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We report on an adult Turkish patient with mild myopathy with a fiber-type disproportion and mitochondrial disorganization caused by genetic variants in the plectin gene (PLEC). Molecular genetic panel testing revealed two homozygous variants in PLEC (NM_000445.4): c.8306C>G (p.Pro2769Arg) and c.7506 + 5C>G (p. ?) that were classified as variants of unknown significance (class 3) following ACMG guidelines for variant classification in genetic diagnostics. A thorough reassessment of the patient revealed mild skin blistering (epidermolysis bullosa simplex, EBS). This illustrates the importance of deep phenotyping of neuromuscular patients.

Nemaline myopathies are a clinically and genetically heterogeneous group of congenital myopathies, mainly characterized by muscle weakness, hypotonia and respiratory insufficiency. Here, we report a male foetus of consanguineous parents with a severe congenital syndrome characterized by arthrogryposis detected at 13 weeks of gestation. We describe severe complex dysmorphic facial and musculoskeletal features by post mortem fetal examination confirming the prenatal diagnosis. Histomorphological and ultrastructural studies of skeletal muscle reveal mini-rods in myotubes caused by a novel homozygous splice-site mutation in NEB (NM_001164508, chr2:g.152,417,623C>A GRCh37.p11 | c.19,102-1G>T ENST00000397345.3). No rods were seen in the myocardium. We discuss the relevance of this mutation in the context of nemaline myopathies associated with early developmental musculoskeletal disorders.

Objective The neuronal ceroid lipofuscinoses (NCL) are genetic degenerative disorders of brain and retina. NCL with juvenile onset (JNCL) is genetically heterogeneous but most frequently caused by mutations of CLN3. Classical juvenile CLN3 includes a rare protracted form, which has previously been linked to autophagic vacuolar myopathy (AVM). Our study investigates the association of AVM with classic, non‐protracted CLN3. Methods Evaluation of skeletal muscle biopsies from three, non‐related patients with classic, non‐protracted and one patient with protracted CLN3 disease by histology, immunohistochemistry, electron microscopy, and Sanger sequencing of the coding region of the CLN3 gene. Results We identified a novel heterozygous CLN3 mutation (c.1056+34C>A) in one of our patients with classic, non‐protracted CLN3 disease. The skeletal muscle of all CLN3 patients was homogeneously affected by an AVM characterized by autophagic vacuoles with sarcolemmal features and characteristic lysosomal pathology. Interpretation Our observations show that AVM is not an exceptional phenomenon restricted to protracted CLN3 but rather a common feature in CLN3 myopathology. Therefore, CLN3 myopathology should be included in the diagnostic spectrum of autophagic vacuolar myopathies.

A 6-year-old girl had reduced fetal movements, numerous apneic spells, muscle hypotonia, and developmental motor delay. Her muscle biopsy tissue showed variation in myofiber diameters, small minicores by electron microscopy, and near-uniformity of type I fibers. Although no mutations were detected in RYR1, SEPN1, and DMPK genes, the RAPSN gene revealed one known mutation, p.Asn88Lys, from the mother, and one novel mutation, p.Cys366Gly, from the father. Life-saving pyridostigmine treatment suppressed her apneic spells and improved her motor development.

ObjectiveTo determine interrater variability in diagnosing individual muscle biopsy abnormalities and diagnosis.MethodsWe developed a scoring tool to analyze consensus in muscle biopsy reading of an ad hoc workgroup of international experts. Twenty-four samples from patients with suspected idiopathic inflammatory myopathy (IIM) were randomly selected, providing sections that were stained with standard histologic and immunohistochemical methods. Sections were made available on an online platform, and experts were queried about myopathologic features within 4 pathologic domains: muscle fibers, inflammation, connective tissue, and vasculature. A short clinical presentation of cases was included, and experts were asked to give a tentative diagnosis of polymyositis, dermatomyositis, inclusion-body myositis, antisynthetase syndrome–related myositis, immune-mediated necrotizing myopathy, nonspecific myositis, or other disease. Fleiss κ values, scoring interrater variability, showed the highest agreement within the muscle fiber and connective tissue domains.ResultsDespite overall low κ values, moderate agreement was achieved for tentative diagnosis, supporting the idea of using holistic muscle biopsy interpretation rather than adding up individual features.ConclusionThe assessment of individual pathologic features needs to be standardized and harmonized and should be measured for sensitivity and specificity for subgroup classification. Standardizing the process of diagnostic muscle biopsy reading would allow identification of more homogeneous patient cohorts for upcoming treatment trials.

Congenital myopathies (CM) are a large and heterogeneous group of disorders. Many new myopathies with congenital onset have recently been described phenotypically, and their molecular elucidation has rapidly ensued consecutively. CM reported between 2013 and 2017 and their corresponding gene defects have mostly been identified with modern molecular genetic techniques. Here, we report recently identified CM that have not been included in the 2017 gene table so far, of which some have been recognized with mutations in new genes and others have been recognized as variants of previously identified genes, associated with specific CM phenotypes.

Myalgia, increased levels of creatine kinase, and persistent muscle weakness have been reported in patients with COVID-19.To study skeletal muscle and myocardial inflammation in patients with COVID-19 who had died.This case-control autopsy series was conducted in a university hospital as a multidisciplinary postmortem investigation. Patients with COVID-19 or other critical illnesses who had died between March 2020 and February 2021 and on whom an autopsy was performed were included. Individuals for whom informed consent to autopsy was available and the postmortem interval was less than 6 days were randomly selected. Individuals who were infected with SARS-CoV-2 per polymerase chain reaction test results and had clinical features suggestive of COVID-19 were compared with individuals with negative SARS-CoV-2 polymerase chain reaction test results and an absence of clinical features suggestive of COVID-19.Inflammation of skeletal muscle tissue was assessed by quantification of immune cell infiltrates, expression of major histocompatibility complex (MHC) class I and class II antigens on the sarcolemma, and a blinded evaluation on a visual analog scale ranging from absence of pathology to the most pronounced pathology. Inflammation of cardiac muscles was assessed by quantification of immune cell infiltrates.Forty-three patients with COVID-19 (median [interquartile range] age, 72 [16] years; 31 men [72%]) and 11 patients with diseases other than COVID-19 (median [interquartile range] age, 71 [5] years; 7 men [64%]) were included. Skeletal muscle samples from the patients who died with COVID-19 showed a higher overall pathology score (mean [SD], 3.4 [1.8] vs 1.5 [1.0]; 95% CI, 0-3; P < .001) and a higher inflammation score (mean [SD], 3.5 [2.1] vs 1.0 [0.6]; 95% CI, 0-4; P < .001). Relevant expression of MHC class I antigens on the sarcolemma was present in 23 of 42 specimens from patients with COVID-19 (55%) and upregulation of MHC class II antigens in 7 of 42 specimens from patients with COVID-19 (17%), but neither were found in any of the controls. Increased numbers of natural killer cells (median [interquartile range], 8 [8] vs 3 [4] cells per 10 high-power fields; 95% CI, 1-10 cells per 10 high-power fields; P < .001) were found. Skeletal muscles showed more inflammatory features than cardiac muscles, and inflammation was most pronounced in patients with COVID-19 with chronic courses. In some muscle specimens, SARS-CoV-2 RNA was detected by reverse transcription-polymerase chain reaction, but no evidence for a direct viral infection of myofibers was found by immunohistochemistry and electron microscopy.In this case-control study of patients who had died with and without COVID-19, most individuals with severe COVID-19 showed signs of myositis ranging from mild to severe. Inflammation of skeletal muscles was associated with the duration of illness and was more pronounced than cardiac inflammation. Detection of viral load was low or negative in most skeletal and cardiac muscles and probably attributable to circulating viral RNA rather than genuine infection of myocytes. This suggests that SARS-CoV-2 may be associated with a postinfectious, immune-mediated myopathy.

