Indikation und Qualifikationskriterien für die Biopsie und präparative Aufarbeitung von Muskel- und Nervengewebeproben

Biopsien von Skelettmuskeln und peripheren Nerven stellen wichtige Verfahren in der diagnostischen Sicherung einer neuromuskulären Krankheit dar. Da sie jedoch invasiv, das heißt nicht kurativ und auf diagnostische Ziele beschränkt sind, bedürfen sie im Rahmen der Gesamtdiagnostik besonders strenger Indikationskriterien, vor allem wenn andere nicht-invasive Methoden zu einem gleichen diagnostischen Ergebnis führen können. In dem Konsensuspapier werden die Wertigkeit der Muskel- und Nervbiopsien bei entsprechenden neuromuskulären Krankheiten aufgezeigt, Hinweise zur chirurgischen Entnahmetechnik gegeben und die präparativen Verfahren kurz dargestellt, die den heutigen myopathologischen und neuropathologischen Standards in der Aufarbeitung bioptisch entnommener Muskel-oder Nervengewebeproben aufzeigen. Ein wichtiger Grundsatz ist, dass nur von Erfahrenen Biopsien durchgeführt und die entnommenen Gewebe adäquat präparativ bearbeitet werden, um für die Patienten eine optimale diagnostische Auswertung des biopsierten Gewebes zu gewährleisten.

Neuronal ceroid lipofuscinosis (NCL) is caused by the entire deletion of CLN8 in the Alpenländische Dachsbracke dog

Neuronal ceroid lipofuscinoses (NCLs) are inherited lysosomal storage diseases that have been described in a variety of dog breeds, where they are caused by different mutations in different genes. However, the causative gene defect in the breed Alpenländische Dachsbracke remained unknown so far. Here we present two confirmed cases of NCL in Alpenländische Dachsbracke dogs from different litters of the same sire with a different dam harboring the same underlying novel mutation in the CLN8 gene. Case 1, a 2-year-old male Alpenländische Dachsbracke was presented with neurological signs including disorientation, character changes including anxiety states and aggressiveness, sudden blindness and reduction of food intake. Magnetic resonance imaging (MRI) scans showed cerebral atrophy with dilation of all cerebral ventricles, thinning of the intermediate mass of the thalamus and widening of the cerebral sulci. Postmortem examination of the central nervous system (CNS) showed neuronal loss in the cerebral cortex, cerebellum and spinal cord with massive intracellular deposits of ceroid pigment. Additional ceroid-lipofuscin deposits were observed in the enteric nervous system and in macrophages within spleen, lymph nodes and lung. Ultrastructural analyses confirmed NCL with the presence of osmiophilic membrane bounded lamellar-like structures. Case 2, a 1,5-year old female Alpenländische Dachsbracke was presented with progressive generalized forebrain disease including mental changes such as fearful reactions to various kinds of external stimuli and disorientation. The dog also displayed seizures, absence of menace reactions and negative cotton-ball test with normal pupillary light reactions. The clinical and post mortem examination yielded similar results in the brain as in Case 1. Whole genome sequencing of Case 1 and PCR results of both cases revealed a homozygous deletion encompassing the entire CLN8 gene as the most likely causative mutation for the NCL form observed in both cases. The deletion follows recessive inheritance since the dam and a healthy male littermate of Case 1 were tested as heterozygous carriers. This is the first detailed description of CLN8 gene associated NCL in Alpenländische Dachsbracke dogs and thus provides a novel canine CLN8 model for this lysosomal storage disease. The presence of ceroid lipofuscin in extracerebral tissues may help to confirm the diagnosis of NCL in vivo, especially in new dog breeds where the underlying mutation is not known.

CLN5 mutations are frequent in juvenile and late-onset non-Finnish patients with NCL

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.

Familial reducing body myopathy with cytoplasmic bodies and rigid spine revisited: identification of a second LIM domain mutation in FHL1

OBJECTIVE

Reducing body myopathy (RBM) is a rare progressive disorder of muscle characterized by intracytoplasmic inclusions, which stain strongly with menadione-NBT (nitroblue tetrazolium). We recently identified the four and a half LIM domain gene FHL1 located on chromosome Xq26 as the causative gene for RBM. So far eight familial cases and 21 sporadic patients with RBM have been reported in the literature.

METHODS

We ascertained a total of 8 members of a German family initially reported by Goebel et al. as a mixed myopathy with rigid spine myopathy and reducing as well as cytoplasmic bodies. Clinical findings in the original and additional family members have been reviewed. Mutation detection was performed by direct sequencing of FHL1 exons.

RESULTS

We identified a novel mutation (p.C150R) in the second LIM domain of FHL1 in six family members (1 male, 5 females). The male index patient was the most affected member presenting with rigid spine, followed by rapidly progressive muscle weakness. He died from the consequences of respiratory insufficiency at the age of 29.5 years. His sister, mother, grandmother, aunt and female cousin all carried the mutation in the heterozygous state. The sister is clinically unaffected; their mother had myopathic changes in her muscle biopsy, while the grandmother showed first signs of weakness at 50 years of age. The 54-year-old aunt and her daughter are clinically asymptomatic.

