PMC6787284_01
Muscle morphological studies. P1 left deltoid muscle biopsy at 34 years showed the presence of enlarged mitochondria with uneven distribution evident with Gomori trichrome staining (mGT) (A). Oxidative reactions (NADH) demonstrated the presence of an altered mitochondrial network giving rise to lobulation and type 1 predominance (B). P3 left deltoid biopsy at the age of 68 years old, revealed COX oxidative reaction (C) and the presence of mitochondrial aggregates evident with Gomori trichrome staining (mGT) (D).
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F2
P1 underwent left deltoid muscle biopsy at 34 years of age showing mitochondrial aggregates evidenced by Gomori trichrome staining (mGT) (Figure 2A) and NADH oxidative reaction (Figure 2B). Oxidative staining revealed the presence of type 1 fibers uniformity and rare areas of uneven oxidative reactions (Figure 2B). P3 underwent left deltoid biopsy at 68 years revealing loss of COX activity in some fibers (Figure 2C), a lobulated aspect of several muscle fibers and the presence of subsarcolemmal mitochondrial aggregates (Figure 2D).
Long range PCR. Long range PCR showing multiple deletions on muscle mtDNA in P3 compared to a patient showing a single mtDNA single deletion (C), a POLG mutated patient with a similar age showing multiple deletions (C2), and a normal control (NC).
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F3
In contrast we demonstrated the presence mtDNA multiple deletions on DNA extracted from skeletal muscle in P3 (Figure 3). The abnormalities observed in our patient were absent in muscle DNA from a 45 years healthy control suggesting that they are pathologic (Figure 3). As an age-matched muscle DNA was not available we used a DNA sample extracted from muscle of a 45 years subject as a normal control (Figure 3). Furthermore they were similar in intensity to those observed in the multiple deletions control (patient with POLG known mutations aged of P3) (Figure 3).