Background Marinesco-Sjogren Syndrome (MSS) is a rare neuromuscular condition caused by recessive mutations in the SIL1 gene resulting in the absence of functional SIL1 protein, a co-chaperone for the major ER chaperone, BiP. As BiP is decisive for proper protein processing, loss of SIL1 results in the accumulation of misshaped proteins. This accumulation likely damages and destroys cells in vulnerable tissues, leading to congenital cataracts, cerebellar ataxia, vacuolar myopathy and other MSS phenotypes. Whether the peripheral nervous system (PNS) is affected in MSS has not been conclusively shown. Methods To study PNS vulnerability in MSS, intramuscular nerves fibres from MSS patients and from SIL1-deficient mice (woozy) as well as sciatic nerves and neuromuscular junctions (NMJ) from these mice have been investigated via transmission electron microscopic and immunofluorescence studies accompanied by transcript studies and unbiased proteomic profiling. In addition, PNS and NMJ integrity were analyzed via immunofluorescence studies in an MSS-zebrafish model which has been generated for that purpose. Results Electron microscopy revealed morphological changes indicative of impaired autophagy and mitochondrial maintenance in distal axons and in Schwann cells. Moreover, changes of the morphology of NMJs as well as of transcripts encoding proteins important for NMJ function were detected in woozy mice. These findings were in line with a grossly abnormal structure of NMJs in SIL1-deficient zebrafish embryos. Proteome profiling of sciatic nerve specimens from woozy mice revealed altered levels of proteins implicated in neuronal maintenance suggesting the activation of compensatory mechanisms. Conclusion Taken together, our combined data expand the spectrum of tissues affected by SIL1-loss and suggest that impaired neuromuscular transmission might be part of MSS pathophysiology.

The neuronal ceroid lipofuscinoses (NCL) currently encompass fourteen genetically different forms, CLN1 to CLN14, but are all morphologically marked by loss of nerve cells, particularly in the cerebral and cerebellar cortices, and the cerebral and extracerebral formation of lipopigments. These lipopigments show distinct ultrastructural patterns, i.e., granular, curvilinear/rectilinear and fingerprint profiles. They contain−although to a different degree among the different CLN forms−subunit C of ATP synthase, saposins A and D, and beta-amyloid proteins. Extracerebral pathology, apart from lipopigment formation, which provides diagnostic information, is scant or non-existent. The retina undergoes atrophy in all childhood forms. While many new data and findings have been obtained by immunohistochemistry in mouse and other animal models, similar findings in human NCL are largely missing, thus recommending respective studies of archived brain tissues. The newly described NCL forms, i.e., CLN 10 to CLN 14, also require further studies to provide complete neuropathology. This article is part of a Special Issue entitled: “Current Research on the Neuronal Ceroid Lipofuscinoses (Batten Disease)”.

Macrophagic myofasciitis (MMF) is a rare inflammatory myopathy which occurs after injection of aluminium-containing vaccines against hepatitis B virus (HBV), hepatitis A virus, and tetanus toxoid. Most of the cases reported are from France and are adult patients. We report a rare case of MMF in a 3-month-old male child of Indian origin. He was immunized for HBV at birth after which he developed generalized hypotonia, and central nervous system and peripheral nervous system manifestations at 1 month of age. Muscle biopsy showed typical features of MMF and aluminium could be detected in the muscle biopsy macrophages by ultrastructural examination and LAMMA technique. Our case is the youngest case of MMF and one of few from Asia. (J Pediatr Neurol 2004; 2(4): 225–229).

Objective To analyse the paradox of a lack of giant cell formation and fibrosis in chronic lesions of macrophagic myofasciitis (MMF) in comparison with muscular sarcoidosis (MuS). Methods Inflammatory lesions and contiguous muscle regions from biopsy samples of 10 patients with MuS and 10 patients with MMF were cut out by laser microdissection. Mediators of the T helper cell (Th)1 inducing classical macrophage activation (e.g. STAT1, IFNγ and CXCR3), and Th2 inducing alternative activation of macrophages (e.g. CD206/MRC1, STAT6, SOCS1), molecules involved in development of fibrosis (e.g. TGFβ) and giant cells (e.g. TYROBP), were assessed by immunohistochemistry and real-time polymerase chain reaction (PCR). Results STAT6-induced Th2 immunity was associated with up-regulated gene expression of MRC1, SOCS1 and TGFB in inflammatory foci, in comparison with adjacent tissue. TYROBP and TREM2, genes regulating giant cell formation, were more strongly expressed in lesions of MuS patients than in those of MMF. TGFβ co-localized with CD206+ macrophages in MuS but not in MMF. Conversely, Th1 immunity was illustrated by STAT1 staining both in macrophages and myofibres in MuS, but not in MMF. Also, STAT1-induced IFNG and CXCR3 expression in lesions and the surrounding tissue was elevated compared with normal controls, but without statistically significant differences. Conclusion Giant cell and typical granuloma formations, including fibrogenesis, is dependent on two main mechanisms, both involving specific macrophage activation: a strong Th2-M2 polarization and a significant expression of TYROBP and TGFβ in macrophages. The low-grade alternative activation of macrophages in MMF lesions and poor TYROBP and TGFβco-expression are obviously insufficient to produce giant cells.