CONCLUSION

We report a novel LIM2 domain mutation in FHL1 in a previously reported family with RBM with cytoplasmic bodies and spinal rigidity. While the male index patient was significantly affected, female carriers show varying manifestations and may be asymptomatic, likely reflecting varying degrees of X-inactivation. RBM continues to be associated with mutations in the LIM2 domain of FHL1. We also confirm our earlier observation that mutations at the N-terminal end of the LIM2 domain seem to be milder compared to mutations seen at the C-terminal part of the domain which cause severe disease even in female carriers.

Protein aggregation in inclusion body myositis, a sporadic form among protein aggregate myopathies, and in myofibrillar myopathies--a comparative study

Protein aggregation has been identified in muscle fibres and, thus, in certain neuromuscular disorders. There are certain similarities between IBM and DRM: midlife or late-onset clinical symptoms, apparently of both sporadic and genetic background, morphologically autophagocytosis by vacuole formation, which is frequent in IBM though rare in DRM, and presence of tubulofilamentous aggregates, which is almost regular in IBM but scantily found in DRM as beta-amyloid components have been identified as accruing proteins, both in IBM and DRM. Previous studies pointed to the hypothesis that clear morphological borders between the two types of diseases--hereditary inclusion body myopathies/myositis and desmin-related myopathies may not exist. Therefore, we analysed and morphologically characterised the spectrum of proteins accumulating in both types of disorders in order to compare them and more clearly define similarities and dissimilarities between these two different groups of protein aggregate myopathies. Previous studies showed that there is an overlap among some of the proteins accruing in these diseases, but there might also be differences in that a large number of proteins found aggregated in desmin-related myopathies had not yet been described in IBM. The aim of describing the comparative protein profiles is to give more insights into the mechanism of protein aggregation within muscle fibres.

MATERIAL & METHODS

We studied diagnostic muscle biopsies from 10 sIMB patients and 6 MM patients with histological, histochemical, enzyme histochemical, ultrastructural and immunohistochemical techniques using a large number of antibodies.

RESULTS

We noticed a partial overlap of protein expression in the two cohorts of patients for sarcomeric, chaperone and mostly for cytoskeletal proteins. In both of the cohorts, the nuclear proteins were absent in the cytoplasmic bodies. A different pattern of immunolabelling was noted for trans-sarcolemmal proteins, constantly enhanced in the inclusion bodies in MM, but never found in IBM, except for delta-sarcoglycan, dysferlin and caveolin.

CONCLUSIONS

The partial overlap among some of the proteins accruing in these diseases raise the hypothesis that clear nosological borders between s-IBM and MM may not always exist. There are also dissimilarities in the pattern of protein aggregation, suggesting that other additional factors are involved in the pathogenesis.

Consequences of mutations within the C terminus of the FHL1 gene

BACKGROUND

Mutations in the four-and-a-half LIM domain 1 gene (FHL1) cause X-linked late-onset scapuloaxioperoneal myopathy characterized by postural muscle atrophy with rigid spine syndrome with pseudoathleticism/hypertrophy (XMPMA), reducing body myopathy (RBM), and scapuloperoneal myopathy. Divergences in these diseases are hitherto unclear; therefore, we searched for additional families to elucidate differences and similarities of these allelic FHL1opathies.

METHODS

Using genotyping and phenotyping (mutational analysis, muscle histopathology, and Western blotting) we characterized 10 affected men and 8 women from 7 families.

RESULTS

All patients displayed the XMPMA phenotype. In 1 family with a novel missense mutation, 2 affected men had an aneurysm of the sinus of Valsalva in addition. In 5 affected men and 2 affected women from 4 families, the C224W missense mutation in FHL1 was detected, which putatively disrupts the fourth LIM domain. In 3 other families with 5 affected men and 1 female, 2 novel missense variants and a novel splice-site mutation in the C terminus of FHL1 were found. Muscle morphology revealed mild to moderate degenerative myopathy with myofiber hypertrophy of both fiber types at younger age and cytoplasmic bodies in the majority of the samples. Reducing bodies, pathognomonic for RBM, were not found. Western blotting revealed no detectable FHL1A protein in our patients.

CONCLUSIONS

As a consequence of C terminal FHL1 gene mutations, the X-linked myopathy characterized by postural muscle atrophy (XMPMA) phenotype and morphotype with cytoplasmic bodies are found. In the spectrum of FHL1opathies, the preserved FHL1C protein is likely responsible for the moderate XMPMA phenotype compared with the more severe reducing body myopathy/scapuloperoneal myopathy phenotype.

Macrophagic myofasciitis plus (distinct types of muscular dystrophy)

Macrophagic myofasciitis (MMF) is a well-known lesion following vaccination with aluminium-containing vaccines. It has abundantly been reported in adults and several times in children, often in single patients or in rather small cohorts. Only few of these published reports on children have shown distinct myopathology of another neuromuscular disease except for MMF. Indications for biopsy often were nondescript clinical features in children, such as hypotonia or delay in motor development but, apparently, never that of suspected MMF. Thus, in previous reports as well as in our two patients, encountering MMF in the biopsied tissue specimens was coincidental. Our two unrelated patients with MMF also had two separate types of muscular dystrophy, a merosinopathy and dystrophinopathy, showing a combination of myopathologically well-defined neuromuscular diseases, muscular dystrophies and MMF. Detecting such a combination of two separate conditions may, in the future, be rare when non-invasive techniques, e. g., genetic, will have replaced muscle biopsy in ascertaining hereditary neuromuscular conditions, especially in children.

