene: cpd has been classified as Green List (High Evidence).
gene: CPD was added gene: CPD was added to Deafness_Isolated. Sources: Literature Mode of inheritance for gene: CPD was set to BIALLELIC, autosomal or pseudoautosomal Publications for gene: CPD were set to PMID: 41026541 Phenotypes for gene: CPD were set to Nonsyndromic genetic hearing loss, MONDO:0019497, CPD-related Review for gene: CPD was set to GREEN