Neurometabolic and neurodegenerative diseases in children (NDDC) differ from those in adults in that most of the former are autosomal-recessively inherited – few have X-linked inheritance – while the latter are often sporadic or autosomal-dominantly inherited. NDDC may be catabolic and/or anabolic conditions, some of which combine maldevelopmental and degenerative features, for instance, peroxisomal biogenesis disorders or congenital disorders of glycosylation. NDDC are often multiorgan disorders, such as lysosomal, peroxisomal, and polyglucosan disorders. This multiorgan involvement may be marked by extracerebral formation of disease-specific neuropathologic findings, especially in lysosomal diseases allowing diagnostic biopsies in easily accessible tissues, e.g., blood lymphocytes, skin, skeletal muscle, and rectum to be investigated by electron microscopy. NDDC comprise nonvacuolar and vacuolar lysosomal, peroxisomal, polyglucosan, amino and organic acid, white-matter disorders, and congenital disorders of glycosylation.

Multisystem proteinopathy (MSP) involves disturbances of stress granule (SG) dynamics and autophagic protein degradation that underlie the pathogenesis of a spectrum of degenerative diseases that affect muscle, brain, and bone. Specifically, identical mutations in the autophagic adaptor SQSTM1 can cause varied penetrance of 4 distinct phenotypes: amyotrophic lateral sclerosis (ALS), frontotemporal dementia, Paget's disease of the bone, and distal myopathy. It has been hypothesized that clinical pleiotropy relates to additional genetic determinants, but thus far, evidence has been lacking. Here, we provide evidence that a TIA1 (p.N357S) variant dictates a myodegenerative phenotype when inherited, along with a pathogenic SQSTM1 mutation. Experimentally, the TIA1-N357S variant significantly enhances liquid-liquid-phase separation in vitro and impairs SG dynamics in living cells. Depletion of SQSTM1 or the introduction of a mutant version of SQSTM1 similarly impairs SG dynamics. TIA1-N357S-persistent SGs have increased association with SQSTM1, accumulation of ubiquitin conjugates, and additional aggregated proteins. Synergistic expression of the TIA1-N357S variant and a SQSTM1-A390X mutation in myoblasts leads to impaired SG clearance and myotoxicity relative to control myoblasts. These findings demonstrate a pathogenic connection between SG homeostasis and ubiquitin-mediated autophagic degradation that drives the penetrance of an MSP phenotype.

Idiopathic inflammatory myopathies (IIM) represent a heterogeneous group of rare muscular diseases, with no clearly known causes. IIM frequently have an incomplete response to treatment due to the difficulty in distinguishing between IIM forms, and due to neglect their non-inflammatory causes. Important data concerning non-immune mechanisms in IIM pathology have been recently accumulated. There is a correlation between inflammatory and non-inflammatory mechanisms, but their involvement in IIM pathogenesis is still unknown. Here we review some of the most important data regarding the non-immune IIM pathology, highlighting possible future therapeutic targets: endoplasmic reticulum stress, ATP metabolism, ROS generation, autophagy, and microRNAs disturbances.

Hereditary diffuse leukoencephalopathy with axonal spheroids (HDLS) is an autosomal dominant disease clinically characterized by cognitive decline, personality changes, motor impairment, parkinsonism and seizures. Recently, mutations in the colony-stimulating factor-1 receptor (CSF1R) gene have been shown to be associated with HDLS. We report clinical, neuropathological and molecular genetic findings of patients from a new family with a mutation in the CSF1R gene. Disease onset was earlier and disease progression was more rapid compared with previously reported patients. Psychiatric symptoms including personality changes, alcohol abuse and severe depression were the first symptoms in male patients. In the index, female patient, the initial symptom was cognitive decline. Magnetic resonance imaging (MRI) showed bilateral, confluent white matter lesions in the cerebrum. Stereotactic biopsy revealed loss of myelin and microglial activation as well as macrophage infiltration of the parenchyma. Numerous axonal swellings and spheroids were present. Ultrastructural analysis revealed pigment-containing macrophages. Axonal swellings were detected by electron microscopy not only in the central nervous system (CNS) but also in skin nerves. We identified a heterozygous mutation (c.2330G>A, p.R777Q) in the CSF1R gene. Through this report, we aim to enlarge the nosological spectrum of HDLS, providing new clinical descriptions as well as novel neuropathological findings from the peripheral nervous system.

Marinesco-Sjögren syndrome (MSS) features cerebellar ataxia, mental retardation, cataracts, and progressive vacuolar myopathy with peculiar myonuclear alterations. Most MSS patients carry homozygous or compound heterozygous SIL1 mutations. SIL1 is a nucleotide exchange factor for the endoplasmic reticulum resident chaperone BiP which controls a plethora of essential processes in the endoplasmic reticulum. In this study we made use of the spontaneous Sil1 mouse mutant woozy to explore pathomechanisms leading to Sil1 deficiency-related skeletal muscle pathology. We found severe, progressive myopathy characterized by alterations of the sarcoplasmic reticulum, accumulation of autophagic vacuoles, mitochondrial changes, and prominent myonuclear pathology including nuclear envelope and nuclear lamina alterations. These abnormalities were remarkably similar to the myopathy in human patients with MSS. In particular, the presence of perinuclear membranous structures which have been reported as an ultrastructural hallmark of MSS-related myopathy could be confirmed in woozy muscles. We found that these structures are derived from the nuclear envelope and nuclear lamina and associate with proliferations of the sarcoplasmic reticulum. In line with impaired function of BiP secondary to loss of its nucleotide exchange factor Sil1, we observed activation of the unfolded protein response and the endoplasmic-reticulum-associated protein degradation-pathway. Despite initiation of the autophagy-lysosomal system, autophagic clearance was found ineffective which is in agreement with the formation of autophagic vacuoles. This report identifies woozy muscle as a faithful phenocopy of the MSS myopathy. Moreover, we provide a link between two well-established disease mechanisms in skeletal muscle, dysfunction of chaperones and nuclear envelope pathology.