[Congenital and other myopathies]

The myopathies presented here fall into two groups: Congenital myopathies and protein aggregate myopathies. These genetic conditions often require all modern diagnostic investigations, including histology, enzyme histochemistry, immunohistochemistry and electron microscopy to pave the way to an adequate individual molecular analysis and diagnosis. This is necessary to provide the patient and his or her family information about disease-characteristics or even disease-specific features. Distal myopathies, although caused by mutations in different genes, and toxic myopathies as acquired neuromuscular conditions largely provide non-specific morphological features a correct nosological interpretation of which only succeeds with additional non-morphological data.

Congenital myopathies--a comprehensive update of recent advancements

The congenital myopathies are relatively newly discovered compared with other categories of muscle diseases. Current research continues to clarify and classify the congenital myopathies. These pose a diagnostic problem and cannot be diagnosed by routine hematoxylin and eosin stain. A lot of special techniques are required to diagnose them correctly and it's various subtypes. The disease specific structural changes seen in the muscle are detected by enzyme histochemistry, immunohistochemistry and electron microscopy. Through this review we provide an up-to-date analysis of congenital myopathies including clinical and pathologic aspects.

A mutation in myotilin causes spheroid body myopathy

BACKGROUND

Spheroid body myopathy (SBM) is a rare, autosomal dominant, neuromuscular disorder, which has only been previously reported in a single large kindred. Identification of the mutated gene in this disorder may provide insight regarding abnormal neuromuscular function.

METHODS

The authors completed a detailed clinical evaluation on an extensive kindred diagnosed with SBM. Genome-wide linkage analysis was performed to localize the disease gene to a specific chromosomal region. Further marker genotyping and screening of a positional, functional candidate gene were completed to detect the disease-causing mutation. Pathologic analysis of muscle biopsy was performed on three individuals. Biochemical studies were performed on one muscle biopsy specimen from an affected individual.

RESULTS

Linkage to chromosome 5q23-5q31 was detected with a lod score of 2.9. Genotyping of additional markers in a larger sample of family members produced a maximum lod score of 6.1 and narrowed the critical interval to 12.2 cM. Screening of the candidate gene titin immunoglobulin domain protein (TTID, also known as MYOT) detected a cytosine-to-thymine mutation in exon 2 of all clinically affected family members. Similar pathologic changes were present in all muscle biopsy specimens. Immunohistologic and biochemical analysis revealed that the TTID protein, also known as myotilin, is a component of the insoluble protein aggregate.

CONCLUSIONS

A novel mutation in the TTID gene results in the clinical and pathologic phenotype termed "spheroid body myopathy." Mutations in this gene also cause limb-girdle muscular dystrophy 1A and are associated with myofibrillar myopathy.

The neuronal ceroid-lipofuscinoses. Recent advances

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 (JNCL;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.

Congenital myopathies

Most congenital myopathies have been defined on account of the morphological findings in enzyme histochemical preparations. In effect, the diagnosis of this group of diseases continues to be made on the histological pattern of muscle biopsies. However, progress has been made in elucidating the molecular genetic background of several of the congenital myopathies. In this updated review we address those congenital myopathies for which gene defects and mutant proteins have been found (central core disease, nemaline myopathies, desminopathy, actinopathy, certain vacuolar myopathies, and myotubular myopathy) and the other disease with central nuclei (centronuclear myopathy).

Protein aggregate myopathies

Protein aggregate myopathies (PAM) are an emerging group of muscle diseases characterized by structural abnormalities. Protein aggregate myopathies are marked by the aggregation of intrinsic proteins within muscle fibers and fall into four major groups or conditions: (1) desmin-related myopathies (DRM) that include desminopathies, a-B crystallinopathies, selenoproteinopathies caused by mutations in the, a-B crystallin and selenoprotein N1 genes, (2) hereditary inclusion body myopathies, several of which have been linked to different chromosomal gene loci, but with as yet unidentified protein product, (3) actinopathies marked by mutations in the sarcomeric ACTA1 gene, and (4) myosinopathy marked by a mutation in the MYH-7 gene. While PAM forms 1 and 2 are probably based on impaired extralysosomal protein degradation, resulting in the accumulation of numerous and diverse proteins (in familial types in addition to respective mutant proteins), PAM forms 3 and 4 may represent anabolic or developmental defects because of preservation of sarcomeres outside of the actin and myosin aggregates and dearth or absence of other proteins in these actin or myosin aggregates, respectively. The pathogenetic principles governing protein aggregation within muscle fibers and subsequent structural sarcomeres are still largely unknown in both the putative catabolic and anabolic forms of PAM. Presence of inclusions and their protein composition in other congenital myopathies such as reducing bodies, cylindrical spirals, tubular aggregates and others await clarification. The hitherto described PAMs were first identified by immunohistochemistry of proteins and subsequently by molecular analysis of their genes.

