Genetic analysis of PAX3 for diagnosis of Waardenburg syndrome type I

Abstract

Conclusion: PAX3 genetic analysis increased the diagnostic accuracy for Waardenburg syndrome type I (WS1). Analysis of the three-dimensional (3D) structure of PAX3 helped verify the pathogenicity of a missense mutation, and multiple ligation-dependent probe amplification (MLPA) analysis of PAX3 increased the sensitivity of genetic diagnosis in patients with WS1. Objectives: Clinical diagnosis of WS1 is often difficult in individual patients with isolated, mild, or non-specific symptoms. The objective of the present study was to facilitate the accurate diagnosis of WS1 through genetic analysis of PAX3 and to expand the spectrum of known PAX3 mutations. Methods: In two Japanese families with WS1, we conducted a clinical evaluation of symptoms and genetic analysis, which involved direct sequencing, MLPA analysis, quantitative PCR of PAX3, and analysis of the predicted 3D structure of PAX3. The normal-hearing control group comprised 92 subjects who had normal hearing according to pure tone audiometry. Results: In one family, direct sequencing of PAX3 identified a heterozygous mutation, p.I59F. Analysis of PAX3 3D structures indicated that this mutation distorted the DNA-binding site of PAX3. In the other family, MLPA analysis and subsequent quantitative PCR detected a large, heterozygous deletion spanning 1759–2554 kb that eliminated 12–18 genes including a whole PAX3 gene.

Keywords::

• Mutation
• MLPA
• clinical diagnosis
• hearing loss
• dystopia canthorum
• pigmentary disorder

Acknowledgments

We thank the families that participated in this study. This study was supported by a Grant-in-Aid for Clinical Research from the National Hospital Organization, and by a Health and Labour Sciences Research Grants for Research on Rare and Intractable Diseases from the Ministry of Health, Labour and Welfare of Japan.

Declaration of interest: The authors report no conflicts of interest. The authors alone are responsible for the content and writing of the paper.