The neuronal ceroid-lipofuscinoses (Batten disease) collectively constitute one of the most common groups of inherited childhood onset neurodegenerative disorders, and have also been identified in many domestic and laboratory animals. The group of human neuronal ceroid-lipofuscinoses currently comprises 14 genetically distinct disorders, mostly characterised by progressive mental, motor and visual deterioration with onset in childhood or adolescence. Abnormal autofluorescent, electron-dense granules accumulate in the cytoplasm of nerve cells, and this storage process is associated with selective destruction and loss of neurons in the brain and retina. The present paper outlines nearly 200years of clinical, neuropathological, biochemical and molecular genetic research, gradually leading, since 1995, to the identification of 13 different genes and over 360 mutations that underlie these devastating brain disorders and form the basis of a new classification system. These genes are evidently of vital importance for the normal development and maintenance of cerebral neurons. Elucidation of their functions and interactions in health and disease is a prerequisite for the identification of possible therapeutic targets, but may also further our understanding of the basic mechanisms of neurodegeneration and ageing. An account is also given of the development of international cooperation and free access electronic resources facilitating NCL research. This article is part of a Special Issue entitled: The Neuronal Ceroid Lipofuscinoses or Batten Disease.

In childhood the neuronal ceroid lipofuscinoses (NCL) are the most frequent lysosomal diseases and the most frequent neurodegenerative diseases but, in adulthood, they represent a small fraction among the neurodegenerative diseases. Their morphology is marked by: (i) loss of neurons, foremost in the cerebral and cerebellar cortices resulting in cerebral and cerebellar atrophy; (ii) an almost ubiquitous accumulation of lipopigments in nerve cells, but also in extracerebral tissues. Loss of cortical neurons is selective, indiscriminate depletion in early childhood forms occurring only at an advanced stage, whereas loss of neurons in subcortical grey-matter regions has not been quantitatively documented. Among the fourteen different forms of NCL described to date, CLN1 and CLN10 are marked by granular lipopigments, CLN2 by curvilinear profiles (CVPs), CLN3 by fingerprint profiles (FPPs), and other forms by a combination of these features. Among extracerebral tissues, lymphocytes, skin, rectum, skeletal muscle and, occasionally, conjunctiva are possible guiding targets for diagnostic identification, the precise type of NCL then requiring molecular analysis within the clinical and morphological context. Autosomal-recessive adult NCL has been linked molecularly to different childhood forms, i.e. CLN1, CLN5, and CLN6, whilst autosomal-dominant adult NCL, now designated as CLN4, is caused by a newly identified separate gene, DNAJC5. This article is part of a Special Issue entitled: The Neuronal Ceroid Lipofuscinoses or Batten Disease.

Storage diseases are metabolic multiorgan conditions, which may be divided into lysosomal and nonlysosomal diseases. Disorders of the lysosomal type require electron microscopy for morphological diagnosis. It is the metabolic substrate that determines involvement of the cell type or organ in the individual storage disease, allowing extracerebral biopsies, for instance, in the neuronal ceroid-lipofuscinoses (NCL). A hierarchy of tissues biopsied for diagnosis can be based on easy accessibility: blood lymphocytes, skin, conjunctiva, rectum, skeletal muscle. Lysosomal diseases are divided into vacuolar and nonvacuolar ones. NCL display variegated ultrastructural patterns. Drugs may induce lysosomal storage. Finally, polyglucosan body diseases require attention.

Vici syndrome is a recessively inherited multisystem disorder characterized by callosal agenesis, cataracts, cardiomyopathy, combined immunodeficiency and hypopigmentation. To investigate the molecular basis of Vici syndrome, we carried out exome and Sanger sequence analysis in a cohort of 18 affected individuals. We identified recessive mutations in EPG5 (previously KIAA1632), indicating a causative role in Vici syndrome. EPG5 is the human homolog of the metazoan-specific autophagy gene epg-5, encoding a key autophagy regulator (ectopic P-granules autophagy protein 5) implicated in the formation of autolysosomes. Further studies showed a severe block in autophagosomal clearance in muscle and fibroblasts from individuals with mutant EPG5, resulting in the accumulation of autophagic cargo in autophagosomes. These findings position Vici syndrome as a paradigm of human multisystem disorders associated with defective autophagy and suggest a fundamental role of the autophagy pathway in the immune system and the anatomical and functional formation of organs such as the brain and heart.

The etiopathogenesis of sarcoidosis, a systemic granulomatous disease, still remains obscure. A multitude of organs have been described to be affected in systemic sarcoidosis. Skeletal muscles may also be affected, leading to myalgia and weakness. A workup of the specific immune response with emphasis on the macrophage response is provided herein. Affected muscle tissue from seven patients with systemic sarcoidosis was analyzed and compared with that from seven patients with other myopathies containing macrophagocytic infiltration. Monocytes/macrophages and giant cells in granulomas of muscle tissue from patients with sarcoidosis show a status of alternative activation (M2) based on their expression of CD206, CD301, arginase-1, and suppressor of cytokine signaling-1 as a consequence of a functionally type 2 helper T cell (Th2)-biased cytokine profile. Significant fibrosis and up-regulation of CCL18 were associated with the M2 phenotype of macrophages. Conversely, up-regulated Th1 cytokines did not result in significant classical activation of macrophages (M1), with poor inducible nitric oxide synthase and cyclooxygenase-2 production. Giant cell formation was further associated with up-regulated expression of DNAX-activating protein of 12 kDa (DAP12; gene symbol TYROBP). Functionally, alternative activation of macrophages on the basis of a Th2-biased immune response may induce clinical symptoms and chronic evolution of neuromuscular sarcoidosis. This is the first characterization of Th2-mediated immune mechanisms in neuromuscular sarcoidosis suggesting that a specific macrophage activation status leading to myofibrosis may be a key event in the pathogenesis of this disease.

Objectives: To explore a potential expansion of the phenotypic and genotypic characteristics of Finnish variant late-infantile neuronal ceroid lipofuscinosis (NCL), we screened a collection of 47 patients with clinically diagnosed NCL in whom no molecular diagnosis had been made. Methods: We used PCR amplification of genomic DNA, followed by fluorescent-labeled dideoxy-nucleotide chain termination sequencing and multiplex ligation-dependent probe amplification, to screen our cohort of patients for mutations in CLN5 . We collected ethnic background, clinical, and pathologic information, as available, to clarify the breadth of CLN5 disease expression and to explore possible genotype-phenotype correlations. Results: We identified 10 patients with pathogenic CLN5 mutations, including 11 mutations not previously described: 4 missense, 5 out-of-frame insertion/deletion mutations, and 2 large intragenic deletions. We also documented 3 previously reported CLN5 mutations. The age at disease onset in this cohort is predominantly juvenile rather than late infantile. Importantly, we have identified 2 adult-onset patients who share a common pathogenic allele. The majority of patients presented with motor and visual impairments and not seizures. In those patients with available longitudinal data, most had progressed to global neurodevelopmental and visual failure with seizures within 1 to 4 years. Conclusions: Our study suggests that CLN5 mutations 1) are more common in patients with neuronal ceroid lipofuscinosis (NCL) than previously reported, 2) are found in non-Finnish NCL patients of broad ethnic diversity, and 3) can be identified in NCL patients with disease onset in adult and juvenile epochs. CLN5 genetic testing is warranted in a wider population with clinical and pathologic features suggestive of an NCL disorder.