Diagnostic immunohistochemistry in neuromuscular disorders

Most neuromuscular disorders display only non-specific myopathological features in routine histological preparations. However, a number of proteins, including sarcolemmal, sarcomeric, and nuclear proteins as well as enzymes with defects responsible for neuromuscular disorders, have been identified during the past two decades, allowing a more specific and firm diagnosis of muscle diseases. Identification of protein defects relies predominantly on immunohistochemical preparations and on Western blot analysis. While immunohistochemistry is very useful in identifying abnormal expression of primary protein abnormalities in recessive conditions, it is less helpful in detecting primary defects in dominantly inherited disorders. Abnormal immunohistochemical expression patterns can be confirmed by Western blot analysis which may also be informative in dominant disorders, although its role has yet to be established. Besides identification of specific protein defects, immunohistochemistry is also helpful in the differentiation of inflammatory myopathies by subtyping cellular infiltrates and demonstrating up-regulation of subtle immunological parameters such as cell adhesion molecules. The role of immunohistochemistry in denervating disorders, however, remains controversial in the absence of a reliable marker of muscle fibre denervation. Nevertheless, as well as the diagnostic value of immunocytochemical analysis it may also widen understanding of muscle fibre pathology as well as help in the development of therapeutic strategies.

Myosin storage myopathy: Slow skeletal myosin (MYH7) mutation in two isolated cases

Myosin storage myopathy is a congenital myopathy characterized by subsarcolemmal hyaline bodies in type 1 muscle fibers, which are ATPase positive and thus contain myosin. Mutations recently were identified in the type 1 muscle fiber myosin gene (MYH7) in Swedish and Saudi families with myosin storage myopathy. The authors have identified the arginine 1845 tryptophan mutation found in the Swedish families in two isolated Belgian cases, indicating a critical role for myosin residue arginine 1845.

Desmin myopathy

Desmin myopathy is a recently identified disease associated with mutations in desmin or alphaB-crystallin. Typically, the illness presents with lower limb muscle weakness slowly spreading to involve truncal, neck-flexor, facial, bulbar and respiratory muscles. Skeletal myopathy is often combined with cardiomyopathy manifested by conduction blocks and arrhythmias resulting in premature sudden death. Sections of the affected skeletal and cardiac muscles show abnormal fibre areas containing amorphous eosinophilic deposits seen as granular or granulofilamentous material on electron microscopic examination. Immuno-staining for desmin is positive in each region containing abnormal structures. The inheritance pattern in familial desmin myopathy is autosomal dominant or autosomal recessive, but many cases have no family history. At least some, and probably most, non-familial desmin myopathy cases are associated with de novo desmin mutations. Age of disease onset and rate of progression may vary depending on the type of inheritance and location of the causative mutation. Multiple mutations have been identified in the desmin gene: point substitutions, insertion, small in-frame deletions and a larger exon-skipping deletion. The majority of these mutations are located in conserved alpha-helical segments of desmin. Many of the missense mutations result in changing the original amino acid into proline, which is known as a helix breaker. Studies of transfected cell cultures indicate that mutant desmin is assembly-incompetent and able to disrupt a pre-existing filamentous network in dominant-negative fashion. Disease-associated desmin mutations in humans or transgenic mice cause accumulation of chimeric intracellular aggregates containing desmin and other cytoskeletal proteins. alphaB-crystallin serves in the muscle as a chaperone preventing desmin aggregation under various forms of stress. If mutated, alphaB-crystallin may cause a myopathy similar to those resulting from desmin mutations. Routine genetic testing of patients for mutations in desmin and alphaB- crystallin genes is now available and necessary for establishing an accurate diagnosis and providing appropriate genetic counselling. Better understanding of disease pathogenesis would stimulate research focused on developing specific treatments for these conditions.

[Fabry's disease: new therapeutic options for this lysosomal storage disorder]

Fabry's disease is an x-linked, recessive, lysosomal storage disorder that results from deficient alpha-galactosidase A activity with pathological sphingolipid deposition mainly in endothelium, smooth muscle cells, kidneys, central and peripheral nervous system, and myocardium. Clinical manifestation mostly occurs during childhood and adolescence with severe pain attacks or chronic pain mainly in hands and feet, hypohydrosis, and skin lesions (angiokeratoma). In more advanced disease stages, renal and cerebrovascular complications develop with proteinuria and later renal failure and cerebral ischemia caused by cerebral microangiopathy, dilatative arteriopathy, or cardiac embolism. Heterozygote female carriers are severely affected more often than was previously considered. The diagnosis is based on the detection of deficient alpha-galactosidase A activity in leukocytes, fibroblasts, or tissue biopsies. Two randomised placebo-controlled studies showed that enzyme replacement is effective by demonstrating either reduced pain or reduced tissue sphingolipid deposition. Early diagnosis of Fabry's disease is important in view of these new causal therapeutic options.

Classical infantile spinal muscular atrophy with SMN deficiency causes sensory neuronopathy

OBJECTIVE

Classic infantile spinal muscular atrophy (SMA) is believed to be a purely motor disorder, affecting neurons of the spinal anterior horn and nuclei of the lower cranial nerves. Other organ malformations or peripheral nerve involvement have been regarded as exclusion criteria for infantile SMA. Whether SMN protein deficiency can also lead to loss of sensory neurons has not been systematically addressed.

