Sarcoglycanopathies in Dutch patients with autosomal recessive limb girdle muscular dystrophy

Within a group of 76 sporadic/autosomal recessive limb girdle muscular dystrophy (LGMD) patients we tried to identify those with LGMD type 2C-E. Muscle biopsy specimens of 40 index patients, who had 22 affected sibs, were analyzed immuno-histochemically for the presence of three subunits: alpha-, beta-, and gamma-sarcoglycans. Abnormal sarcoglycan expression was established in eight patients, with six affected sibs. In one patient gamma-sarcoglycan was absent, and both alpha- and beta-sarcoglycans were reduced. In the remaining seven patients gamma-sarcoglycan was (slightly) reduced, and alpha- and beta-sarcoglycans were absent or reduced. By DNA sequencing mutations were detected in one of the three sarcoglycan genes in all eight cases. Three patients had mutations in the alpha-, three in the beta-, and two in the gamma-sarcoglycan gene. The patients with sarcoglycanopathy comprised the more severely affected cases (P=0.04). In conclusion, sarcoglycanopathy was identified in 23 % (14/62) of the autosomal recessive LGMD patients.

Myopathy in very-long-chain acyl-CoA dehydrogenase deficiency: clinical and biochemical differences with the fatal cardiac phenotype

A 30-year-old man suffered since the age of 13 years from exercise induced episodes of intense generalised muscle pain, weakness and myoglobinuria. Fasting ketogenesis was low, while blood glucose remained normal. Muscle mitochondria failed to oxidise palmitoylcarnitine. Palmitoyl-CoA dehydrogenase was deficient in muscle and fibroblasts, consistent with deficiency of very-long-chain acyl-CoA dehydrogenase (VLCAD). The gene of this enzyme had a homozygous deletion of three base pairs in exon 9, skipping lysine residue 238. Fibroblasts oxidised myristate, palmitate and oleate at a rate of 129, 62 and 38% of controls. In contrast to patients with cardiac VLCAD deficiency, our patient had no lipid storage, a normal heart function, a higher rate of oleate oxidation in fibroblasts and normal free carnitine in plasma and fibroblasts. 31P-nuclear magnetic resonance spectroscopy of muscle showed a normal oxidative phosphorylation as assessed by phosphocreatine recovery, but a significant increase in pH and in Pi/ATP ratio.

Limb girdle muscular dystrophy: a pathological and immunohistochemical reevaluation

Ninety-seven muscle biopsies from 81 limb girdle muscular dystrophy (LGMD) patients [32 autosomal recessive (AR), 15 autosomal dominant (AD), 34 sporadic] were morphologically reevaluated. Sarcoglycan analysis was done in 37 available muscle biopsies of AR and sporadic patients. Chi-square tests were used to analyze the relation between abnormalities in AR/sporadic versus AD cases. Eighty percent of the muscle biopsies showed a predominantly dystrophic pattern, 20% showed myopathic changes, and 17% of these also had neurogenic changes. Muscle histology was not significantly different between AR/sporadic and AD LGMD; however, the observed abnormalities were more pronounced in the AR/sporadic group. Collections of inflammatory cells were observed in 25% and 10% of the AR/sporadic and AD group, respectively. Sarcoglycanopathy was diagnosed in 25% of the AR and sporadic patients of the 37 families tested. We conclude that the histological picture of AR/sporadic and AD LGMD is essentially the same, and sarcoglycanopathy constitutes an important part of the AR/sporadic patients.

The heart in limb girdle muscular dystrophy

OBJECTIVE

To assess the frequency, nature, and severity of cardiac abnormalities in limb girdle muscular dystrophy, and its relation to age and weakness in various genotypes.

DESIGN

In 26 autosomal dominant, 38 autosomal recessive, and 33 sporadic strictly defined patients with limb girdle muscular dystrophy, cardiac evaluation included history, physical examination, chest x ray, electrocardiography, 24 hour ECG Holter monitoring, and echocardiography. In 35 of the 71 autosomal recessive and sporadic cases muscle biopsies were available for sarcoglycan analysis.

MAIN RESULTS

Dilated cardiomyopathy was present in one autosomal dominant case and in three advanced autosomal recessive or sporadic patients, of whom two were found to have alpha sarcoglycan deficiency. Two of these three patients and three other cases showed ECG abnormalities known to be characteristic of the dystrophinopathies. A strong association between the absence of alpha sarcoglycan and the presence of dilated cardiomyopathy was found (p = 0.04). In six autosomal dominant cases there were atrioventricular (AV) conduction disturbances, increasing in severity with age and in concomitant presence of muscle weakness. Pacemaker implantation was necessary in four.

CONCLUSIONS

10% of these patients had clinically relevant cardiac abnormalities. In autosomal dominant limb girdle muscular dystrophy one subtype characterised by muscle weakness and AV conduction disturbances is recognised. In the course of autosomal recessive/sporadic limb girdle muscular dystrophy, dilated cardiomyopathy may develop, probably related to deficiency of dystrophin associated proteins.

A mitochondrial tRNA(Val) gene mutation (G1642A) in a patient with mitochondrial myopathy, lactic acidosis, and stroke-like episodes

We studied a patient with the diagnosis of mitochondrial encephalomyopathy, lactic acidosis, and stroke-like episodes (MELAS) for mitochondrial DNA mutations in muscle. Established MELAS mutations were excluded. Mitochondrial DNA was further analyzed for mutations in the 22 tRNA genes by single-strand conformation polymorphism (SSCP) analysis; a tRNA(Val) mutation (G1642A) was found. The structure of the altered tRNA, the heteroplasmy, and the absence of the mutation in the mother and in 100 control subjects suggests that the tRNA(Val) mutation is associated with the MELAS syndrome.

