The c.4000C>T variant in CDH23 is a missense variant predicted to cause substitution of arginine by tryptophan at amino acid 1334. The filtering allele frequency of this variant in gnomAD v4.1 is 0.03882%, and the minor allele frequency is 0.05343% in the Admixed American population (PM2_Supporting, BA1, and BS1 not met). The computational predictor REVEL gives a score of 0.316, which is neither above nor below the thresholds predicting a damaging or benign impact on CDH23 function (BP4 and PP3 not met). This variant has been reported in 2 probands with nonsyndromic hearing loss, however, the evidence did not support a causative role for the variant. The variant was also identified in a proband presenting with a range of cardiac and developmental clinical features; however the variant was absent in an affected parent, and these clinical features are not associated with CDH23. Additionally, the variant has been seen as a single heterozygous variant in 6 individuals undergoing testing for hearing loss in whom a second CDH23 variant was not identified. All of these individuals also had additional variants reported that were classified as either VUS, likely pathogenic, or pathogenic (PM3 not met; SCV000297305.2, SCV000205132.4, SCV001822517.3). In summary, this variant has been classified as a variant of uncertain significance for autosomal recessive Usher syndrome based on the ACMG/AMP criteria applied, as specified by the ClinGen Hearing Loss VCEP: No criteria met (ClinGen Hearing Loss VCEP specifications version 2; 7/16/2025).