METHODS

The authors evaluated the sural nerve biopsies of 19 patients with infantile SMA of varying severity. The diagnosis of SMA was confirmed by the presence of a homozygous deletion of the SMN1 gene in all patients.

RESULTS

In seven unrelated infants with SMA type I, axonal degeneration of the sural nerve was noted. Five patients showed abnormal sensory conduction, thus prompting sural nerve biopsy. Sural nerves showed different degrees of axonal loss: fiber density ranged from 3.482 to 22.076/mm2 and was markedly reduced in four patients. There was no evidence of primary demyelination: the ratio of total myelinated fiber thickness to axon diameter (g-ratio) was normal in the patients examined. In seven patients with SMA II and five patients with SMA III, no sural nerve alterations were seen, and conduction velocity was normal. In addition to SMN1 gene deletions, homozygous NAIP gene deletions were detected in six out of seven infants with peripheral neuropathy, whereas there was no evidence of a large deletion including the multicopy markers C212 and Ag1-CA in two out of three families tested.

CONCLUSIONS

In this series of patients with SMA I through III who underwent sural nerve biopsy, there was significant sensory nerve pathology in severely affected patients with SMA type I, whereas there were no sensory nerve alterations clinically or morphologically in patients with milder SMA type II or III.

Filamin C accumulation is a strong but nonspecific immunohistochemical marker of core formation in muscle

Filamin C is the muscle isoform of a group of large actin-crosslinking proteins. On the one hand, filamin C is associated with the Z-disk of the myofibrillar apparatus and binds to myotilin; on the other hand, it interacts with the sarcoglycan complex at the sarcolemma. Filamin C may be involved in reorganizing the cytoskeleton in response to signalling events and in muscle it may, in addition, fulfill structural functions at the Z-disk. An examination of biopsies from patients with multi-minicore myopathy, central core myopathy and neurogenic target fibers with core-like target formations (TF) revealed strong reactivity of all the cores and target formations with two different anti-filamin C antibodies. In all three conditions, the immunoreactivity in the cores for filamin C was considerably stronger than that for desmin. Only for alphaB-crystallin were comparable levels of immunoreactivity detected. There was no difference in intensity for filamin C between the three pathological conditions. Thus, filamin C along with alphaB-crystallin is a strong and robust, but nonspecific marker of core formation. The reason why filamin C accumulates in cores is unclear at present, but we postulate that it may be critically involved in the chain of events eventually leading to myofibrillar degeneration.

Mucolipidosis IV: novel mutation and diverse ultrastructural spectrum in the skin

Mucolipidosis IV, a severe neurologic and ophthalmologic progressive disorder has a clinical range of onset between early childhood and adolescence entailing clinically severe, moderate, and mild forms, all of them majorly affecting Ashkenazi Jewish patients in an autosomal-recessive fashion owing to mutations in the MCOLN1 gene which encodes a transmembrane protein called mucolipin 1. We report on one of two affected siblings, the older brother having died of ML IV at the age of 33 years, the younger recently at the age of 37 years. Biopsied skin disclosed several types of lysosomal residual bodies, membrane-bound vacuoles, avacuolar lamellar bodies resembling membraneous cytoplasmic bodies, and a diverse spectrum of lipopigments which include curvilinear and fingerprint profiles. Contrary to earlier reports, disease-specific lysosomal residual bodies could not be identified in circulating lymphocytes of our patient. Mutation analysis revealed a homozygous novel mutation of a 34 bp deletion and 3 bp insertion in exon 2 of the MCOLN1 gene, perhaps the reason for this unusual clinical and morphological phenotype.

A G468-T AMPD1 mutant allele contributes to the high incidence of myoadenylate deaminase deficiency in the Caucasian population

Myoadenylate deaminase deficiency is the most common metabolic disorder of skeletal muscle in the Caucasian population, affecting approximately 2% of all individuals. Although most deficient subjects are asymptomatic, some suffer from exercise-induced myalgia suggesting a causal relationship between a lack of enzyme activity and muscle function. In addition, carriers of this derangement in purine nucleotide catabolism may have an adaptive advantage related to clinical outcome in heart disease. The molecular basis of myoadenylate deaminase deficiency in Caucasians has been attributed to a single mutant allele characterized by double C to T transitions at nucleotides +34 and +143 in mRNA encoded by the AMPD1 gene. Polymerase chain reaction-based strategies have been developed to specifically identify this common mutant allele and are considered highly sensitive. Consequently, some laboratories preferentially use this technique over other available diagnostic tests for myoadenylate deaminase deficiency. We previously identified a G468-T mutation in one symptomatic patient who was only heterozygous for the common AMPD1 mutant allele. In this report, nine additional individuals with this compound heterozygous genotype are revealed in a survey of 48 patients with documented deficiency of skeletal muscle adenosine monophosphate deaminase and exercise-induced myalgia. Western blot analysis of leftover biopsy material from one of these individuals does not detect any immunoreactive myoadenylate deaminase polypeptide. Baculoviral expression of the G468-T mutant allele produces a Q156H substitution enzyme exhibiting labile catalytic activity. These combined results demonstrate that the G468-T transversion is dysfunctional and further indicate that AMPD1 alleles harboring this mutation contribute to the high incidence of partial and complete myoadenylate deaminase deficiency in the Caucasian population. Consequently, genetic tests for abnormal AMPD1 expression designed to diagnose patients with metabolic myopathy, and to evaluate genetic markers for clinical outcome in heart disease should not be based solely on the detection of a single mutant allele.