Miyoshi-type distal muscular dystrophy. Clinical spectrum in 24 Dutch patients

Miyoshi-type distal muscular dystrophy has now been found to be more frequent outside Japan than was previously thought. We studied 24 Dutch patients with Miyoshi-type distal muscular dystrophy and focused on its clinical expression and natural history, muscle CT-scans and muscle biopsy findings. Our study shows that Miyoshi myopathy is a heterogeneous, slowly progressive disorder. The disease starts with weakness and atrophy of the calves and progressively involves the proximal leg and hip muscles and, in a later stage the shoulder and upper arm muscles. After 10 years disease duration, one-third of the patients are dependent on wheelchairs for out-of-door transportation. Disease progression is related to disease duration and not to early age of onset of symptoms. Onset may be at any age and is asymmetrical in roughly half of the cases. Four cases had been initially diagnosed as idiopathic hyper-CK-aemia.

Vocational perspectives and neuromuscular disorders

The present study analyses the actual occupational situation, vocational handicaps and past labour career of a group of about 1000 Dutch patients suffering from a neuromuscular disorder (NMD). On the basis of the likelihood of a substantial employment history and sufficient numbers of patients, four types of NMD were selected: dystrophia myotonica (DM), hereditary motor and sensory neuropathy, (HMSN), spinal muscular atrophy (SMA) and myasthenia gravis (MG). Results show that a labour career is in reach of most NMD patients, even for those with severe limitations. It is concluded that physical limitations seem not to be decisive in that respect. The loss of the quality of communication, the loss of mental abilities and the effect of the diseases on the facial expression, as with some DM patients, are also important for chances on the labour market. Though the labour participation of NMD patients tends to decrease after the age of 34, the availability of work adaptations makes it possible to prolong the labour career. Analysis of the actual work situation of NMD patients shows that both disorder-related limitations and work characteristics play an important role in the amount of physical work problems encountered. It is argued that physical labour has to be regarded as generally unsuitable for NMD patients. This has implications for the sort and level of education to be attained by NMD patients. Career counselling as a focus point for the choice of an educational programme may improve labour market opportunities as well as quality of employment of NMD patients. Allowing for and accepting the possible effects of the disorder in the work situation are considered to be important in respect to labour participation and work satisfaction of workers with NMD. Reducing time pressure demands and increasing the freedom to organize one's work, are measures to be given especial consideration.

Rapid isolation of muscle and heart mitochondria, the lability of oxidative phosphorylation and attempts to stabilize the process in vitro by taurine, carnitine and other compounds

We modified the isolation procedure of muscle and heart mitochondria. In human muscle, this resulted in a 3.4 fold higher yield of better coupled mitochondria in half the isolation time. In a preparation from rat muscle we studied factors that affected the stability of oxidative phosphorylation (oxphos) and found that it decreased by shaking the preparation on a Vortex machine, by exposure to light and by an increase in storage temperature. The decay was found to be different for each substrate tested. The oxidation of ascorbate was most stable and less sensitive to the treatments. When mitochondria were stored in the dark and the cold, the decrease in oxidative phosphorylation followed first order kinetics. In individual preparations of muscle and heart mitochondria, protection of oxidative phosphorylation was found by adding candidate stabilizers, such as desferrioxamine, lazaroids, taurine, carnitine, phosphocreatine, N-acetylcysteine. Trolox-C and ruthenium red, implying a role for reactive oxygen species and calcium-ions in the in vitro damage at low temperature to oxidative phosphorylation. In heart mitochondria oxphos with pyruvate and palmitoylcarnitine was most labile followed by glutamate, succinate and ascorbate. We studied the effect of taurine, hypotaurine, carnitine, and desferrioxamine on the decay of oxphos with these substrates. 1 mM taurine (n = 6) caused a significant protection of oxphos with pyruvate, glutamate and palmitoylcarnitine, but not with the other substrates. 5 mM L-carnitine (n = 6), 1 mM hypotaurine (n = 3) and 0.1 mM desferrioxamine (n = 3) did not protect oxphos with any of the substrates at a significant level. These experiments were undertaken in the hope that the in vitro stabilizers can be used in future treatment of patients with defects in oxidative phosphorylation.

[Peer review in requests for subsidy]

There is peer review by scientific journals and by fund granting institutions. The former is usually a very thorough procedure with the authors being informed of the reasons for rejection of the article, whereas the latter often leaves the applicants with doubts as to the thoroughness and the fairness of the procedure. It is suggested that grant peer review follow the rules for scientific journal peer review including information of the applicants of the referees' findings and opinions. Moreover there is a need for an ombudsperson to deal with complaints.

Mutations in the gene-encoding SERCA1, the fast-twitch skeletal muscle sarcoplasmic reticulum Ca2+ ATPase, are associated with Brody disease

Brody disease is a rare inherited disorder of skeletal muscle function. Symptoms include exercise-induced impairment of skeletal muscle relaxation, stiffness and cramps. Ca2+ uptake and Ca2+ ATPase activities are reduced in the sarcoplasmic reticulum, leading to the prediction that Brody disease results from defects in the ATP2A1 gene on chromosome 16p12.1-12.2, encoding SERCA1, the fast-twitch skeletal muscle sarcoplasmic reticulum Ca2+ ATPase. A recent search, however, did not reveal any mutations in the ATP2A1 gene in three Brody patients. We have now associated Brody disease with the autosomal recessive inheritance of three ATP2A1 mutations in two families, suggesting that the disease is genetically heterogeneous. One mutation occurs at the splice donor site of intron 3, while the other two mutations lead to premature stop codons, truncating SERCA1, deleting essential functional domains and raising the intriguing question: how have these Brody patients partially compensated for the functional knockout of a gene product believed to be essential for fast-twitch skeletal muscle relaxation?

