A new MYH2 variant in an Italian patient expanding the clinical spectrum of MYH2-related myopathy

Figures

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  Fig. 1. Muscle biopsy. H&E (A) and MTG (B) show fiber size variability, the presence of hyperchromic intracytoplasmic areas (asterisk at the inset), vacuoles with fuchsinophilic subsarcolemmal reinforcement. NADH (C) and COX (D) activities are centrally rarefied in some fibers. ATPase at pH 4.6 (E) shows the prevalence of type I fibers compared to normal fiber type distribution in control muscle (F). Immunofluorescent staining for slow-MHC confirms the prevalence of type I fibers (G) compared to control (H). Membrane fibers were counterstained with caveolin-3 and nuclei with DAPI. Scale bar 50 μm

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  Fig. 2. Genetic and protein findings. A Electropherogram showing the homozygous nucleotide change c.3901G > T in our patient and segregation analysis in his unaffected parents. B Analysis of the relative level of expression of different isoforms of MyHC mRNA in patient’s and control’s muscles (mean of two independent PCR analysis). C Immunofluorescent staining for MyHC-IIa in patient and control; laminin-α2 for membrane staining and DAPI for nuclei counterstaining. Scale bar 50 μm. D Western blot analysis of MyHC-IIa levels in patient’s and control’s muscles

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  Fig. 3. Immunofluorescence of protein aggregates. p62 positivity in some fibers (A). B: Control muscle staining for p62. αB-crystallin-positive protein aggregates of variable size in some fibers (C). D: Control muscle staining for αB-crystallin. TDP-43 evidence of cytoplasmic aggregates delimited by caveolin-3-positive membrane (E). F: Control muscle staining for TDP-43. Membrane alterations and scattered cytoplasmic aggregates detected with caveolin-3 membrane staining (G, H). Scale bar 50 μm. Immunofluorescence of sarcomeric proteins. Immunofluorescence staining for α-actinin (I), nebulin (K) and titin (M, O) in patient and control (J, L, N, P) muscle. Caveolin-3 (red) and DAPI (blue) counterstained membranes and nuclei. Scale bar 50 μm

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  Fig. 4. Ultrastructural findings. A Alterations in the sarcomeric structure observed at ultrastructural examination: Z-band streaming (A), accumulation of electron-dense granulofilamentous aggregates (B), presence of filamentous bodies (C). Areas of filament disarray and Z line fragmentation with initial nemaline body formation (D). Scale bar: 715 nm (B-C)- 1135 nm (A-D)

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  Fig. 5. Schematic representation of MYH2 gene structure, protein domains and distributions of reported pathogenic MYH2 variants with recessive (AR, above the scheme of the gene) or dominant (AD, under the scheme of the gene) inheritance