A sporadic case of rippling muscle disease caused by a de novo caveolin-3 mutation

OBJECTIVE

To determine the cause of sporadic rippling muscle disease (RMD) in a 24-year-old patient.

BACKGROUND

RMD is a rare myopathy characterized by percussion-induced rapid muscle contractions (PIRC), muscle mounding, and rippling waves. We have recently found that autosomal dominant RMD is caused by mutations in the caveolin-3 gene (CAV3) on chromosome 3p25. Possibly, increased activity of neuronal nitric oxide synthase (nNOS) contributes to the clinical characteristics of increased mechanical muscle hyperexcitability.

METHODS

Clinical examination, mutational analysis, and immunohistochemistry of muscle tissue were performed in a patient with sporadic RMD.

RESULTS

The authors observed a de novo CAV3 missense mutation Arg26Gln. Immunohistochemistry showed reduced caveolin-3 surface expression in a muscle biopsy. In addition, the authors found normal sarcolemmal nNOS expression and a reduced expression of alpha-dystroglycan in muscle fibers.

CONCLUSIONS

These data confirm that RMD is caused by CAV3 mutations. Moreover, there is evidence that CAV3 mutations may also be found in patients without a positive family history of RMD.

Neuronal ceroid lipofuscinosis: late infantile or Jansky Bielschowsky type--re-revisited

Among the now eight genetic types of neuronal ceroid-lipofuscinoses (NCL), CLN1 to CLN8, CLN2 is considered classic late-infantile NCL. It was originally described by Jansky in a family of eight children with four of them affected [Jansky J (1908) Sborn Lék 13:165-196] and, subsequently, by Bielschowsky in a family of three children each of whom was affected, and, hence, termed Jansky-Bielschowsky type of NCL. Earlier, archival studies of Bielschowsky's original post-mortem tissue blocks had documented accumulation of autofluorescent lipopigments with a curvilinear ultrastructure. In a subsequent study, described here, immunohistochemical absence of the CLN2-related lysosomal enzyme tripeptidyl peptidase-I and two heterozygous mutations in the CLN2 gene could be demonstrated in these archival tissues, further corroborating the identity of Bielschowsky's familial disorder and CLN2 described by M. Bielschowsky at the beginning of the last century. Furthermore, these immunohistochemical and mutational investigations underscore the value of archival tissue studies.

Reducing body myopathy with cytoplasmic bodies and rigid spine syndrome: a mixed congenital myopathy

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.

[Keratopathy as a sign of multifocal congenital sensory polyneuropathy. A case report]

PATIENT

A 63-year-old female with bilateral recurrent corneal ulcerations for 10 years, suffered from vascularisation of the cornea and absence of corneal sensitivity. Other symptoms were multifocal hypoaesthesia with hypalgesia of hands and legs, generalised lack of deep tendon reflexes, absence of somato-sensory evoked potentials (SSEP) and of sensory nerve action potentials (SNAP) in these regions. A sural biopsy demonstrated extreme lack of myelinated fibres. Acquired causes for polyneuropathy were excluded.

THERAPY

Subsequent to local ocular treatment we carried out a perforating corneal transplantation of the left eye because of corneal scars. This had to be repeated 2 years later because of vascularisation of the transplant. The visual function of the left eye could be stabilised at values between 0.2 and 1/50.

CONCLUSION

Anamnesis and clinical symptoms of the patient are compatible with the diagnosis of hereditary sensory neuropathy type II (HSN II) affecting the trigeminal nerves. In patients with neuropathy and impaired corneal sensitivity, a favourable prognosis may be achieved by a corneal transplant.

Morphological aspects of the neuronal ceroid lipofuscinoses

Morphological aspects of the neuronal ceroid lipofuscinoses (NCL) encompass two main features: loss of nerve cells and accumulation of autofluorescent lipopigments within cellular compartments. The former requires histology and morphometry for assessment, while the latter necessitates fluorescence microscopy, electron microscopy, and immunohistochemistry. Accumulation of lipopigments is widespread throughout the central nervous system and extracerebrally. The latter feature enables diagnosis of NCL and its clinical subtype. Loss of neurons is most pronounced in cerebral and cerebellar cortices, in early childhood forms. In subcortical grey matter and in later-onset forms, juvenile and adult NCL, reduction in neurons and possible preceding dendritic pathology may only correctly be ascertained by age-matched, controlled morphometric investigations which, to date, have not yet completely assessed subcortical neuronal damage. Presently, clinical and morphological evaluations are mandatory for genetic analysis, genetic counselling, and prenatal diagnosis, the latter often being based on combined genetic and morphological studies.