Myofibrillar myopathies are caused by mutations in desmin, alphaB-crystallin, myotilin, ZASP, and filamin C genes. Since the vast majority of myofibrillar myopathy causing mutations are heterozygous single amino acid substitutions or small in-frame deletions, the pathogenic role of mutant versus wild-type protein cannot be assessed in human skeletal muscle by standard immunodetection techniques. We report on an exceptional desminopathy due to a heterozygous c.735G>C mutation. Immunoblotting detected full-length 53 kDa desmin and a truncated 50 kDa variant in skeletal muscle from three affected patients of two different families. RT-PCR identified three desmin mRNA species encoding for wild-type and two mutant proteins, p.Glu245Asp and p.Asp214_Glu245del. Since previous functional studies on the p.Glu245Asp mutant showed biological properties identical to wild-type desmin, the truncated p.Asp214_Glu245del desmin is the disease-causing mutant. Semiquantitative RT-PCR established a fraction of the truncated desmin mRNA species in a range from 24% to 37%. Initial quantification of corresponding desmin proteins in the muscle biopsy of the index patient of one family indicated a fraction of only 10% of the truncated species. However, serial analyses of different sections from each muscle biopsy revealed a high intra- and interindividual variability of the truncated desmin protein level within a range from 5% to 43%. Desmin assembly studies in vitro have established clear-cut pathogenic ratios of mutant versus wild-type proteins. However, our findings point out a far more complex situation in human skeletal muscle. The heterogeneously distributed mutation load within and between individual specimens, which reflects local differences in the expression and/or turnover of the mutant protein in different areas containing multiple myonuclear domains, renders it impossible to define an exact pathogenic threshold of a specific mutant in vivo.

Transcriptional signal cointegrators associate with transcription factors or nuclear receptors and coregulate tissue-specific gene transcription. We report on recessive loss-of-function mutations in two genes ( TRIP4 and ASCC1 ) that encode subunits of the nuclear activating signal cointegrator 1 (ASC-1) complex. We used autozygosity mapping and whole-exome sequencing to search for pathogenic mutations in four families. Affected individuals presented with prenatal-onset spinal muscular atrophy (SMA), multiple congenital contractures (arthrogryposis multiplex congenita), respiratory distress, and congenital bone fractures. We identified homozygous and compound-heterozygous nonsense and frameshift TRIP4 and ASCC1 mutations that led to a truncation or the entire absence of the respective proteins and cosegregated with the disease phenotype. Trip4 and Ascc1 have identical expression patterns in 17.5-day-old mouse embryos with high expression levels in the spinal cord, brain, paraspinal ganglia, thyroid, and submandibular glands. Antisense morpholino-mediated knockdown of either trip4 or ascc1 in zebrafish disrupted the highly patterned and coordinated process of α-motoneuron outgrowth and formation of myotomes and neuromuscular junctions and led to a swimming defect in the larvae. Immunoprecipitation of the ASC-1 complex consistently copurified cysteine and glycine rich protein 1 (CSRP1), a transcriptional cofactor, which is known to be involved in spinal cord regeneration upon injury in adult zebrafish. ASCC1 mutant fibroblasts downregulated genes associated with neurogenesis, neuronal migration, and pathfinding ( SERPINF1, DAB1, SEMA3D, SEMA3A ), as well as with bone development ( TNFRSF11B, RASSF2, STC1 ). Our findings indicate that the dysfunction of a transcriptional coactivator complex can result in a clinical syndrome affecting the neuromuscular system.

With the advent of enzyme histochemistry and electron microscopy, the new nosographic group of congenital myopathies hailed as ‘‘new myopathies’’ [1] was established, largely based on morphological features in biopsied muscle specimens although clinically early (congenital) onset and mild progression were also attributed to these childhood myopathies. When molecular investigations of patients with hereditary neuromuscular diseases began, earlier classifications based on clinical, morphological, and metabolic criteria started to quake, most conspicuously observed in the group of limb girdle muscular dystrophy or limb girdle muscular syndrome, which now comprise seven autosomal dominant (LGMD1A to G) and twelve autosomal-recessive (LGMD2A to L) forms [2]. With the identification of mutations in the ryanodine receptor-1 in central core disease, molecular-based nosographic re-orientation had reached the nosological group of congenital myopathies [3]. Since then, the molecular spectrumof congenitalmyopathies has become broad and diverse [2] with genetic subtyping and overlap among several classical congenital myopathies. In this issue (pages 433–442), Lehtokari and colleagues have added another piece to the genetic mosaic of congenital myopathies by reporting a mutation in the b-tropomyosin gene TPM2 in a patient with morphological and clinical features of ‘‘cap’’ disease. This paper presents several important aspects: (1) It identifies cap disease as a true genetically defined entity. This nosographic significance of a separate type of congenital myopathy had already been suggested in the very first description by Fidzianska and colleagues in 1981 [4] and subsequently reiterated by her in 2002 [5] when she presented three additional unrelated patients, two of them having been adults at

Dynamin 2 has recently been recognized as a causative gene for the autosomal dominant form of centronuclear myopathy (dominant centronuclear myopathy). Here we report an affected father and daughter with dynamin 2 related AD CNM with predominantly distal onset of weakness. In addition to the diagnostic central location of myonuclei the muscle biopsy also showed core-like structures. Muscle MRI in the lower leg revealed prominent involvement of the soleus, but also of the gastrocnemius and the tibialis anterior whereas in the thigh there was a consistent pattern of selective involvement of adductor longus, semimembranosus, biceps femoris, rectus femoris, and vastus intermedius with relative sparing of vastus lateralis and medialis, sartorius, gracilis, and partly of the semitendinosus. These characteristic findings on muscle MRI confirm similar findings reported for CT imaging in dynamin 2 related dominant centronuclear myopathy and may help to differentiate this disorder from central core disease and other myopathies.

