Bilateral sensorineural hearing loss in members of a maternal lineage with a mitochondrial point mutation

Abstract

Pure-tone audiometry was carried out on members of a recently described maternal lineage with sensorineural deafness, harbouring a novel mitochondrial mutation in the gene for tRNA-ser(UCN). This revealed a characteristic pattern of symmetrical bilateral sensorineural hearing losses in each affected individual, predominantly affecting the high-frequencies, but with considerable variability between individuals. No clear correlation was observed between age and severity, but most subjects reported progressive worsening of their condition. Some members of the lineage were found to be heteroplasmic for the tRNA-ser(UCN) mutation. However, the severity of hearing loss was poorly correlated with the representation of the mutant mtDNA, indicating that other, as yet unidentified factors must be involved in the aetiology of this disorder.

Complete Inactivation of the TSC2 Gene Leads to Formation of Hamartomas

“…An additional mutation in a nuclear gene has been postulated as one possible cause for the latter, but efforts to identify such a modifier gene have not been successful (Guan et al 1996;Bykhovskaya et al 1998). Another mitochondrial mutation, A7445G, was initially identified, in a Scottish pedigree, as a cause of sensorineural hearing loss with incomplete penetrance (Reid et al 1994;Vernham et al 1994). In two subsequent pedigrees, from New Zealand and Japan, a relatively mild palmoplantar keratoderma (MIM 148350) was also noted in most affected individuals (Sevior et al 1998).…”

Whole mitochondrial genome screening in maternally inherited non-syndromic hearing impairment using a microarray resequencing mitochondrial DNA chip

“…4 (MITOMAP: A Human Mitochondrial Genome Database, http://www.mitomap.org). All of these mutations are localized in the ribosomal RNA 12S gene (MTRNR1 (MIM 561000)) or in the transfer RNAser(UCN) gene (MTTS1 (MIM 590080)), and have been reported in different countries and on different haplotype backgrounds.…”

As deficiências auditivas relacionadas às alterações do DNA mitocondrial.

“…O tratamento de uma doença mitocondrial ainda está em fase de pesquisa: alguns autores citam a terapia gênica ou a produção laboratorial de cofatores 11,26 como tratamentos para o futuro.…”