Identification and Functional Characterization of a Novel POU3F4 Frameshift Mutation in a Chinese Family

Area of Science:

• Genetics
• Molecular Biology
• Otolaryngology

Background:

• Hereditary sensorineural hearing loss (SNHL) is a major health concern.
• DFNX2, an X-linked non-syndromic SNHL, is linked to the POU3F4 gene.
• Understanding POU3F4 mutations is crucial for DFNX2 pathogenesis.

Purpose of the Study:

• Identify a novel POU3F4 mutation in a Chinese family with X-linked deafness.
• Investigate the functional consequences of the identified mutation.
• Elucidate the molecular mechanisms underlying DFNX2.

Main Methods:

• Targeted next-generation sequencing and Sanger sequencing for variant identification and co-segregation analysis.
• Functional assays: subcellular localization, dual-luciferase reporter assay, Western blotting.
• Homology modeling for structural analysis of the mutation's impact.

Main Results:

• A novel frameshift mutation (c.670_673dupGGTA, p.(Asn225Argfs*2)) in POU3F4 was identified and co-segregated with deafness.
• The mutant POU3F4 protein showed cytoplasmic mislocalization and significantly reduced transcriptional activity.
• Structural modeling indicated loss of DNA-binding subdomains (POUS and POUH).

Conclusions:

• The study expands the known POU3F4 mutation spectrum for DFNX2.
• The identified mutation disrupts POU3F4 function through mislocalization and impaired DNA binding.
• These findings reinforce established mechanisms of DFNX2 pathogenesis.