Urinary titin as a biomarker in Fukuyama congenital muscular dystrophy

Fukuyama congenital muscular dystrophy (FCMD) is the second most prevalent childhood-onset muscular dystrophy in Japan. It is an autosomal recessive disorder caused by the fukutin mutation (FKTN), characterized by muscle wasting and brain abnormalities. So far, serum creatine kinase (CK) is recognized as the only biomarker for FCMD. Recently, an ELISA assay to quantify the N-terminal fragment of titin in urine was developed. Urinary titin concentration is elevated in patients with Duchenne muscular dystrophy (DMD) compared to normal controls. Levels vary according to age with excellent sensitivity and specificity for detecting DMD, and they can be used as a diagnostic and disease progression marker. In this study, we measured the urinary titin concentration of 18 patients with FCMD. It was remarkably higher than normal controls and correlated with CK. Especially in homozygotes, the score for gross motor function measure, which is a quantitative motor scale for FCMD, was correlated with urinary titin concentration. Elevated urinary titin concentrations were thought to be reflective of a common pathophysiology with DMD. Urinary titin concentrations can assist with making the diagnosis of FCMD and to estimate the patient's motor function at that point.     

Two Dutch siblings with congenital muscular dystrophy (Fukuyama type)

Two Dutch siblings are described suffering from muscular weakness, hypotonia, severe joint contractures, mental retardation and epileptic fits. E.M.G. showed a characteristic myopathic pattern. Muscle biopsy revealed changes consistent with congenital muscular dystrophy. On CT marked hypodensities of the cerebral white matter were noticed. These findings are consistent with congenital muscular dystrophy of the Fukuyama type, a peculiar form of congenital muscular dystrophy, extremely rare outside Japan.     

Immunochemical study of connectin (titin) in neuromuscular diseases using a monoclonal antibody: connectin is degraded extensively in Duchenne muscular dystrophy

Connectin (also called titin) is a myofibrillar elastic filament which links a thick filament to a neighbouring Z line in a sarcomere and thus contributes significantly to the elastic property of myofibrils. In the present study, the degradation state of connectin in biopsied skeletal muscles from various neuromuscular diseases was investigated by Western blot analysis using a monoclonal antibody which reacts extensively with the degradation products of connectin. In Duchenne muscular dystrophy (DMD), connectin was degraded progressively and relentlessly after 5 years of age. In Becker muscular dystrophy, degradation of connectin was much less than in DMD. Connectin was well preserved in normal controls, and was only minimally degraded in Charcot-Marie-Tooth disease, amyotrophic lateral sclerosis, limb girdle muscular dystrophy and myotonic dystrophy, even when the biopsied muscles showed a similar degree of weakness as those of DMD. The degradation of connectin, even though secondary, is presumed to play an important role in the pathogenesis of myofibrillar degeneration in DMD.     

Vascular alterations in Fukuyama type congenital muscular dystrophy

Blood vessels in muscle biopsy specimens from 6 Fukuyama type congenital muscular dystrophy (FCMD) patients were examined by electron microscopy and compared with ones in non-diagnostic biopsy specimens from age-matched controls and patients with childhood neuromuscular disorders. The most striking feature was the blister-like swelling of vascular endothelial cells in the biopsied muscle specimens from 5 of the 6 patients with FCMD. Morphometric analysis of capillaries in biopsied muscles showed the extremely greater capillary, endothelial and pericyte areas in the FCMD patients than in controls. These phenomena are quite similar to those found in Duchenne muscular dystrophy (DMD) at the preclinical stage and suggest an as yet undetermined process in blood vessels in FCMD as well as DMD. An immunohistochemical study involving dystrophin antibodies showed positive staining in FCMD.     

Ocular findings in Fukuyama type congenital muscular dystrophy

In Fukuyama type congenital muscular dystrophy (FCMD), congenital muscular dystrophy and anomalies of the central nervous system are regarded as the major features, but the existence of ocular lesions has hardly been recognized as being important. In the present study, close ophthalmologic examinations were performed on 11 patients with FCMD, and we found myopia, weakness of the orbicularis oculi, congenital nystagmus, cortical blindness, optic atrophy, chorioretinal degeneration, etc. In particular, the chorioretinal degeneration observed in the ocular fundus was considered to be specific to FCMD. It is thought that these ocular lesions or changes are caused by the same mechanism as that involved in the central nervous system anomalies.     

