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Hearing Loss in Mitochondrial Disorders
Author(s) -
HSU CHANGHUNG,
KWON HAEYOUNG,
PERNG CHERNGLIH,
BAI RENKUI,
DAI PU,
WONG LEEJUN C.
Publication year - 2005
Publication title -
annals of the new york academy of sciences
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.712
H-Index - 248
eISSN - 1749-6632
pISSN - 0077-8923
DOI - 10.1196/annals.1338.004
Subject(s) - mitochondrial dna , hearing loss , mitochondrial disease , lactic acidosis , mitochondrion , point mutation , mitochondrial myopathy , etiology , pathology , respiratory chain , biology , mitochondrial respiratory chain , disease , genetics , medicine , mutation , gene , audiology
A bstract : Hearing loss is a common clinical feature in mitochondria‐syndrome disorders. The underlining molecular etiology of hearing loss has not been fully investigated. In this study, 83 patients with mitochondrial syndromic hearing loss were evaluated clinically and their blood and tissue samples were examined molecularly. Using modified Walker's criteria, 31, 31, 14, and 7 patients had been classified as having definite, probable, possible, and unlikely diagnosis of mitochondrial disease, respectively. Deleterious mtDNA point mutations and/or abnormal mtDNA content or multiple deletions were identified in 20 patients with definite diagnosis and 2 patients with probable diagnosis. In addition to known, undisputed pathogenic mutations, several novel mutations believed to be clinically significant were found. Furthermore, abnormal mtDNA content and mtDNA deletions were found in some of the cases. Evaluation of clinical and diagnostic features associated with hearing loss revealed that cardiomyopathy, lactic acidosis, deficient respiratory chain enzyme complex activities, histochemical and ultrastructural abnormalities in mitochondria, and abnormal brain imaging results occurred significantly more frequently in patients with mtDNA alterations than in those without. This study revealed that the majority of the mtDNA defects in patients with mitochondrial syndromic hearing loss affect the overall mitochondrial gene expression.