The clinical spectrum of limb girdle muscular dystrophy. A survey in The Netherlands

A cross-sectional study was performed in the Netherlands to define the clinical characteristics of the various subtypes within the broad and heterogeneous entity of limb girdle muscular dystrophy (LGMD). An attempt was made to include all known cases of LGMD in the Netherlands. Out of the reported 200 patients, 105 who fulfilled strictly defined criteria were included. Forty-nine patients, mostly suffering from dystrophinopathies and facioscapulohumeral muscular dystrophy, appeared to be misdiagnosed. Thirty-four cases were sporadic, 42 patients came from autosomal recessive and 29 from autosomal dominant families. The estimated prevalence of LGMD in the Netherlands was at least 8.1 x 10(-6). The clinical features of the autosomal recessive and sporadic cases were indistinguishable from those of the autosomal dominant patients, although calf hypertrophy was seen more frequently, and the course of the disease was more severe in autosomal recessive and sporadic cases. The pectoralis, iliopsoas and gluteal muscles, hip adductors and hamstrings were the most affected muscles. Distal muscle involvement occurred late in the course of the disease. Facial weakness was a rare phenomenon. The severity of the clinical picture was correlated with a deteriorating lung function. All autosomal dominantly inherited cases showed a mild course, although in two families life-expectancy was reduced because of concomitant cardiac involvement.

A newly recognized autosomal dominant limb girdle muscular dystrophy with cardiac involvement

Sixty-five members of three families with limb girdle muscular dystrophy (LGMD) underwent neurological, cardiological, and ancillary investigations. Thirty-five individuals were diagnosed as having slowly progressive autosomal dominant LGMD. Symmetrical weakness started in the proximal lower limb muscles, and gradually upper limb muscles also became affected. Early contractures of the spine were absent. Contractures of elbows and Achilles tendons were either minimal or late. Serum creatine kinase activity was normal to moderately elevated. Electromyogram and muscle biopsy were consistent with a mild muscular dystrophy. Cardiological abnormalities, found in more than one-half the patients, included dysrhythmias and atrioventricular (AV) conduction disturbances presenting as bradycardia, syncopal attacks necessitating pacemaker implantation, and sudden cardiac death. There was a significant relation between the severity of AV conduction disturbances and age. In nearly all patients, neuromuscular symptomatology preceded cardiological involvement. The early recognition of this previously not described, autosomal dominant LGMD with life-threatening cardiac involvement offers an opportunity for therapeutic intervention.

Riboflavin-responsive complex I deficiency

Three patients from a large consanguineous family, and one unrelated patient had exercise intolerance since early childhood and improved by supplementation with a high dosage of riboflavin. This was confirmed by higher endurance power in exercise testing. Riboflavin had been given because complex I, which contains riboflavin in FMN, one of its prosthetic groups, had a very low activity in muscle. Histochemistry showed an increase of subsarcolemmal mitochondria. The low complex I activity contrasted with an increase of the activities of succinate dehydrogenase, succinate-cytochrome c oxidoreductase and cytochrome c oxidase. Isolated mitochondria from these muscle specimens proved deficient in oxidizing pyruvate plus malate and other NAD(+)-linked substrates, but oxidized succinate and ascorbate at equal or higher levels than controls. Two years later a second biopsy was taken in one of the patients, and the activity of complex I had increased from 16% to 47% of the average activity in controls. In the four biopsies, cytochrome c oxidase activity correlated negatively with age. We suspect that this is due to reactive oxygen species generated by the proliferating mitochondria and peroxidizing unsaturated fatty acids of cardiolipin. Three of the four patients had low blood carnitine, and all were found to have hypocarnitinemic family members.

Differential diagnosis in spinal and bulbar muscular atrophy clinical and molecular aspects

Kennedy disease is caused by an enlarged trinucleotide repeat sequence within the androgen receptor gene. We report here seven male patients with a benign motor neuron syndrome highly analogous to Kennedy disease but with a normal trinucleotide repeat.

Ca2+ homeostasis in Brody's disease. A study in skeletal muscle and cultured muscle cells and the effects of dantrolene an verapamil

Brody's disease, i.e., sarcoplasmic reticulum (SR) Ca(2+)-dependent Mg(2+)-ATPase (Ca(2+)-ATPase) deficiency, is a rare inherited disorder of skeletal muscle function. Pseudo-myotonia is the most important clinical feature. SR Ca(2+)-ATPase and Ca2+ homeostasis are examined in m. quadriceps and/or cultured muscle cells of controls and 10 patients suffering from Brody's disease. In both m. quadriceps and cultured muscle cells of patients, the SR Ca(2+)-ATPase activity is decreased by approximately 50%. However, the concentration of SR Ca(2+)-ATPase and SERCA1 are normal. SERCA1 accounts for 83 and 100% of total SR Ca(2+)-ATPase in m. quadriceps and cultured muscle cells, respectively. This implies a reduction of the molecular activity of SERCA1 in Brody's disease. The cytosolic Ca2+ concentration ([Ca2+]i) at rest and the increase of [Ca2+]i after addition of acetylcholine are the same in cultured muscle cells of controls and patients. The half-life of the maximal response, however, is raised three times in the pathological muscle cells. Addition of dantrolene or verapamil after the maximal response accelerates the restoration of the [Ca2+]i in these muscle cells. The differences in Ca2+ handling disappear by administration of dantrolene or verapamil concomitantly with acetylcholine. The reduced Ca2+ re-uptake from the cytosol presumably due to structural modification(s) of SERCA1 may explain the pseudo-myotonia in Brody's disease. Single cell measurements suggest a beneficial effect of dantrolene or verapamil in treating patients suffering from Brody's disease.

[Course of chronic idiopathic polyneuropathy during middle age and older: 2-year follow-up study]

OBJECTIVE

To study the clinical features and natural course of idiopathic polyneuropathy.

DESIGN

Prognostic and descriptive cohort study.