A genetic study of the Fukuyama type congenital muscular dystrophy

A genetic study was carried out on 153 families with 186 Fukuyama type congenital progressive muscular dystrophy (FCMD) patients. Consanguineous marriage of parents was found in 41 families (26.80%). Inbreeding coefficients in the patients was 10 times as high as that of the general population. Both sexes were almost equally affected (M:F = 1.1:1.0). No single parent of the patients was affected. Recurrence among siblings was frequent (9 out of 41 siblings in offspring of related parents and 18 out of 110 siblings in offspring of unrelated parents were affected. The segregation ratio was 23.91-27.08% in offspring of related parents, 20.00-22.94% in offspring of unrelated parents, these values being not significantly different from the 25% expected from the assumption of autosomal recessive mode of inheritance. In the sample two twin pairs were included, of which one male isosexual pair was concordant. Sporadic cases were not significantly more numerous than expected. All these data indicate that the disorder is caused by homozygosity of an autosomal recessive gene. Frequency of the gene was estimated to be 5.2-9.7 X 10(-3) and frequency of the patients 6.9-11.9 X 10(-5). Mutation rate was estimated to be 6.9-11.9 X 10(-5).     

Morphological study of the brainstem in Fukuyama type congenital muscular dystrophy

We have observed sudden clinical death due to Fukuyama-type congenital muscular dystrophy (FCMD). In FCMD, brain abnormalities, such as polymicrogyria, leptomeningeal neuroglial heterotopia and abnormal course of the corticospinal tracts, are well known. We investigated the brainstem of 10 FCMD and 7 control cases. Among the control cases, 5 with Duchenne type muscular dystrophy died of heart failure and 2 died accidental death. In the brainstem, the catecholaminergic neurons characterized by reaction with antiserum to tyrosin hydroxylase showed notable reduction in the reticular formation, vagal nuclei, and nucleus tractus solitarius. Delays or aberrations of neural control may contribute to the pathogenesis of sudden infant death syndrome, and medullary gliosis occurs in the reticular formation of sudden infant death syndrome. The pathogenesis of neurons in the brainstem in FCMD may be similar to that in sudden infant death syndrome. These findings suggest neuronal dysfunction in the brainstem and may be related to respiratory, circulatory, or sleep-wake regulation disorders.     

Diaphragm muscle pathology in Fukuyama type congenital muscular dystrophy

The diaphragm muscle pathology in four patients with Fukuyama type congenital progressive muscular dystrophy (FCMD) was reported. In the diaphragm muscle fibers of three patients aged more than 14 years exhibiting chronic respiratory failure, a lot of electron dense lesions, which varied in size but did not extend over the whole length of the muscle fibers, and a marked increase in mitochondria were observed as well as the dystrophic changes. The dense lesions, consisting of electron dense fibrillary material comparable to Z-band materials in electron density, seemed to be due to Z-band disruption leading to streaming and/or large aggregations of Z-band materials. No mitochondria or other microorganelles were found in these dense lesions. These findings are thought not to be specific to FCMD, but seem to reflect diaphragm muscle fatigue, because, there were no such lesions in the diaphragm muscle of a 2-year-old infant not exhibiting chronic respiratory failure or in muscle at other sites in all patients.     

Fukuyama type congenital muscular dystrophy in a Turkish child

Congenital muscular dystrophy (CMD) is a heterogeneous group of disorders which is associated with more or less degrees of cerebral involvement. There are four separate entities within CMD nosology. Among these Fukuyama's CMD (FCMD) is highly prevalent in Japan, whereas the classic form with normal or subnormal intelligence, also known as the occidental type, covers the vast majority of cases in the West. We report a case of FCMD seen in a Turkish child.     