TMEM70 is involved in the biogenesis of mitochondrial ATP synthase and mutations in theTMEM70gene impair oxidative phosphorylation. Herein, we report on pathology and treatment of ATP synthase deficiency in four siblings. A consanguineous family of Roma (Gipsy) ethnic origin gave birth to 6 children of which 4 were affected presenting with dysmorphic features, failure to thrive, cardiomyopathy, metabolic crises, and 3-methylglutaconic aciduria as clinical symptoms. Genetic testing revealed a homozygous mutation (c.317-2A>G) in theTMEM70gene. While light microscopy was unremarkable, ultrastructural investigation of muscle tissue revealed accumulation of swollen degenerated mitochondria with lipid crystalloid inclusions, cristae aggregation, and exocytosis of mitochondrial material. Biochemical analysis of mitochondrial complexes showed an almost complete ATP synthase deficiency. Despite harbouring the same mutation, the clinical outcome in the four siblings was different. Two children died within 60 h after birth; the other two had recurrent life-threatening metabolic crises but were successfully managed with supplementation of anaplerotic amino acids, lipids, and symptomatic treatment during metabolic crisis. In summary,TMEM70mutations can cause distinct ultrastructural mitochondrial degeneration and almost complete deficiency of ATP synthase but are still amenable to treatment.

Myosin storage myopathy (OMIM 608358), a congenital myopathy characterised by subsarcolemmal, hyaline-like accumulations of myosin in Type I muscle fibres, was first described by Cancilla and Colleagues in 1971 [Neurology 1971;21:579–585] in two siblings as ‘familial myopathy with probable lysis of myofibrils in type I muscle fibres'. Two mutations in the slow skeletal myosin heavy chain gene ( MYH7 ) have recently been associated with the disease in other families. We have identified a novel heterozygous Leu1793Pro mutation in MYH7 in DNA from paraffin sections of one of the original siblings. This historical molecular analysis confirms the original cases had myosin storage myopathy.

The neuronal ceroid lipofuscinoses (NCLs) represent a group of neurodegenerative disorders characterised by progressive visual failure, neurodegeneration, epilepsy and the accumulation of an autofluorescent lipopigment in neurons and other cells. The main childhood subtypes are infantile (INCL;CLN1), classical late infantile (LINCL;CLN2) and juvenile NCL (J NCL; CLN3), distinguished on the basis of age of onset, clinical course and ultrastructural morphology, and recently genetic analysis. In addition several variant forms of the disease complex have been described as well as a rare adult onset form. Advances in both genetics and biochemistry have led to the identification of the genes for the three main subtypes of childhood NCL and their corresponding protein products and to mapping of two additional genes for two variant forms. The disease causing genes in both INCL and classical LINCL have been shown to encode lysosomal enzymes whilst the JNCL gene codes for a protein whose function is as yet unknown.

The clinical, pathologic, and genetic findings of a boy with intranuclear nemaline rod myopathy are described. Serial muscle biopsies revealed myocyte nuclei containing inclusions that were immunoreactive for α-actinin and increased with age. Genetic analysis revealed a Val163Leu ACTA1 mutation previously associated with nemaline rod myopathy. Although initially delayed, he has reached all milestones and remains stable. These findings suggest intranuclear rods may increase with time and do not necessarily imply a poor prognosis. Muscle Nerve, 2006

Camptocormia (CC) or pronounced forward flexion of the trunk is a common symptom of Parkinson's disease. We describe 2 patients with probable, respectively possible multiple-system atrophy and CC. Magnetic resonance imaging of the erector trunci showed focal patchy hyperintensities with gadolinium enhancement and muscle biopsy was indicative of variably pronounced focal myositis. CC was progressive and the major handicap for both patients after 1 and 1.5 years of follow-up, respectively. The therapeutic response was poor. Similarities with the dropped-head syndrome suggest that the muscle pathology may be either the primary cause of CC, a focal reaction to the CC posture, or a coincident syndrome of old age.

A 52-year-old man, who had developed distal muscle weakness in legs and arms, was found to have distal muscle atrophy as well as cardiac arrhythmia. His 10-year younger brother developed restrictive cardiomyopathy at the age of 20 years, which required cardiac transplantation at the age of 41 years. Skeletal muscle biopsy specimens of the older brother revealed granulofilamentous material and plaques containing numerous proteins, foremost desmin, as did cardiac biopsy tissue. The explanted heart of the younger brother showed similar protein-rich plaques and granulofilamentous material within cardiac myocytes. A novel heterozygous Glu245Asp (E245D) missense mutation in exon 3 of the desmin gene (DES) at 2q35 was found in the older brother. While clinical data and muscle biopsy pathology of the older brother conform to the nosological spectrum of desminopathies, the early-onset cardiomyopathy, a similar cardiac pathology as in skeletal muscle tissues and a novel missense mutation in the DES gene, enlarge the nosological spectrum of desminopathies.

Few medical disciplines have benefited so enormously from the molecular revolution as myology. Whereas the congenital myopathies have flourished from enzyme histochemistry and electron microscopy, defining individual congenital myopathies by structural abnormalities, genetic research has only recently focused on congenital myopathies. However, a number of congenital myopathies have been molecularly elucidated: central and multiminicore diseases, nemaline myopathy, myotubular myopathy, and congenital myopathy marked by aggregation of proteins, giving rise to the concept of protein aggregate myopathies, to which now desminopathies, α-B crystallinopathies, selenoproteinopathy, myotilinopathy, actinopathies, and myosinopathies belong. Based on recent identification of mutations in respective genes, the principle “from morphology, that is, immunohistochemistry, to molecular analysis” through recognition of certain accrued proteins within muscle fibers and subsequent analysis of their respective genes has resulted in a wealth of genetic data and in reconsidering classification and nosologic interpretation of certain congenital myopathies. This heuristic principle needs to be further applied to other genetically still obscure congenital myopathies. ( J Child Neurol 2005;20:94—101).