Fulminant course in a case of diffuse myelinoclastic encephalitis-- a case report

We report on a 10-year old previously healthy boy who exhibited a fulminant and nearly monophasic clinical course of demyelinating encephalitis with relapsing intracranial hypertension syndrome. Histologic examination of a diagnostic brain biopsy revealed an inflammatory demyelinating process with perivascular T lymphocytic infiltration and axonal damage reminiscent of multiple sclerosis-like lesions. In the brain, the DNA of human Herpes virus 6 (HHV6) was detectable. Eleven months after the initial symptoms and on maintainance with oral steroids, MRI showed demyelination of both hemispheres as well as demyelination of the brain stem and Wallerian degeneration. The boy exhibited a severe neurologic defect syndrome. The clinical and radiological course is unusual because of the asymmetric progression of the encephalitis and the extensive confluent lesions without demarcated border or enhancement of the rim after injection of gadolinium. The clinical course showed no definite steroid response. The pathogenetic relevance of HHV6 remains elusive. Although single patients with HHV6-associated encephalomyelitis have been reported, HHV6 DNA is occasionally detected in brains of healthy individuals.

Neurodegenerative diseases

This article briefly discusses and illustrates the major important neurodegenerative diseases of adulthood and neurometabolic (neurodegenerative in a broader sense) diseases of childhood and their gross neuropathology. Macroscopic views of the brain including the cerebellum and the brain stem and the spinal cord are given by external inspection as well as gross sections after brain cutting. Histologic details and photographs are supplied to explain and corroborate certain gross findings. This article attempts to correlate nosologic and neuropathologic features as the basis for interpreting neuroimaging data.

Surplus protein myopathies

Certain muscular dystrophies are marked by absence or reduction of mutant proteins, foremost dystrophinopathies and sarcoglycanopathies. Conversely, other sporadic and familial neuromuscular conditions are marked by a surplus of proteins present in a granular or filamentous form, such as desmin-related myopathies, actinopathy and, perhaps, hyaline body myopathy. This emerging group of congenital myopathies is clinically, immunohistochemically, and genetically diverse. Clinically, early- and late-onset diseases with variable courses are described. Immunohistochemically, mutant gene-related and other proteins have been identified by immunohistochemistry. Mutations in the desmin and alpha-B crystallin genes have been discovered in desminopathies. Mutations in the actin gene, but in no other genes have been revealed in actinopathy. Surplus sarcoplasmic and/or intranuclear nemaline bodies have been related to mutant tropomyosin-3, actin and nebulin genes. This emerging concept of surplus protein myopathies will require substantial investigation to further interpret the results of present and future studies.

Morphological studies on CLN2

Electron microscopic, fluorescence microscopic, and immunohistochemical studies earlier performed on archival cerebral tissue from Max Bielchowsky's original three patients revealed curvilinear bodies rich in subunit C of mitochondrial ATP synthase (SCMAS). Recent progress in the elucidation of CLN2, i.e. identification of the defective lysosomal enzyme tripeptidyl-peptidase I (TPP-I) and mutations in the CLN2 gene have further corroborated earlier data. Immunohistochemically the absence of the TPP-I protein could be confirmed in the archival tissues using pathological controls. Unlike biochemistry, immunohistochemistry enables examination of these archival tissues elucidating the causative defect. Complementary molecular studies identified mutations in the CLN2 gene in the archival tissues and thereby convincingly demonstrated that these three children truly had classic late infantile neuronal ceroid lipofuscinosis (LINCL), now called CLN2. This archival study documents the possibilities to revalidate disease-specific original nosologic reports. Chloroquine is toxic to lysosomal enzymes and results in lysosomal storage. The material is autofluorescent and gives the ultrastructural pattern of curvilinear profiles, thus resembling classic late infantile NCL, representing a good experimental model. In humans chloroquine therapy may cause a myopathy (and retinopathy) and, as recently suggested, an encephalopathy marked by lysosomal accretion in several cell types including neurons. Immunohistochemically, SCMAS also accumulates, further strengthening morphologic similarity between LINCL and human chloroquine intoxication.

Secondary reduction in calpain 3 expression in patients with limb girdle muscular dystrophy type 2B and Miyoshi myopathy (primary dysferlinopathies)

Dysferlin is the protein product of the gene (DYSF) that is defective in patients with limb girdle muscular dystrophy type 2B and Miyoshi myopathy. Calpain 3 is the muscle-specific member of the calcium activated neutral protease family and primary mutations in the CAPN3 gene cause limb girdle muscular dystrophy type 2A. The functions of both proteins remain speculative. Here we report a secondary reduction in calpain 3 expression in eight out of 16 patients with a primary dysferlinopathy and clinical features characteristic of limb girdle muscular dystrophy type 2B or Miyoshi myopathy. Previously CAPN3 analysis had been undertaken in three of these patients and two showed seemingly innocuous missense mutations, changing calpain 3 amino acids to those present in the sequences of calpains 1 and 2. These results suggest that there may be an association between dysferlin and calpain 3, and further analysis of both genes may elucidate a novel functional interaction. In addition, an association was found between prominent expression of smaller forms of the 80 kDa fragment of laminin alpha 2 chain (merosin) and dysferlin-deficiency.

