Molecular Investigation of the A1555G Mitochondrial Mutation in Brazilian Patients

ABSTRACT

Among the alterations caused by the use of aminoglycosides, the A1555G mitochondrial mutation is one of the most important ones.

To investigate the prevalence of the A1555G mutation in patients with sensorineural hearing loss related with or without the use of aminoglycoside antibiotics.

Study of control-case in a sample of 27 patients with hearing loss, as the cases, and in 100 neonates, with normal hearing, as the control group. DNA was extracted from leukocyte blood samples and specific primers were used to amplify the Cytochrome b gene and the region that encloses the A1555G mutation of the mitochondrial DNA, using the polymerase chain reaction and the restriction fragment length polymorphism techniques.

The presence of mitochondrial DNA was confirmed in all of the 127 study samples, due to the amplification of the Cytochrome b gene region in all such samples. The A1555G has not been identified in any of the 27 patients with hearing loss, nor in the 100 neonates of the control group.

Results are in accordance with studies which state that the A1555G mutation is not prevalent in the Americas. There is some interest in determining the real prevalence of this mutation and in the investigation of other mutations which may cause hearing loss associated to the use of aminoglycosides, or not, in the Brazilian population.