Postlingual hearing loss as a mitochondrial 3243A>G mutation phenotype

• Published in: PloS one 2012-10, Vol.7 (10), p.e44054-e44054
• Main Authors: Iwanicka-Pronicka, Katarzyna, Pollak, Agnieszka, Skórka, Agata, Lechowicz, Urszula, Pajdowska, Magdalena, Furmanek, Mariusz, Rzeski, Maciej, Korniszewski, Lech, Skarżyński, Henryk, Płoski, Rafał
• Format: Article
• Language: English
• Subjects: Adenine - chemistry; Adolescent; Adult; Age; Age of Onset; Auditory defects; Biology; Blood; Brain - pathology; Carriers; Deoxyribonucleic acid; Diabetes; Disease; DNA; DNA - analysis; DNA Mutational Analysis; DNA, Mitochondrial - genetics; Enzymes; Female; Genetic testing; Genotype & phenotype; Guanine - chemistry; Hearing impairment; Hearing loss; Hearing Loss, Sensorineural - epidemiology; Hearing Loss, Sensorineural - genetics; Heteroplasmy; Heterozygote; Humans; Magnetic Resonance Imaging - methods; Male; Medicine; Middle Aged; Mitochondria; Mitochondrial DNA; Mutation; Pathology; Patients; Physiology; Poland; Sex Factors; Spectrum analysis; Urine
• ISSN: 1932-6203; 1932-6203
• DOI: 10.1371/journal.pone.0044054

The prevalence of isolated hearing loss (HL) associated with the m.3243A>G mutation is unknown. The aim of this study was to assess the frequency and heteroplasmy level of the m.3243A>G mutation in a large group of Polish patients with postlingual bilateral sensorineural HL of unidentified cause. A molecular search was undertaken in the archival blood DNA of 1482 unrelated patients with isolated HL that had begun at ages between 5 and 40 years. Maternal relatives of the probands were subsequently investigated and all carriers underwent audiological tests. The m.3243A>G mutation was found in 16 of 1482 probands (an incidence of 1.08%) and 18 family members. Of these 34 individuals, hearing impairment was detected in 29 patients and the mean onset of HL was at 26 years. Some 42% of the identified m.3243A>G carriers did not develop multisystem symptomatology over the following 10 years. Mean heteroplasmy level of m.3243A>G was lowest in blood at a level of 14% and highest in urine at 58%. These values were independent of the manifested clinical severity of the disease. A single m.3243A>G carrier can usually be found among each 100 individuals who have postlingual hearing loss of unknown cause. Urine samples are best for detecting the m.3243A>G mutation and diagnosing mitochondrially inherited hearing loss.