A novel EYA1 splicing mutation in a Chinese branchio-oto syndrome family with functional analysis and reproductive intervention.

Abstract

Objectives: Branchio-oto syndrome (BOS) is a group of autosomal dominant genetic diseases, multisystem disorders excluding renal anomalies. There are clinical heterogeneity and ethnic diversity in BOS, which reported in more studies in European populations than in Asian populations, with a prevalence rate of approximately 1/40000. As the most common disease-causing gene, the mutation types of EYA1 range from missense to various frameshift, splicing and nonsense variants. Although splicing mutations are one of the important factors in the disease, existed research has paid less attention to the novel mutations causing aberrant RNA splicing and their pathogenic mechanisms. Reproductive interventions that actively block the transmission of the disease to future generations have also not been reported.

Methods: We had collected research samples from a three-generation Chinese family with BOS. Whole exome sequencing was applied for the screening of candidate causing gene. Minigene assay was performed to identify the aberrant splicing products, and molecular biology techniques were used to analyze the pathogenicity of potentially mistranslated proteins. pre-implantation genetic testing (PGT) has been employed to prevent hearing loss in this family based on SNP analysis.

Results: A novel mutation EYA1:c.1598-2AG>TA was identified by whole-exome sequencing and classified as harmful refer to ACMG's evidence. An aberrant RNA splicing was verified and suggested that might prematurely terminates the translation of EYA1 protein, through the minigene assay. The EYA1 truncated protein presented unstable and difficultly translocated to the nucleus, also impaired EYA1-SIX1 interactions in cytological experiments. PGT helped the proband give birth to a healthy boy.

Conclusion: A novel splicing variant of EYA1 gene was identified in this study, and the potential molecular pathogenic mechanism was elucidated by several functional experiments. On basis above findings, we successfully implemented the first instance of using PGT to ensure the birth of a healthy offspring free from this genetic disorder.