Refining the DFNB7-DFNB11 deafness locus using intragenic polymorphisms in a novel gene, TMEM2

Area of Science:

• Genetics
• Molecular Biology
• Auditory Science

Background:

• The DFNB7-DFNB11 locus associated with congenital hearing loss was previously mapped to chromosome 9q13-q21.
• Identifying the causative genes for hereditary deafness is crucial for genetic counseling and potential therapeutic strategies.

Purpose of the Study:

• To identify the gene responsible for hearing loss at the DFNB7-DFNB11 locus.
• To investigate the role of the novel gene TMEM2, located within the critical interval, in causing deafness.

Main Methods:

• Determined the cDNA sequence and genomic structure of the TMEM2 gene.
• Analyzed the expression of the mouse orthologue (Tmem2) in the cochlea.
• Screened the coding region of TMEM2 in families affected by DFNB7-DFNB11 deafness using direct sequencing.
• Utilized allele-specific amplification to differentiate pathogenic variants from common polymorphisms.
• Performed Northern blot analysis to compare Tmem2 expression in normal and deaf mice.

Main Results:

• The novel gene TMEM2, expressed in the cochlea, maps to the DFNB7-DFNB11 locus.
• No disease-causing mutations in TMEM2 were identified in affected individuals; all variants were common polymorphisms.
• Tmem2 expression levels and transcript size were similar in deaf and control mice.
• Intragenic TMEM2 polymorphisms established a new centromeric boundary for the DFNB7-DFNB11 interval.

Conclusions:

• TMEM2 is unlikely to be the causative gene for hearing loss at the DFNB7-DFNB11 locus.
• The identified TMEM2 polymorphisms provide a refined genetic map for the DFNB7-DFNB11 region.
• Further research is needed to identify the actual gene responsible for DFNB7-DFNB11 deafness.