Mitochondrial DNA mutations and non-syndromic sensorineural hearing loss

Objective: To analyze the incidence of three types of mitochondrial DNA mutations in the non-syndromic sensorineural hearing loss (NSSNHL) patients and control subjects in order to investigate the possible role of mitochondrial DNA mutations in NSSNHL.

Methods: Sixty-one sporadic NSSNHL patients (from 3 to 84 years old) and 19 control subjects matched for age were selected. DNA was extracted from isolated blood leukocytes. Interrupt polymerase chain reaction (PCR) and primer-shift PCR were used to detect the mtDNA4977 deletion; mtDNA1555A-->G and mtDNA3243A-->G point mutation were detected by PCR and restriction fragment length polymorphism (RFLP) analysis. PCR products were sequenced by automated laser fluorescent DNA sequencer.

Results: The detection rate of mtDNA4977 deletion in deafness groups and control groups are 68.85%(42/61) vs. 5.26%(1/19). Among all the samples, neither any mtDNA1555A-->G mutation nor mtDNA3243A-->G point mutation was detected.

Conclusions: MtDNA4977 deletion had a high detection rate in patients with NSSNHL. MtDNA1555A-->G mutation and mtDNA3243A-->G point mutation may not be common mutations in patients with NSSNHL.