Clinical manifestations and novel pathogenic variants in SOX10 in eight Danish probands with Waardenburg syndrome

Deciphering potential causative factors for undiagnosed Waardenburg syndrome through multi-data integration

BACKGROUND

Waardenburg syndrome (WS) is a rare genetic disorder mainly characterized by hearing loss and pigmentary abnormalities. Currently, seven causative genes have been identified for WS, but clinical genetic testing results show that 38.9% of WS patients remain molecularly unexplained. In this study, we performed multi-data integration analysis through protein-protein interaction and phenotype-similarity to comprehensively decipher the potential causative factors of undiagnosed WS. In addition, we explored the association between genotypes and phenotypes in WS with the manually collected 443 cases from published literature.

RESULTS

We predicted two possible WS pathogenic genes (KIT, CHD7) through multi-data integration analysis, which were further supported by gene expression profiles in single cells and phenotypes in gene knockout mouse. We also predicted twenty, seven, and five potential WS pathogenic variations in gene PAX3, MITF, and SOX10, respectively. Genotype-phenotype association analysis showed that white forelock and telecanthus were dominantly present in patients with PAX3 variants; skin freckles and premature graying of hair were more frequently observed in cases with MITF variants; while aganglionic megacolon and constipation occurred more often in those with SOX10 variants. Patients with variations of PAX3 and MITF were more likely to have synophrys and broad nasal root. Iris pigmentary abnormality was more common in patients with variations of PAX3 and SOX10. Moreover, we found that patients with variants of SOX10 had a higher risk of suffering from auditory system diseases and nervous system diseases, which were closely associated with the high expression abundance of SOX10 in ear tissues and brain tissues.

CONCLUSIONS

Our study provides new insights into the potential causative factors of WS and an alternative way to explore clinically undiagnosed cases, which will promote clinical diagnosis and genetic counseling. However, the two potential disease-causing genes (KIT, CHD7) and 32 potential pathogenic variants (PAX3: 20, MITF: 7, SOX10: 5) predicted by multi-data integration in this study are all computational predictions and need to be further verified through experiments in follow-up research.

Identification of a de novo, Novel Pathogenic Variant in the Splice Region of the SOX10 Gene in an Iranian Azeri Turkish Family with Waardenburg Syndrome

Background

Waardenburg syndrome (WS) is an inherited heterogeneous auditory pigmentary syndrome, divided into at least four types and characterized by iris heterochromia, white forelock, prominent nasal root, dystopia canthorum, middle eyebrow hypertrichosis, and deafness. Pathogenic variants in the SOX10 gene have been reported to be involved in WS disease.

Methods

Whole exome sequencing (WES) was conducted on a 24-year-old male, who originated from Iranian Azeri Turkish ethnic group, with symptoms of deafness and blue eyes from brown-eyed parents. Web-based tools including Mutation Taster, VarSome, SIFT, Human Splicing Finder (HSF), and I-TASSER, were used for bioinformatics analysis. To verify the WES findings, DNAs taken from the blood samples of all family members were subjected to PCR-Sanger sequencing.

Results

A novel heterozygous pathogenic variant, NC_000022.11 (NM_006941):c.428+1G>T, located in the second intron of the SOX10 gene and disrupting the splicing site, was identified in the proband. Sanger sequencing was applied on the proband and his parents. The results showed that the variant was a de novo pathogenic variant with an autosomal dominant inheritance pattern.

Conclusions

Identification of a novel de novo pathogenic variant, NC_000022.11 (NM_006941):c.428+1G>T, in the second intron of the SOX10 gene with autosomal dominant inheritance pattern.