SETTING

University Hospital, Utrecht, the Netherlands.

METHOD

75 patients (46 men, 29 women) with a mean age of 56.5 years at onset of symptoms were clinically investigated during two years.

RESULTS

The features of chronic idiopathic polyneuropathy were heterogeneous. Clinically, 44 patients had a sensorimotor, 29 patients a sensory and 2 patients a motor polyneuropathy. Electrophysiological and nerve biopsy studies were compatible with an axonal polyneuropathy. The overall clinical course was slowly progressive. None of the patients became severely disabled. After one year of follow up one patient proved to have a hereditary neuropathy. In the other 74 patients no cause for the polyneuropathy was found even after 2 years of follow-up.

CONCLUSION

Chronic idiopathic polyneuropathy is a heterogeneous entity, leading to only slight disability. The neuropathy is due to axonal degeneration.

Daytime sleep in myotonic dystrophy is not caused by sleep apnoea

Daytime sleepiness is common in myotonic dystrophy and might be attributed to disturbed nocturnal breathing. Seventeen out of 22 patients complained of excessive daytime sleepiness, resembling "idiopathic hypersomnolence". Sleep apnoea might have contributed to daytime sleepiness in only three of 17 patients. Treatment with the central stimulant methylphenidate produced sustained benefit in seven out of 11 patients tested. Daytime sleepiness in myotonic dystrophy is usually caused by dysfunction of central sleep regulation and not by disturbed nocturnal breathing.

Vitamin-responsive complex I deficiency in a myopathic patient with increased activity of the terminal respiratory chain and lactic acidosis

An 11-year-old girl with exercise intolerance, fatiguability from early childhood, had high blood lactate levels. Histochemistry showed increased activity of succinate dehydrogenase at the periphery of the muscle fibres, whereas aggregates of mitochondria were seen by electron microscopy. Biochemical investigation of isolated mitochondria and homogenate from muscle showed evidence of a severe complex I deficiency. In contrast, succinate dehydrogenase, complex II+III and complex IV were increased in activity. Therapy with biotin, riboflavin, nicotinamide, carnitine and amino acids resulted in an improvement of her endurance. 31P NMR spectroscopy of her forearm muscle showed a decreased ratio of phosphocreatine (PCr) over ATP. After exercise the PCr recovery rate was 26% of the average rate in 20 healthy untrained controls. When the therapy was suspended the PCr/ATP ratio at rest decreased from 2.60 to 2.34, and the PCr recovery rate after exercise decreased to 21% of the average control rate. The therapy was reinstituted but only riboflavin and carnitine were given. The PCr/ATP ratio increased to 2.60 and the PCr recovery rate increased to 32% of the control rate. Improvement of the energy metabolism in patients with defects in the oxidative phosphorylation may add to the quality of life; 31P NMR spectroscopy can measure these improvements.

[Intravenously-administered immunoglobulins as first-choice agent in juvenile dermatomyositis]

Dermatomyositis is an acquired disease characterised by symmetric predominantly proximal muscle weakness of the arms and legs, and misery. It may be associated with myalgia and there is often a characteristic rash. The mainstay of therapy is corticosteroids. Recently efficacy of intravenous immunoglobulin (IVIg) in chronic refractory dermatomyositis was reported. Because corticosteroids can cause serious side effects, we treated a seven-year-old girl suffering from dermatomyositis with IVIg as initial therapy. After two courses of IVIg infusions at a dose of 0.4 g/kg/day for five consecutive days, the patient made a rapid and complete recovery. This case shows that IVIg may be effective as initial therapy in patients with dermatomyositis. Whether IVIg is really a better treatment than corticosteroids should be investigated in a randomised study.

Synthesis and in situ localization of lysosomal alpha-glucosidase in muscle of an unusual variant of glycogen storage disease type II

The lysosomal alpha-glucosidase activity is reduced to 10% to 25% of the average control value in most late-onset cases of glycogen storage disease type II (GSDII). Some adult patients, however, have been identified with an exceptionally low (< 5%) residual enzyme activity. We have investigated one such unusual variant. The rate of alpha-glucosidase synthesis appeared normal but the residual enzyme activity was only approximately 3% in cultured fibroblasts, cultured muscle cells, and muscle tissue of the patient. It appeared that fully matured enzyme molecules were more abundantly present in muscle tissue than in cultured cells. The acid phosphatase activity of affected muscle fibers was enhanced due to an increased number of lysosomes. Lysosomes were particularly abundant in vacuolated areas and they contained, as judged by immunoelectron microscopy, even more alpha-glucosidase molecules than usual. An excessive amount of enzyme molecules were also observed in the endoplasmic reticulum, the site of lysosomal enzyme synthesis, and the cisternae were dilated. These observations suggest that the lysosomal system is stimulated in response to intralysosomal glycogen storage and onset of cellular injury. We hypothesize that the onset of gross pathologic abnormalities is delayed in this particular case of adult GSDII by an increased synthesis of lysosomal alpha-glucosidase, and as a consequence, an increased residual activity in storage-prone muscle fibers.

