Analysis of audiological characteristics and genetic background in patients with nonsyndromic deafness and mitochondrial DNA 1555A>G mutation

Abstract

To analyze the audiological features and genetic background of patients carrying mitochondrial DNA(mtDNA) 1555A>G mutation and factors which may influence the extent of nonsyndromic hearing loss associated with the mutation. A literature search was carried out on databases including PubMed, CNKI, Wanfang, and VIP. Combined with author's data, the clinical features of the patients, in particular audiological characteristics, were summarized. A total of 857 effective cases were collected and analyzed. A significantly correlation was identified between history of aminoglycosides exposure and extent of hearing loss, in addition with a negative correlation between the age of onset and extent of hearing-impairment. Drug exposure was corelated with the age of onset but independent to the loss of high-frequency hearing loss. Heteroplasmies had a reverse correlation with the degree of hearing loss. Among the haplotypes of mitochondrial DNA, haplotype D was the most common one, while haplotype B had the highest penetrance. Nonsyndromic hearing loss associated with mitochondrial DNA 1555A>G mutation is influenced by factors such as aminoglycosides exposure, age, proportion of mutation, and haplotype of the mitochondrial DNA. Analysis of clinical cases is critical for identifying individuals carrying deafness susceptibility mutations and is the first step for early diagnosis.