PMC9194440_01
Histological and mtDNA studies in RNASEH1-mutated patients (P1 and P2). (A, B) Modified Gomori trichrome (MGT) showing the presence of ragged red fibers in patients' muscle sections. (C, D) SDH staining showed the presence of SDH-positive fibers. (E, F) COX histochemical reaction documenting the presence of COX-negative fibers. Magnification 40x. Scale bar 50 mum. (G) Long-range PCR analysis of mitochondrial DNA obtained from the probands' muscle biopsy (P1 and P2) and healthy controls (C). Asterisks indicate multiple bands corresponding to multiple mtDNA deletions. The black arrow indicates the expected size of the wild-type PCR amplicon (10.5 kB: FOR5635-RC16135). The sizes of the bands of the DNA molecular weight marker II (MW, Roche) are indicated. (H) Histogram showing levels of muscle 7S mtDNA in patients compared to healthy controls (n = 14). The ratio (RQ) indicates 7S mtDNA levels with respect to the total number of mitochondrial genomes amplified by quantitative PCR. Error bars indicate standard deviations. (I) Histogram showing muscle mtDNA content in the proband compared to healthy controls (n = 27). mtDNA quantification, normalized to nuclear DNA (nDNA) content, was performed by quantitative PCR. Error bars indicate standard deviations.
fgene-13-906667-g001.jpg
PMC9194440_02_fgene-13-906667-g001.jpg
F1
MRI showed cerebellar atrophy. Muscle biopsy revealed significant fiber size variation, necrosis and regenerating fibers, fiber type grouping at ATPase pH 4.3 (predominantly 2A and, to a lesser extent, 2C; rarely 2B), increased lipid storage, and mitochondrial dysfunction features including some RRFs and several COX-negative fibers (36.07%) (Figures 1B, D, F).
PMC9194440_02
Histological and mtDNA studies in RNASEH1-mutated patients (P1 and P2). (A, B) Modified Gomori trichrome (MGT) showing the presence of ragged red fibers in patients' muscle sections. (C, D) SDH staining showed the presence of SDH-positive fibers. (E, F) COX histochemical reaction documenting the presence of COX-negative fibers. Magnification 40x. Scale bar 50 mum. (G) Long-range PCR analysis of mitochondrial DNA obtained from the probands' muscle biopsy (P1 and P2) and healthy controls (C). Asterisks indicate multiple bands corresponding to multiple mtDNA deletions. The black arrow indicates the expected size of the wild-type PCR amplicon (10.5 kB: FOR5635-RC16135). The sizes of the bands of the DNA molecular weight marker II (MW, Roche) are indicated. (H) Histogram showing levels of muscle 7S mtDNA in patients compared to healthy controls (n = 14). The ratio (RQ) indicates 7S mtDNA levels with respect to the total number of mitochondrial genomes amplified by quantitative PCR. Error bars indicate standard deviations. (I) Histogram showing muscle mtDNA content in the proband compared to healthy controls (n = 27). mtDNA quantification, normalized to nuclear DNA (nDNA) content, was performed by quantitative PCR. Error bars indicate standard deviations.
fgene-13-906667-g001.jpg
PMC9194440_02_fgene-13-906667-g001.jpg
F1
MRI showed cerebellar atrophy. Muscle biopsy revealed significant fiber size variation, necrosis and regenerating fibers, fiber type grouping at ATPase pH 4.3 (predominantly 2A and, to a lesser extent, 2C; rarely 2B), increased lipid storage, and mitochondrial dysfunction features including some RRFs and several COX-negative fibers (36.07%) (Figures 1B, D, F).
Timeline of relevant clinical signs and symptoms and of diagnostic testing performed during disease progression of both patients.
fgene-13-906667-g002.jpg
PMC9194440_02_fgene-13-906667-g002.jpg
F2