The 121st European Neuromuscular Centre (ENMC)sponsored International Workshop on ‘DESMIN and Protein Aggregate Myopathies’, attended by 16 active participants from France, Germany, Poland, Spain, Sweden, the United Kingdom and the USA, was actually the fourth one in a row addressing the pathology of the muscle fibre intermediate filament desmin, its associated and similar diseases, all four [1–3] organized by Michel Fardeau and Hans H. Goebel. In his introduction, the chairman, Hans H. Goebel (Mainz), recorded the evolution of ‘Protein Aggregate Myopathies (PAM)’ which are marked by the accumulation of diverse proteins within muscle fibres as a morphologic hallmark in separate myopathies which now comprise several diverse entities (Table 1). Desmin-related myopathies were first reported as cytoplasmic myopathy, granulofilamentous myopathy [4], spheroid body myopathy [5] and a form of congenital muscular dystrophy [6]. Subsequently, they have been found to have accumulation of desmin as a common morphological denominator but are genetically diverse, comprising desminopathies [7,8] owing to mutations in the desmin gene, a-B crystallinopathy [9–11] owing to mutations in the a-B crystallin gene, recently selenoproteinopathies owing to mutations in the selenoprotein N1 gene [12] and newly, added, myotilinopathies [13]. In addition to desmin, a multitude of fibre proteins accrue to respective inclusions or granulofilamentous material. Only briefly, because belonging to other ENMC Consortia, such as one on ‘Nemaline myopathy’

Desmin-related myopathies (DRMs) are a heterogeneous group of muscle disorders, morphologically defined by intrasarcoplasmic aggregates of desmin. Mutations in the desmin and the alpha-B crystallin genes account for approximately one third of the DRM cases. The genetic basis of the other forms remain unknown, including the early-onset, recessive form with Mallory body-like inclusions (MB-DRMs), first described in five related German patients. Recently, we identified the selenoprotein N gene (SEPN1) as responsible for SEPN-related myopathy (SEPN-RM), a unique early-onset myopathy formerly divided in two different nosological categories: rigid spine muscular dystrophy and the severe form of classical multiminicore disease. The finding of Mallory body-like inclusions in two cases of genetically documented SEPN-RM led us to suspect a relationship between MB-DRM and SEPN1. In the original MB-DRM German family, we demonstrated a linkage of the disease to the SEPN1 locus (1p36), and subsequently a homozygous SEPN1 deletion (del 92 nucleotide -19/+73) in the affected patients. A comparative reevaluation showed that MB-DRM and SEPN-RM share identical clinical features. Therefore, we propose that MB-DRM should be categorized as SEPN-RM. These findings substantiate the molecular heterogeneity of DRM, expand the morphological spectrum of SEPN-RM, and implicate a necessary reassessment of the nosological boundaries in early-onset myopathies.

The introduction and application of molecular techniques have commenced to influence and alter the nosology of congenital myopathies. Long-known entities such as nemaline myopathies, core diseases, and desmin-related myopathies have now been found to be caused by unequivocal mutations. Several of these mutations and their genes have been identified by analyzing aggregates of proteins within muscle fibers as a morphological hallmark as in desminopathy and actinopathy, the latter a subtype among the nemaline myopathies. Immunohistochemistry has played a crucial role in recognizing this new group of protein aggregate myopathies within the spectrum of congenital myopathies. It is to be expected that other congenital myopathies marked by inclusion bodies may turn out to be such protein aggregate myopathies, depending on analysis of individual proteins within these protein aggregates and their association with putative gene mutations.

GNE myopathy is an autosomal-recessive disorder caused by mutations in the GNE gene, encoding the key enzyme in the sialic acid biosynthetic pathway, UDP-N-acetylglucosamine 2-epimerase/N-acetyl mannosamine kinase. We studied 50 Bulgarian Roma patients homozygous for p.I618T, an ancient founder mutation in the kinase domain of the GNE gene, dating before the Gypsy exodus from North West India. The clinical features in the Bulgarian GNE group can be described with disease onset mostly in the third decade, but in individual cases, onset was as early as 10 years of age. The majority of patients had foot drop as the first symptom, but three patients developed hand weakness first. Muscle weakness was early and severe for the tibialis anterior, and minimal or late for quadriceps femoris, and respiratory muscles were only subclinically affected even in the advanced stages of the disease. During a 15-year follow-up period, 32 patients became non-ambulant. The average period between disease onset and loss of ambulation was 10.34 ± 4.31 years, ranging from 3 to 20 years. Our analysis of affected sib pairs suggested a possible role of genetic modifying factors, accounting for significant variation in disease severity.

Objective: To analyze antisynthetase syndrome–associated myositis by modern myopathologic methods and to define its place in the spectrum of idiopathic inflammatory myopathies (IIMs). Methods: Skeletal muscle biopsies from antisynthetase syndrome–associated myositis and other IIMs from different institutions worldwide were analyzed by histopathology, quantitative PCR, and electron microscopy. Results: Myonuclear actin filament inclusions were identified as a unique morphologic hallmark of antisynthetase syndrome–associated myositis. Nuclear actin inclusions were never found in dermatomyositis, polymyositis, sporadic inclusion body myositis, autoimmune necrotizing myopathy associated with signal recognition particle or 3-hydroxy-3-methylglutaryl-coenzyme A reductase autoantibodies, or nonspecific myositis associated with other systemic diseases, harboring myositis-associated autoantibodies, and presenting myofiber necrosis. We show that molecules involved in actin filament formation and actin shuttling mechanisms are altered in antisynthetase syndrome, and may thus be involved in pathologic myonuclear actin aggregation. In addition, we have identified a typical topographic distribution of necrotic myofibers predominantly located at the periphery of muscle fascicles accompanied by inflammation and destruction of the perimysial connective tissue. Conclusion: Antisynthetase syndrome–associated myositis is characterized by distinctive myonuclear actin filament inclusions, including rod formations and a typical necrotizing perimysial myositis. This supports the hypothesis that antisynthetase syndrome–associated myositis is unique and should not be grouped among dermatomyositis, polymyositis, sporadic inclusion body myositis, necrotizing autoimmune myositis, or nonspecific myositis. Classification of evidence: This study provides Class II evidence that for patients with IIMs, the presence of myonuclear actin filament inclusions accurately identifies patients with antisynthetase syndrome–associated myositis (sensitivity 81%, specificity 100%).

The congenital myopathies are a heterogeneous group of neuromuscular disorders defined by distinctive morphologic abnormalities of skeletal muscle with weakness and hypotonia. Clinical presentations range from fetal akinesia and neonatal lethality, to mild weakness with preserved ambulation, lifespan, and reproductive fitness. Intellectual abilities are unaffected and pathology is largely limited to skeletal muscle, although some forms include cardiomyopathy. Congenital myopathies can be broadly categorized into subgroups involving nemaline bodies (“rod myopathies”), central or minicores (“core myopathies”), centronuclear myopathies, and fiber type disproportions. Additional structural myopathies include myofibrillar and protein aggregation myopathies and vacuolar myopathies. More than two dozen different genes are implicated, including ones encoding components of the thin filament (nemaline myopathies), sarcomere (titinopathies), triads (centronuclear and core myopathies), and other structures. Most of these disorders are genetically heterogeneous, and many genes cause more than one clinicopathological presentation, making genetic diagnosis a critical adjunct to traditional clinical and pathological evaluations.