Problems with the biochemical diagnosis in mitochondrial (encephalo-)myopathies

Patients suffering from a mitochondrial (encephalo-)myopathy have a remarkable clinical heterogeneity. A reliable and extensive investigation must be performed in order to obtain a correct diagnosis, but many factors may influence the ultimate results of these investigations leading, under certain circumstances, to an incorrect diagnosis. Patients selection is of crucial importance. Metabolic examination of body fluids, particularly with respect to lactate accumulation, is used as a selection criterion for further examinations. Numerous aspects associated with this metabolic examination have been critically evaluated, including the phenomenon of other causes of lactic acidaemia apart from mitochondrial disorders. Correct performance of in vivo function tests may contribute to a reduction of the number of missed diagnoses. Selection of the controls for biochemical investigations must be accurately be performed to obtain reliable reference values. Knowledge of the age-dependency of the biochemical parameters is necessary for a correct interpretation. It goes without saying that the choice of the tissue for biochemical investigations is of utmost importance. Knowledge of the tissue-specific occurrence of some defects in the mitochondrial respiratory chain is necessary. The biochemical examinations can be performed both in biopsy and autopsy material but only under certain conditions. Diagnostic approach requires application of reliable biochemical methods which are described. One of the most intriguing aspects in the diagnosis of mitochondrial disorders is the significance of a defect in relation to the residual enzyme activity found in the patient. Moreover, attention is paid to relevant items such as the occurrence of multiple and secondary defects.(ABSTRACT TRUNCATED AT 250 WORDS)

[Application of combined DNA and dystrophin protein analysis in the diagnosis of Duchenne's and Becker's muscular dystrophy in 102 Dutch patients]

The recent progress in molecular genetic studies on Duchenne and Becker muscular dystrophy (DMD, BMD) had an important spin-off for our diagnostic abilities of both muscle disease. The mapping and isolation of the DMD gene which codes for the 427 kD cytoskeletal protein dystrophin made it possible to diagnose 80-85% of the patients by means of DNA analysis. At present, most of the remaining 15-20% of the patients can be diagnosed by protein analysis. In this report we describe the analysis of dystrophin in a group of 102 Dutch patients with muscular dystrophies. An immunohistochemical and immunobiochemical study of dystrophin was performed on muscle tissue, partly integrated with DNA analysis. In this study we underline the value of dystrophin analysis in all patients suspected of DMD, BMD or other muscular dystrophies, particularly in those without detectable DNA mutations. By means of integrated DNA/dystrophin analysis 98% of the DMD patients and 90% of th BMD patients and their families can now be provided with an unambiguous diagnosis. In particular, discrimination between BMD and other muscular dystrophies has strongly improved.

Intravenous immunoglobulin treatment in patients with chronic inflammatory demyelinating polyneuropathy: a double blind, placebo controlled study

Patients with a clinical diagnosis of chronic inflammatory demyelinating polyneuropathy (CIDP) were randomised in a double-blind, placebo-controlled multicentre trial to investigate whether high-dose intravenous immunoglobulin treatment (IVIg) for 5 consecutive days has a beneficial effect. Fifteen patients were randomised to IVIg and 13 to placebo. In the IVIg treatment group 4 patients improved and 3 patients in the placebo group. The degree of improvement of the patients in the IVIg treatment group was no different from the patients in the placebo group. Electrophysiological studies did not show significant differences between the groups. Since a previously performed cross-over trial showed that a selected group of CIDP patients responded better to IVIg than to placebo, it is concluded that we need better criteria to select CIDP patients for treatment with IVIg.

Birth and population prevalence of Duchenne muscular dystrophy in The Netherlands

Mutations causing Duchenne muscular dystrophy (DMD) have a short survival. Therefore, birth and population prevalence are maintained by new mutations. The present inventory was made to estimate the birth and population prevalence rates of DMD in the Netherlands. Seven methods of case identification were used. Data on 496 definite, probable or possible DMD patients born since 1961, or alive on January 1, 1983, were obtained. Several methods gave an estimated ascertainment of more than 95%. The prevalence rate at birth of DMD was estimated at 23.7 x 10(-5) (1:4215) male live births (MLB) yearly. The prevalence rate in the male population on January 1, 1983 was 5.4 x 10(-5) (1:18496). About 1% of the males in this study may have autosomal recessive Duchenne-like muscular dystrophy. Until now there has been no convincing evidence for geographic differences in DMD prevalence at birth. A list of frequency studies of Duchenne muscular dystrophy is included. The DMD mutation rate calculated by the indirect method is 7.9 x 10(-5) genes per generation. However, this may well be an over-estimate, as this method does not account for germline mosaicism. Using a modified sex ratio method the proportion of sporadic DMD among all cases was estimated to be 0.106 (range 0-0.332). High frequency of germline mosaicism in DMD is a likely cause for the apparent lack of sporadic cases as found in previous studies, if mutation rates in male and female gametes are equal. Therefore, methods for estimating the proportion of new mutants in DMD should take germline mosaicism into account. The modified sex ratio method allows incorporation of data on germline mosaicism if available.

Intravenous immunoglobulin treatment in patients with chronic inflammatory demyelinating polyneuropathy. Clinical and laboratory characteristics associated with improvement

Of 52 patients fulfilling the criteria of chronic inflammatory demyelinating polyneuropathy, 20 (38%) did not improve after intravenous immunoglobulin treatment, two (4%) had a short-lasting improvement and subsequent infusions had no effect, nine (17%) reached a spontaneously or therapeutically induced complete remission, and 21 patients (40%) needed intermittent infusions to maintain improvement. All patients who improved initially had symptoms that significantly interfered with life-style. After treatment, 90% of these patients were independent in their daily activities. Significantly associated with improvement were disease duration of less than 1 year, progression of weakness until treatment, absence of discrepancy in weakness between arms and legs, areflexia of the arms, and slowed nerve conduction velocity of the motor median nerve. The probability of improvement if all these features are present in 93%.

Congenital demyelinating motor and sensory neuropathy with focally folded myelin sheaths

Six patients (5 index cases and 1 sib) with a congenital motor and sensory neuropathy are described. The clinical, genetic and electrophysiological features resembled Dejerine-Sottas disease or hereditary motor and sensory neuropathy (HMSN) type III. Sural nerve biopsy of 5 patients revealed segmental demyelination and remyelination with hypertrophic changes, although onion bulbs were not as ubiquitous as in classical HMSN type III. A striking discriminating feature from HMSN type III was an abundance of focal myelin thickenings (tomacula) present in nearly all teased fibres. Possible pathogenic implications are discussed. These cases corroborate the heterogeneity of congenital motor and sensory neuropathies.

