A novel SOX10 mutation causing Waardenburg syndrome type 2 by expressing a truncated and dysfunctional protein in a Chinese child

This study aimed to identify the causative variants in a patient with Waardenburg syndrome (WS) type 2 using whole exome sequencing (WES).

The clinical features of the patient were collected. WES was performed on the patient and his parents to screen causative genetic variants and Sanger sequencing was performed to validate the candidate mutation. The AlphaFold2 software was used to predict the changes in the 3D structure of the mutant protein. Western blotting and immunocytochemistry were used to determine the SOX10 mutant in vitro.

A de novo variant of SOX10 gene, NM_006941.4: c.707_714del (p. H236Pfs*42), was identified, and it was predicted to disrupt the wild-type DIM/HMG conformation in SOX10. In-vitro analysis showed an increased level of expression of the mutant compared to the wild-type.

Our findings helped to understand the genotype-phenotype association in WS2 cases with SOX10 mutations.