Nemaline myopathy is a clinically and genetically heterogeneous muscle disorder. In the nebulin gene we have detected a number of autosomal recessive mutations. Both autosomal dominant and recessive mutations have been detected in the genes for alpha -actin and alpha -tropomyosin 3. A recessive mutation causing nemaline myopathy among the Old Order Amish has recently been identified in the gene for slow skeletal muscle troponin T. As linkage studies had shown that at least one further gene exists for nemaline myopathy, we investigated another tropomyosin gene expressed in skeletal muscle, the beta -tropomyosin 2 gene. Screening 66 unrelated patients, using single strand conformation polymorphism analysis and sequencing, we found four polymorphisms and two heterozygous missense mutations. Both mutations affect conserved amino acids, and in both cases, the mutant allele is expressed. We speculate that the observed mutations affect the formation of the tropomyosin dimer and its actin-binding properties. (C) 2002 Elsevier Science B.V. All rights reserved

We examined 26 individuals with clinical and electron microscopic signs of late infantile neuronal ceroid lipofuscinosis (LINCL). In 22 cases, we found both pathogenic alleles. Sixteen patients exclusively carried either one or a combination of the two common mutations R208X and IVS5-1G > C. In the remaining cases, four missense mutations could be detected, of which R127Q, N286S, and T353P represent novel, previously not described alleles. A clinical performance score was developed by rating motor, visual, and verbal functions and the incidence of cerebral seizures in 3-month intervals during the course of the disease. A Total Disability Score was derived by summing up the single scores for motor, visual, and verbal functions. The 16 individuals with the two common mutations were grouped together (referred to as standard patients), and the 5th, 50th, and 95th centiles were calculated and graphically depicted over time. The scores for motor function and language ability dropped earliest and progressed very similarly in the standard patients. The performance curves of two children with the N286S mutation slightly diverged from the 95th centile. However, the performance curves of one patient with atypical LINCL carrying the R127Q mutation fell far beyond the 95th centile. The presented performance rating clearly and quantitatively delineates the disease course of the LINCL patients and hence offers a useful tool for clinical evaluation of future therapeutic interventions. In addition, the described performance score system can be applied to other types of neuronal ceroid lipofuscinoses and could be adapted to various other neurodegenerative diseases of childhood.

At the age of five years a male child started to develop a progressive rigid spine, torsion scoliosis, and flexion contractures of his elbows, knees, hips, and ankles owing to severe proximal and distal muscle weakness. He had three muscle biopsies from three different muscles at ages 7, 11, and 14 years, respectively. Myopathologically, these muscle tissues contained numerous inclusions which, at the ultrastructural level, turned out to be reducing bodies and cytoplasmic bodies, often in close spatial proximity. Similar histological inclusions, although not further identified by histochemistry and electron microscopy, were seen in his maternal grandmother's biopsied muscle tissue who had developed weakness of the legs and hands after the age of 50 years. The patient's parents were healthy, but the mother's quadriceps muscle showed an increased spectrum of muscle fibre diameters. Our patient, thus, had a neuromuscular disorder, perhaps familial, presenting as a mixed congenital myopathy, i.e., reducing body myopathy with cytoplasmic bodies, of which the morphological lesions could be consistently documented over several years in his different limb muscles. While other mixed congenital myopathies had shown cores and rods, both related to sarcomeres and thus possibly morphogenetically related, cytoplasmic bodies thought to be related to Z-bands and reducing bodies dissimilar to any muscle fibre constituent do not share any common denominator. Therefore, we suggest that this neuromuscular disorder may be a unique mixed congenital myopathy, either sporadic or genetic. In the latter case, the transmission pattern suggested X-linked recessive inheritance, but an autosomal-dominant transmission with variable penetrance could not be ruled out.

Numerous muscular dystrophies, such as dystrophinopathies, sarcoglycanopathies, and emerino- and laminopathies, are marked by the absence or reduction of mutant transsarcolemmal or nuclear proteins. In addition to these recently identified minus-proteinopathies, there are a growing number of plus-proteinopathies among neuromuscular disorders marked by a surplus or excess of endogenous proteins within muscle fibers of different, i.e., nontranssarcolemmal and nonnuclear types. These proteins are often filamentous; for example, desmin and actin accrue in respective desmin-related myopathies, among which are entities marked by mutant desmin, true desminopathies, and actinopathy, the latter often seen as a subgroup in nemaline myopathies. Desmin-related myopathies consist largely of those marked by desmin-containing inclusions and those characterized by desmin-containing granulofilamentous material. When mutations in the desmin gene can be identified, the mutant desmin is thought to form the major myopathological lesion. Together with desmin, other proteins often accumulate. The spectrum of these proteins is quite diverse and encompasses such proteins as dystrophin, nestin, vimentin, alphaB-crystallin, ubiquitin, amyloid precursor protein, and beta-amyloid epitopes, as well as gelsolin and alpha(1)-antichymotrypsin. Among these associated proteins, one, alphaB-crystallin, has been found mutant in one large family, justifying the term alphaB-crystallinopathy as a separate condition among the desmin-related myopathies. Other proteins accruing with desmin have not yet been identified as mutant in desmin-related myopathies. Mutations in the desmin gene entail missense mutations and small deletions. The formation of mutant actin may lead to aggregates of actin filaments which may or may not be associated with formation of sarcoplasmic and/or intranuclear nemaline bodies. A considerable number of missense mutations in the sarcomeric actin gene ACTA1 have been discovered in patients with nemaline myopathy and also in a few patients without myopathological evidence of nemaline bodies in biopsied skeletal muscle fibres. Apart from alphaB-crystallin, no other proteins coaggregating with actin in actin filament aggregates of actinopathy or the actin mutation type of nemaline myopathy have so far been identified. Two further candidates for protein surplus myopathies are hyaline body myopathy, which is marked by accumulation of granular nonfilamentous material within muscle fibers that is rich in myosin and adenosine triphosphatase activities, and hereditary inclusion body myopathies, which are marked by accumulation of tubulofilaments similar to the helical filaments of Alzheimer neurofibrillary tangles. These tubulofilaments consist of diverse proteins as well, though no mutant protein has yet been discovered. So far, no genes responsible for familial hyaline body and hereditary inclusion body myopathies have been identified. The discovery of mutant proteins, desmin, alphaB-crystallin, and actin, as components of surplus or excess proteins accumulating in muscle fibers in certain neuromuscular conditions is responsible for the recent emergence of this new concept of gene-related protein surplus myopathies.