Desmin splice variants causing cardiac and skeletal myopathy

Desmin myopathy is a hereditary or sporadic cardiac and skeletal myopathy characterised by intracytoplasmic accumulation of desmin reactive deposits in muscle cells. We have characterised novel splice site mutations in the gene desmin resulting in deletion of the entire exon 3 during the pre-mRNA splicing. Sequencing of cDNA and genomic DNA identified a heterozygous de novo A to G change at the +3 position of the splice donor site of intron 3 (IVS3+3A-->G) in a patient with sporadic skeletal and cardiac myopathy. A G to A transition at the highly conserved -1 nucleotide position of intron 2 affecting the splice acceptor site (IVS2-1G-->A) was found in an unrelated patient with a similar phenotype. Expression of genomic DNA fragments carrying the IVS3+3A-->G and IVS2-1G-->A mutations confirmed that these mutations cause exon 3 deletion. Aberrant splicing leads to an in frame deletion of 32 complete codons and is predicted to result in mutant desmin lacking 32 amino acids from the 1B segment of the alpha helical rod. Functional analysis of the mutant desmin in SW13 (vim-) cells showed aggregation of abnormal coarse clumps of desmin positive material dispersed throughout the cytoplasm. This is the first report on the pathogenic potentials of splice site mutations in the desmin gene.

Ultrastructure of the retina in adult neuronal ceroid lipofuscinosis

A 33-year-old woman died of biopsy-proven adult neuronal ceroid lipofuscinosis (NCL) or Kufs' disease marked by fingerprint and curvilinear lipopigments in neural and nonneural cell types. She had never experienced visual impairment or shown electroretinographic abnormalities. At autopsy, her retina appeared intact without degeneration at the light-microscopic level, but nerve cells in different layers were loaded with lipopigments of the granular type. This appears to be the third ultrastructural study of the retina in a patient with adult NCL, a former one showing preservation of the retina, another retinal degeneration. Thus, only further molecular genetic data will clarify the nosology of adult NCL with and without retinal degeneration.

Progress in desmin-related myopathies

Desmin-related myopathies are sporadic and familial neuromuscular conditions of considerable clinical heterogeneity uniformly marked by the pathologic accretion of desmin, often in a filamentous fashion. A large variety of other proteins, some of them cytoskeletal, also accrue. Morphologically, two types may be distinguished, one characterized by inclusions such as cytoplasmic and spheroid bodies or desmin-dystrophin plaques and another marked by granulofilamentous material. The genetic spectrum of desmin-related myopathies is quite diverse in that missense mutations and deletions in the desmin gene and a missense mutation in the alpha-B crystallin gene have been detected and several genes on other chromosomes have been mapped; the encoded protein products of these genes, however, are unknown. Accumulation of desmin and other proteins appears to be due to impaired nonlysosomal proteolysis. Mutant desmin that appears to be hyperphosphorylated seems to act as a seed protein for filament aggregation, inducing formation of inclusions and granulofilamentous material in these conditions. This condition is part of the group of disorders known as "surplus protein myopathies."

Gene-related protein surplus myopathies

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.

Immunosuppressive treatment of rippling muscles in patients with myasthenia gravis

Rippling muscle disease is a rare autosomal dominant disorder that may occur sporadically. In this report two patients presenting with rippling muscles followed by myasthenia gravis are described. Our first patient developed rippling muscles about 1 month after infection with Yersinia enterocolitica. Two years later myasthenia gravis appeared. Our second patient had a 2-year history of asthma prior to the onset of rippling muscles which preceded the myasthenic symptoms by 4-8 weeks. Acetylcholine receptor and anti-skeletal muscle antibody titers were positive in both patients. In both patients the rippling phenomena worsened with pyridostigmine treatment but markedly improved after immunosuppression with azathioprine.

Mutations in the skeletal muscle alpha-actin gene in patients with actin myopathy and nemaline myopathy

Muscle contraction results from the force generated between the thin filament protein actin and the thick filament protein myosin, which causes the thick and thin muscle filaments to slide past each other. There are skeletal muscle, cardiac muscle, smooth muscle and non-muscle isoforms of both actin and myosin. Inherited diseases in humans have been associated with defects in cardiac actin (dilated cardiomyopathy and hypertrophic cardiomyopathy), cardiac myosin (hypertrophic cardiomyopathy) and non-muscle myosin (deafness). Here we report that mutations in the human skeletal muscle alpha-actin gene (ACTA1) are associated with two different muscle diseases, 'congenital myopathy with excess of thin myofilaments' (actin myopathy) and nemaline myopathy. Both diseases are characterized by structural abnormalities of the muscle fibres and variable degrees of muscle weakness. We have identified 15 different missense mutations resulting in 14 different amino acid changes. The missense mutations in ACTA1 are distributed throughout all six coding exons, and some involve known functional domains of actin. Approximately half of the patients died within their first year, but two female patients have survived into their thirties and have children. We identified dominant mutations in all but 1 of 14 families, with the missense mutations being single and heterozygous. The only family showing dominant inheritance comprised a 33-year-old affected mother and her two affected and two unaffected children. In another family, the clinically unaffected father is a somatic mosaic for the mutation seen in both of his affected children. We identified recessive mutations in one family in which the two affected siblings had heterozygous mutations in two different exons, one paternally and the other maternally inherited. We also identified de novo mutations in seven sporadic probands for which it was possible to analyse parental DNA.