Oxidative phosphorylation in human muscle in patients with ocular myopathy and after general anaesthesia

The fuel preference of human muscle mitochondria has been given. Substrates which are oxidized with low velocity cannot be used to detect defects in oxidative phosphorylation. After general anaesthesia, the oxygen uptake with the different substrates is much lower than after local analgesia. The latter was therefore used in the subsequent study. In 15 out of 18 patients with ocular myopathy, defects in oxidative phosphorylation could be detected in isolated muscle mitochondria prepared from freshly biopsied tissue. Measurement of the activity of segments of the respiratory chain in homogenate from frozen muscle showed no, or minor defects. In two of these patients showing exercise intolerance, decreased oxidation of NAD(+)-linked substrates and apparently normal mitochondrial DNA, further study revealed deficiency of pyruvate dehydrogenase in a girl with ptosis and a high Km of complex I for NADH in a man. Both patients responded to vitamin therapy.

Non-familial degenerative disease and atrophy of brainstem and cerebellum. Clinical and CT data in 47 patients

We studied the clinical features of 47 patients with a non-hereditary degenerative disease and with atrophy of brainstem or cerebellum or both in CT scanning. There was no relation between the CT findings and duration or severity of the disease, nor with the kind of the neurological signs which comprised ataxia, a hypokinetic rigid syndrome, oculomotor abnormalities, upper and lower motor neuron signs, orthostatic hypotension and dementia. The 2 main diagnoses were olivopontocerebellar atrophy (OPCA), or a combination of OPCA and striatonigral degeneration (SND). The differential diagnosis with Parkinson's disease and progressive supranuclear palsy was discussed. We concluded, that a CT scan is warranted in all cases of suspected Parkinson's disease, especially in those without tremor, and in cases of motoneuron disease with broad-based gait. In our patients with mainly hypokinesia and rigidity, levodopa treatment had no or brief beneficial effects. If ataxia predominated, OPCA appeared the most sensible diagnosis; if a hypokinetic-rigid syndrome predominated, the diagnoses SND plus OPCA appeared the most suitable. We assessed the degree of atrophy on CT subjectively, because an interobserver study of 60 normal CT scans, did not produce reliable measurements.

Chronic inflammatory demyelinating polyneuropathy. Conduction failure before and during immunoglobulin or plasma therapy

An earlier study has shown that patients with chronic inflammatory demyelinating polyneuropathy may improve after the infusion of fresh frozen plasma or high dose intravenous immunoglobulin. We studied 8 such responding patients with neurophysiological techniques. Before treatment all patients had decreased compound muscle action potentials (CMAP) and slowing of conduction. During several courses of treatment a progressive increase of the CMAPs occurred and in 5 patients a correlation between the CMAPs of the abductor pollicis brevis muscle and grasp force could be demonstrated. In 2 patients, increase in strength was correlated with shortening of the distal motor latency; no significant relationships were found between strength and conduction velocity. Different patterns in the distribution of conduction failure were observed. In 2 patients, lesions were distributed along the length of the motor fibres, whereas the sensory system was spared. In another 2 patients the lesions, most likely demyelinating, were localized distally and included the sensory system. The 4 remaining patients were more difficult to classify, but individually showed greater resemblance to one or other of the two described patterns. Different patterns of conduction failure may reflect different pathogenetic mechanisms.

Anticipation in myotonic dystrophy: fact or fiction?

In 1918 Fleischer reported that after transmission from one generation to the next, myotonic dystrophy has an earlier onset and is more severe. The hypothesis put forward by Penrose in 1948 that 'anticipation' is caused by bias of index case selection was based on theoretical arguments only and has not been supported by clinical observations. This hypothesis was tested in a clinical and genetic study of 14 families with myotonic dystrophy. Excluding index patients, an earlier onset in the child was found in 98% of 61 parent-child pairs. A greater mean difference in age of onset was found with transmission via the father than via the mother. The comparison of the severity of the disease between parents and children was difficult because of the variation in symptoms but, in general, the disease was more severe in the child than in the parent. The penetrance of the abnormal gene was nearly complete in the 14 families combined, leaving little room for the observation of 'complementary' parent-child pairs in the future. Also in retrospect no complementary parent-child pairs were found in the first generations. Fertility was severely reduced only in the very early onset patient group and this selective infertility cannot be responsible for the total amount of anticipation observed. It is therefore concluded that anticipation may be inherent in the transmission of myotonic dystrophy. This has important consequences for genetic counselling.

Congenital paucity of secondary synaptic clefts (CPSC) syndrome in 2 adult sibs

We studied 2 elderly sibs with a congenital form of myasthenia who had ptosis since early childhood. The extraocular muscles were weak and the proximal limb muscles became slowly weaker throughout life. Laboratory investigations of biopsies of intercostal muscle from these patients showed the following abnormalities: the amplitude of miniature end-plate potentials was small and the binding of 125I-alpha-bungarotoxin at the end-plate area was reduced, suggesting a considerable reduction of acetylcholine receptors (AChRs). Secondary synaptic clefts were scarce, whereas the number of end-plates per muscle fiber was increased. There was no indication of impaired transmitter release as the quantal content was within the range of controls. We conclude that these patients suffered from the congenital paucity of secondary synaptic clefts (CPSC) syndrome, described recently in 2 cases of myasthenic children, and suggest that the CPSC syndrome is a developmental disorder in which a deficiency of AChRs may be caused by a decreased clustering or insertion of AChRs. The increased number of end-plates per muscle fiber in both patients could serve as a compensatory mechanism.

