Screening for deafness-associated mitochondrial 12S rRNA mutations by using a multiplex allele-specific PCR method

Area of Science:

• Genetics
• Otolaryngology
• Molecular Biology

Background:

• Mitochondrial 12S rRNA mutations A1555G and C1494T are primary causes of hearing loss.
• These mutations confer sensitivity to aminoglycoside antibiotics, necessitating screening before treatment.

Purpose of the Study:

• To evaluate a novel multiplex allele-specific PCR (MAS-PCR) for detecting A1555G and C1494T mutations in deaf patients.
• To investigate the genetic background and clinical phenotypes associated with these mitochondrial mutations.

Main Methods:

• A cohort of 500 deaf patients and 300 controls were screened using MAS-PCR.
• Positive cases were confirmed by Sanger sequencing.
• Mitochondrial genomes of matrilineal relatives were analyzed.

Main Results:

• MAS-PCR successfully identified two patients with A1555G and one with C1494T mutations, consistent with Sanger sequencing.
• Variable hearing loss phenotypes were observed.
• Associated mitochondrial mutations (tRNACys T5802C, tRNALys A8343G, tRNAThr G15930A) were identified, potentially impacting tRNA metabolism and causing mitochondrial dysfunction.
• Nuclear genes (GJB2, GJB3, GJB6, TRMU) showed no functional variants, suggesting limited nuclear gene involvement.

Conclusions:

• MAS-PCR is a rapid and convenient method for screening 12S rRNA mutations.
• Early detection of these mutations aids in preventing aminoglycoside-induced deafness.
• Both aminoglycosides and mitochondrial genetic background contribute to the clinical expression of deafness.