Study of a Brazilian family presenting non-syndromic hearing loss with mitochondrial inheritance.
We hereby report on the audiological and genetic findings in individuals from a Brazilian family, with the following mitochondrial mutation A1555G in the 12SrRNA gene (MT-RNR-1). Nine individuals underwent speech, audiologic (tonal audiometry and logoaudiometry) and genetic evaluations. Eight individuals among the A1555G carriers were affected by hearing impairment and one person had normal hearing thresholds till the end of the present study. The audiologic evaluation results indicated normal hearing thresholds all the way to bilateral profound hearing loss with post-lingual onset and variable configuration. Two affected siblings presented progressive hearing loss. It was impossible to precise the time of hearing loss onset; however, the impairment was present in both children and adults. The genetic study revealed the A1555G mitochondrial mutation in the 12SrRNA gene. Given the prevalence of mitochondrial mutations as a cause of hearing loss, it is fundamental to perform the etiopathologic diagnosis in order to postpone the onset or avoid hearing impairment progression. This kind of hearing impairment represents a challenge to the professionals since there are no physical traits that indicate genetic transmission.
Pupo
Altair Cadrobbi
AC
PhD in Communication Disorders at UNIFESP, Head of Department at speech and hearing therapy clinic - PUC/SP.
Pirana
Sulene
S
PhD in Medicine at Universidade de São Paulo, Associate Professor at the Speech and Hearing Therapy School at PUC-SP.
Spinelli
Mauro
M
PhD in Sciences - Communication Disorders at PUC-SP, Full Professor of Speech Therapy at PUC-SP.
Lezirovitz
Karina
K
MSc in Sciences at Universidade de São Paulo. PhD student at the Institute of Biosciences at USP, Biologist.
Netto
Regina C Mingroni
RCM
PhD in Sciences at Universidade de São Paulo, Professor at the Institute of Biosciences at USP.
Macedo
Lisandra S
LS
Specialist Speech and Hearing Therapist at PUC-SP, Speech and Hearing Therapist at Hospital e Maternidade Alvorada. Pontifícia Universidade Católica de São Paulo and Universidade de São Paulo. Electronic address: lisandra_macedo@yahoo.com.br.
D000328:Adult; D001299:Audiometry; D001938:Brazil; D002648:Child; D002675:Child, Preschool; D004272:DNA, Mitochondrial / Q000235:genetics*; D050259:Genes, Mitochondrial / Q000235:genetics*; D020022:Genetic Predisposition to Disease; D034381:Hearing Loss / Q000235:genetics*; D006319:Hearing Loss, Sensorineural / Q000235:genetics; D006801:Humans; D008875:Middle Aged; D009154:Mutation; D010375:Pedigree
D004272:DNA, Mitochondrial