Carnitine deficiency, mitochondrial dysfunction and the heart. Identical defect of oxidative phosphorylation in muscle mitochondria in cardiomyopathy due to carnitine loss and in Duchenne muscular dystrophy

Cardiomyopathies are often caused by a metabolic defect. Carnitine deficiency and mitochondrial defects in the metabolism of acyl-CoA, including defects in oxidative phosphorylation, start the same circular mechanism of mitochondrial doom. Patients with cardiomyopathy due to carnitine loss are cured by carnitine supplementation. In such a patient we found defective oxidative phosphorylation in isolated muscle mitochondria. The stimulation of the respiratory rate with all substrates by ADP was decreased, probably the cause of inhibition of the adenine nucleotide translocator by accumulating long-chain acyl-CoA. The same condition was encountered in patients with Duchenne muscular dystrophy, who often get cardiomyopathy in the course of the disease process.

Prospect for enzyme therapy in glycogenosis II variants: a study on cultured muscle cells

Impairment of skeletal muscle function is the common feature of distinct clinical forms of glycogenosis type II. In the present study, muscle cultures from different patients were used to investigate the cause of clinical heterogeneity and the feasibility of enzyme replacement therapy. The activity of acid alpha-glucosidase appears to be the primary factor in determining the extent of lysosomal glycogen storage in muscle, and thereby the clinical severity of the disease. Neutral alpha-glucosidases do not seem influential. Correction of the enzymatic defect was achieved in skeletal muscle cultures from patients by administration of a "high-uptake" form of acid alpha-glucosidase, purified from human urine. The enzyme reaches the lysosomes, including the glycogen storage vacuoles, and the lysosomal glycogen content is reduced to control level. In normal muscle cells 20% of the total cellular glycogen pool is segregated in lysosomal compartments. This percentage is higher than in fibroblasts, which may partly explain why muscles are more prone to store glycogen. The relevance of this study for enzyme therapy is discussed.

Exercise responses in patients with an enzyme deficiency in the mitochondrial respiratory chain

Responses to exercise were obtained in six patients with a biochemically diagnosed enzyme deficiency at the level of NADH-CoQ reductase. The responses were compared with those of a control group, consisting of fourteen patients with inexplicable dyspnoea or muscle pain during exercise, for which no firm diagnosis could be established and of which the exercise responses were in the normal range. Metabolic, ventilatory and cardiological variables such as oxygen uptake (VO2), minute ventilation (VE), respiratory exchange ratio (R), heart rate (HR) and difference in blood lactate or base-excess (BE) between rest and maximal workload were measured during cycle ergometry from samples obtained in the last minutes of four minute periods, in which the load increased stepwise by 30 W per four minutes. The threshold of lactate metabolism (Tlact) was assumed to be equal to the threshold determined both by the VO2 at which the VE versus VO2 response started to deviate from a straight line and the ventilatory equivalent for oxygen (VE/VO2) showed a minimum (Tvent), Tvent was estimated from the mean of these values, obtained by linear and parabolic regression analysis respectively. In the patient group, mean values for symptom limited maximal VO2 (VO2,max,sl; % of VO2,max,ref), Tvent (% of VO2,max,ref) and R at maximal workload were 43, 17 and 1.23 against 85, 47 and 1.06 for the same variables in the control group, respectively. The differences were highly significant (p less than 0.001; p less than 0.005 for mean R difference). Mean maximal HR and mean change in blood lactate or BE were not significantly different in the two groups.(ABSTRACT TRUNCATED AT 250 WORDS)

Exercise responses in patients with an enzyme deficiency in the mitochondrial respiratory chain

Responses to exercise were obtained in six patients with a biochemically diagnosed enzyme deficiency at the level of NADH-CoQ reductase. The responses were compared with those of a control group, consisting of fourteen patients with inexplicable dyspnoea or muscle pain during exercise, for which no firm diagnosis could be established and of which the exercise responses were in the normal range. Metabolic, ventilatory and cardiological variables such as oxygen uptake (VO2), minute ventilation (VE), respiratory exchange ratio (R), heart rate (HR) and difference in blood lactate or base-excess (BE) between rest and maximal workload were measured during cycle ergometry from samples obtained in the last minutes of four minute periods, in which the load increased stepwise by 30 W per four minutes. The threshold of lactate metabolism (Tlact) was assumed to be equal to the threshold determined both by the VO2 at which the VE versus VO2 response started to deviate from a straight line and the ventilatory equivalent for oxygen (VE/VO2) showed a minimum (Tvent), Tvent was estimated from the mean of these values, obtained by linear and parabolic regression analysis respectively. In the patient group, mean values for symptom limited maximal VO2 (VO2,max,sl; % of VO2,max,ref), Tvent (% of VO2,max,ref) and R at maximal workload were 43, 17 and 1.23 against 85, 47 and 1.06 for the same variables in the control group, respectively. The differences were highly significant (p less than 0.001; p less than 0.005 for mean R difference). Mean maximal HR and mean change in blood lactate or BE were not significantly different in the two groups.(ABSTRACT TRUNCATED AT 250 WORDS)

Defects in oxidative phosphorylation. Biochemical investigations in skeletal muscle and expression of the lesion in other cells

