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Mitochondrial immunofluorescence assay as an adjunctive tool in the diagnosis of mitochondrial myopathy
Author(s) -
RiveraZengotita Marie,
Mehta Vidya,
Craigen Williams,
Scaglia Fernando,
Bhattacharjee Meenakshi,
Wong LeeJun,
Adesina Adekunle M.
Publication year - 2008
Publication title -
the faseb journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.709
H-Index - 277
eISSN - 1530-6860
pISSN - 0892-6638
DOI - 10.1096/fasebj.22.1_supplement.708.20
Subject(s) - mitochondrial myopathy , immunofluorescence , myopathy , mitochondrion , enzyme assay , pathology , biology , heteroplasmy , medicine , enzyme , microbiology and biotechnology , biochemistry , immunology , mitochondrial dna , antibody , gene
In the modified Walker criteria, the diagnosis of mitochondrial myopathy is supported by decrease in respiratory chain complex (RCC) enzyme activity below the 30 th percentile. Due to heteroplasmy, many symptomatic patients with clinical suspicion of mitochondrial disorders do not have biochemical assay levels meeting this criterion, thus requiring sensitive adjunctive assay methods for the detection of reduced RCC protein expression in these patients. We present the results of a mitochondrial immunofluorescence (MIF) assay using frozen muscle tissue for the detection of specific RCC enzyme defects. A total of 31 muscle biopsies from patients with suspected mitochondrial myopathy were analyzed for Complex I, II, III and IV specific proteins by MIF and for enzyme activity by standard biochemical methods. The frequency of abnormal expression of RCC proteins by MIF was Complex I ‐ 66.7%; Complex II ‐ 61.3%; and complex IV ‐ 35.5% compared with 12.9 %, 12.9% and 19.4%, respectively, using the recommended 30 th percentile cutoff for reduced enzyme activity. Widespread or regional reduced expression of RCC proteins was seen in many biopsies with biochemical enzyme activities ranging between the 30 th and 65 th percentiles (Complex I – 54.8%; Complex II – 48.4%; Complex III – 45.2%; Complex IV – 16.1%). We recommend the use of MIF assay as a supplement to current diagnostic methods for the detection of mitochondrial disorders.