[Mitochondrial DNA mutations and non-syndromic sensorineural hearing loss]

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.

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.

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.

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.