Mitochondria are very vulnerable to genetic and environmental damage. If a patient is suspected of having a mitochondrial disease, elevated blood lactate, lowered blood free carnitine, abnormal urinary organic acids and carnitine esters and tissue histopathology may help with the diagnosis. For biochemical assessment of the defect, muscle is the tissue of choice even when involvement of other organs like heart or brain is more prominent. We have studied isolated muscle mitochondria and homogenates from muscle biopsies in 250 patients, and have detected in more than one third mitochondrial defects in oxidative phosphorylation, dehydrogenases, non-redox enzymes catalyzing synthesis of fuel molecules and in the carnitine system. Several patients showed more than one defect. We have selected eight patients to illustrate how a relatively simple series of investigations in both isolated mitochondria and homogenate can be used for the identification of defects in oxidative phosphorylation in a small amount of muscle (200 mg or more). Identification of the defect(s) is important since it may provide the basis for rational treatment. A minority of the patients recovered partly or completely, which is unique in treatment of inborn errors of subcellular organelles. An important aspect of mitochondrial dysfunction is the tissue specificity. The defect may be systemic but is often clinically expressed in only one or a few tissues. Rarely, tissue-specific defects can be understood on the basis of tissue-specificity of mitochondrial (iso-)enzymes. Mitochondrial deficiencies of all biotin enzymes and most CoA-linked enzymes are expressed in fibroblasts; most respiratory chain defects are not. When mitochondrial ATP synthesis has been compromised by a mitochondrial defect, secondary lesions may be generated by changes in mitochondrial protein synthesis, activated proteases and phospholipases, increased matrix CoA and resulting carnitine deficiency, decrease in Krebs cycle intermediates and increased free radical formation and lipid peroxidation.

Myopathy with abnormal mitochondria, transient low electron transport capacity in the respiratory chain, and absence of energy transduction at sites 1 and 2 in vitro

A male adult with exercise-related myalgia and weakness from the age of 17 years, developed contractions after moderate exertion which were electrically silent. Triglyceride loading or prolonged fasting provoked excessive ketosis. His isolated muscle mitochondria had severe blockade of the respiratory chain, particularly of NADH-CoQ reductase. After 1.5 years a second biopsy was performed. The electron transport capacity of the respiratory chain was much improved, but now a lesion was observed in energy transduction of sites 1 and 2 of the respiratory chain. The unexpected abolishment of respiratory chain blockade was paralleled by only mild clinical improvement.

Pleocore disease. Multi-minicore disease and focal loss of cross striations

We report clinical and morphological data on seven patients with a congenital myopathy as well as data concerning five parents. Classical myopathies such as rod disease, centronuclear myopathy or central core disease could be ruled out. Structural abnormalities of intracellular organelles or particulate inclusions were rare and insignificant. The most prominent and constant features were minicores and focal loss of cross striations, associated with a prevalence of type 1 fibres, increasing with the age at time of biopsy. A carrier state could not be defined in the five examined parents neither on clinical nor on morphological grounds. Although our group of patients could not clinically be distinguished from other congenital myopathies, the combination of the lesions allow their individualization as a subgroup of multicore or minicore disease under the already proposed denomination of pleocore disease [Martin and Busch, abstract in Zentralbl Allg Pathol 124:156 (1980)].

Plasma and gamma-globulin infusion in chronic inflammatory polyneuropathy

We treated 17 patients with chronic inflammatory polyneuropathy (CIP) with infusions of fresh-frozen plasma (FFP). Thirteen patients had a beneficial response: 12 improved considerably and one moderately. The first signs of improvement were seen within 8 days of the onset of treatment. None of these patients had had spontaneous remissions for 2 months prior to treatment, and none had received immunosuppressive medication during the plasma infusions. The treatment effect was short-lasting in 9 patients. Re-institution of the FFP infusions was always followed by improvement. The same effect could be achieved by intravenous gamma-globulin. We conclude that infusions with FFP, of which the IgG fraction is the effective part, may induce a rapid and clinically important improvement in patients with CIP.

Uptake and stability of human and bovine acid alpha-glucosidase in cultured fibroblasts and skeletal muscle cells from glycogenosis type II patients

Acid alpha-glucosidase (EC 3.2.1.20) was purified from human placenta and bovine testis by affinity chromatography using concanavalin A (conA) and Sephadex G 200. When added to the culture medium of human fibroblasts, the enzyme purified from bovine testis is taken up with a 200-fold higher efficiency than the enzyme from human placenta. Uptake of acid alpha-glucosidase from bovine testis is mediated by the mannose-6-phosphate receptor, whereas only a minor fraction of placental enzyme appears to be equipped with the mannose-6-phosphate recognition marker. Once internalized, both human and bovine acid alpha-glucosidase demonstrate a half-life of about 10 days in fibroblasts from control individuals and patients with different clinical forms of glycogenosis type II (Pompe's disease, acid alpha-glucosidase deficiency). Evidence is presented that the mannose-6-phosphate receptor is also present on the plasma membrane of the clonal myogenic skeletal muscle cell lines G8-1 and L6J1 (respectively from mouse and rat origin) and on cultured human skeletal muscle cells derived from a muscle biopsy. Addition of bovine testis acid alpha-glucosidase to skeletal muscle cell cultures from an adult patient with glycogenosis type II leads to complete correction of the enzyme deficiency.

Hereditary neuralgic amyotrophy. Clinical, genetic, electrophysiological and histopathological studies

Clinical, genetic, electrophysiological and histopathological studies in a four-generation family with hereditary neuralgic amyotrophy (HNA) are described. Clinically two kinds of attack could be distinguished: (1) the classical type with pain and weakness lasting for weeks to months, leaving atrophy and sometimes residual weakness; 2) attacks consisting of recurrent pain and weakness lasting for a few days and occurring about once a week for several months, also resulting in persisting atrophy and weakness. Genetically a strong association was found between HNA and hypotelorism, probably due to pleiotropism of one single gene. Close linkage with any of 29 genetic markers was not present. The electrophysiological findings indicated that a local process in the brachial plexus, possibly demyelination or a conduction block, was the primary pathophysiological mechanism. Nevertheless, the sural nerve of the index case, biopsied 5 months after the onset of an attack, showed a decreased number of myelinated nerve fibres per cross-sectional area. Apparently, other parts of the peripheral nervous system may be affected subclinically in an attack of brachial plexopathy. The central and peripheral nervous system of his mother, 30 years after her last attack of HNA, showed only nonspecific changes. Tomacula were not seen in either case. HNA and hereditary liability to pressure palsies (HLPP) are distinctly different disorders.