Table 1.
Comparison of muscle histopathological findings in different genetic motor neuron disorders.
All P values in the right-most column apply to comparisons of both C9ALS versus SBMA and C9ALS versus SMAJ. None of the differences between SMAJ and SBMA groups were statistically significant. SMAJ = spinal muscular atrophy, Jokela type, SBMA = spinal and bulbar muscular atrophy, C9ALS = amyotrophic lateral sclerosis caused by pathological hexanucleotide expansion in the gene C9orf72. NA = not available.
Table 2.
Antibodies used for immunohistochemistry, dilutions and suppliers.
Fig 1.
Neurogenic muscle biopsy findings in SMAJ, SBMA and c9ALS.
Small groups of rounded type IIA fibers (arrows) in a vastus lateralis muscle biopsy of a 48-year-old male with SMAJ (A). Extensive fiber type grouping involving non-atrophic type IIA fibers (arrows) shown in a tibialis anterior biopsy of a 55-year-old SMAJ female patient (B). Groups of angulated atrophic fibers with mixed fiber types (arrows) in a vastus lateralis muscle of a 52-year-old female patient with c9ALS (C). Small groups of extremely atrophic type IIA fibers (inset) in a tibialis anterior biopsy of a 60-year-old male patient with SBMA (D). Figs A-D: myosin heavy chain double stain immunohistochemistry showing type IIA fibers in red, IIX fibers in blue and type I fibers in brown color. Scale bar = 100 micrometers
Table 3.
Additional immunohistochemical studies in SMAJ and SBMA patients with rimmed vacuoles and/or myofibrillar pathology.
ND = not defined, alphaBC = alphaB-crystallin, Dys-2 = dystrophin c-terminus, SMAJ = SMA Jokela type, SBMA = spinal and bulbar muscular atrophy, RV = rimmed vacuoles, CA = “cytoplasmic body” aggregates, VL = vastus lateralis, Gcmed = gastrocnemius medialis. -, normal or no immunoreactivity; +, immunoreactivity present/mild abnormality; ++ moderate immunoreactivity/abnormality; +++, high immunoreactivity/abnormality.
Fig 2.
Secondary “myopathic” changes in SMAJ.
2: Unusually pronounced myofibrillar and autophagic pathology in a gastrocnemius medialis biopsy of a 67-year-old female with SMAJ. H&E and herovici stainings (A and E) showing endomysial fibrosis, fiber size variation, internal nuclei, as well as large myofibrillar aggregates (asterisk, A-B, E-G), several rimmed vacuolated fibers (vertical arrows) and one”cytoplasmic body” aggregate (black horizontal arrow). The myofibrillar aggregates are strongly myotilin immunoreactive (B) and show also some reactivity for p62 and SMI-31 (F and G). The rimmed vacuolar areas contain LC3 (C) and ubiquitin (D) positive material (with our antibody and protocol nuclei are also stained besides ubiquitinated cytoplasmic material). The rimmed vacuolated fibers are also strongly reactive for p62, SMI-31 and TDP-43 (F-H).
Fig 3.
Secondary “myopathic” changes in SBMA.
Muscle biopsy from a vastus lateralis biopsy of a 46-year-old male patient with SBMA showing internal nuclei, rimmed vacuoles (RV, yellow arrows, A-B), one RV and”cytoplasmic body” aggregate (green arrow), core-lobulated fibers with myofibrillar aggregates (black arrows in A-B, yellow arrows in C) that are strongly myotilin immunoreactive (yellow arrows, D).
Fig 4.
Lack of mitochondrial abnormalities in SMAJ.
Immunohistochemical CHCHD10 staining in normal muscle sample (A) and muscle sample from SMAJ patient (C) showing no difference in expression and location of CHCHD10. The CHCHD10 staining is more prominent in type 1 fibers. The corresponding myosin double stainings are shown of the same muscles (B, D). Electron micrographs from deltoideus muscle of a 42-year-old SMAJ patient show morphologically normal mitochondria beneath the sarcolemma (E) and a subsarcolemmal tubular aggregate (F).