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Hearing Impairment Is Common in Various Phenotypes of the Mitochondrial DNA A3243G Mutation
Marcus Deschauer, MD;
Tobias Müller, MD;
Thomas Wieser, MD;
Wilhelm Schulte-Mattler, MD;
Malte Kornhuber, MD;
Stephan Zierz, MD
Arch Neurol. 2001;58:1885-1888.
Objective To determine whether there are common symptoms
within different phenotypes of the mitochondrial DNA A3243G mutation.
Design A series of 52 adults with mitochondrial
encephalomyopathies and their symptomatic relatives were screened for
the A3243G mutation using restriction enzyme analysis. In addition to
clinical examination, patients with the mutation underwent audiometry.
Results The A3243G mutation was identified in 16 patients (10
index patients and 6 symptomatic relatives). Six of these
patients presented with strokelike episodes and met the classical
criteria of MELAS syndrome (mitochondrial myopathy, encephalopathy,
lactic acidosis, and strokelike episodes), and one had MELAS/MERRF
(myoclonic epilepsy with ragged-red fibers) overlap syndrome. Two
patients presented with strokelike episodes but did not meet the
classical criteria of MELAS. Predominant features of the 8 other
patients were myopathy with hearing loss and diabetes mellitus
(n = 1), chronic progressive external ophthalmoplegia
(n = 1), diabetes mellitus with hearing loss
(n = 1), painful muscle stiffness with hearing loss
(n = 1), cardiomyopathy (n = 1), diabetes
mellitus (n = 1), and hearing loss
(n = 2). In 11 of 16 patients, hearing
impairment was obvious on clinical examination. Furthermore, all 5
patients with normal hearing on clinical examination showed subclinical
hearing loss; in 4, hearing loss was more pronounced than age-related
hearing impairment and in 1, hearing loss can be age related as well.
Conclusions A variety of phenotypes represent the
variable multisystemic involvement of the A3243G mutation. Less than
half of the patients presented with MELAS. Hearing impairment, the
most common symptom, was clinically or subclinically relevant in 15
(94%) of 16 patients.
From the Department of Neurology, Martin-Luther-Universität Halle-Wittenberg, Halle/Saale, Germany.
Corresponding author and reprints: Marcus Deschauer, MD, Department of
Neurology, Martin-Luther-Universität Halle-Wittenberg,
Ernst-Grube-Str. 40, D-06097 Halle, Germany (e-mail: marcus.deschauer{at}medizin.uni-halle.de).
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