Clinicopathological study on eyes from cases of Fukuyama type congenital muscular dystrophy

Fukuyama type congenital muscular dystrophy (FCMD) is an autosomal recessive disorder characterized by progressive muscular dystrophy and dysgenesis of the central nervous system and eyes. To clarify the pathomechanism of the ocular involvement in FCMD, we performed postmortem pathological analyses of eyes from three postnatal FCMD cases, two fetal FCMD cases, and three control cases by macroscopic, histopathological, immunohistochemical and in situ hybridization approaches. The macroscopic and histopathological examinations revealed a variety of ocular abnormalities such as folding, fusion or dysplasia of the retinas in the FCMD cases both with and without ophthalmological alterations. Immunoreactivities for collagen IV and laminin, produced by Müller cells, as the basement membrane components, were less intense in the inner limiting membrane of the FCMD retinas than in that of the control retinas. A number of the perivascular glial cells containing S-100 protein and glial fibrillary acidic protein were increased in the postnatal FCMD cases. Immunoreactivities for vimentin, glutamate transporter-1, glutamine synthase and ornithine aminotransferase, expressed in the Müller cells, were undetectable in the fetal FCMD retinas, and reduced in the postnatal FCMD retinas compared with the control retinas. Fukutin mRNA signals were distributed diffusely in the retinoblast layer of the control retinas, focally in the retinoblast layer of the fetal FCMD retinas, and only in the dysplastic areas with rosette formation of the postnatal FCMD retinas, composed of retinoblasts and other retinal cells including the Müller cells. The present findings suggest that the Müller cells are implicated in the retinal pathology of FCMD.     

Survey of Fukuyama type congenital muscular dystrophy in Tokyo]

On the 1st of April in 1988, we identified 26 children with Fukuyama type congenital muscular dystrophy (FCMD) among 1,227,000 children in Tokyo whose ages ranged from 6 to 14 years. The prevalence rate of FCMD was 2.1 per 100,000. All affected children attended special school for crippled children. Mean absence from school on account of illness was 33.9 days in a year. Fifteen among 26 affected children had ability of verbal communication. The loss of gross motor function started at ages 6-7 years but muscle weakness might have occurred earlier. Ten affected children were treated with antiepileptic drugs. Six affected children needed to be hospitalized for the treatment of vomiting with dehydration, acute bronchitis, or pertussis infection during one year until the 1st of April in 1989. Two cases among 26 with FCMD died of respiratory complications shortly after admission.     

Immature astrocytes in Fukuyama congenital muscular dystrophy: an immunohistochemical study

Recent studies of Fukuyama congenital muscular dystrophy have focused on abnormalities of the basement membrane in muscle and brain. The cerebral cortex has a unique basement membrane at the glia limitans, which is intimately related to astrocytes in the developing brain, and the basement membrane may be partially produced by the astrocyte. In this study the cerebral astrocytes in six patients with Fukuyama congenital muscular dystrophy, including two fetal patients, were characterized by immunohistochemical study. In fetal Fukuyama congenital muscular dystrophy, astrocytes reacted less to antibodies of glial fibrillary acidic protein, S-100 protein, and alphaB-crystallin than control astrocytes, but in postnatal Fukuyama congenital muscular dystrophy, astrocytes reacted more to these antibodies and displayed beading of processes. Moreover, vimentin was positive in the astrocytes of two postnatal Fukuyama congenital muscular dystrophy patients. This astrocytic appearance may suggest immaturity of astrocytes in Fukuyama congenital muscular dystrophy. Astrocytes exhibiting beaded cytoplasmic processes were prominent at the subpia of the cortex and around vessels. The authors hypothesize that these immature astrocytes are unable to participate in the function of the cortical basement membrane, which is defective in Fukuyama congenital muscular dystrophy. Studies of neurons and meninges were similar to those of control subjects.     

Epilepsy in patients with advanced Fukuyama congenital muscular dystrophy

BackgroundRecent advances in respiratory management have improved survival for patients with Fukuyama congenital muscular dystrophy (FCMD), characterized by congenital muscular dystrophy and brain malformation. Previous studies reported that more than half of patients exhibit seizures in childhood. However, little is known about epilepsy after childhood.MethodsTo elucidate the long-term clinical course of epilepsy, we retrospectively reviewed all medical records in nine patients (6 males, mean age 20.7 years) with FCMD diagnosed between 1981 and 2019.ResultsThe follow-up periods ranged from 6 to 30 years (mean 18.4 years). A total of 75 EEG recordings were available from nine patients. In some patients, EEGs were normal during early childhood but tended to show paroxysmal discharges with age. Overall, epileptic seizures were observed in six patients. Except for one presenting with afebrile seizure at one year of age, the remaining five patients developed epilepsy between 13 and 22 years of age. The most common seizure type was focal impaired awareness seizure. After adolescence, four patients exhibited status epilepticus. Their convulsive movements of the seizures became less prominent with progression of the disease. At the last evaluation, most patients (5/6) had uncontrolled seizures.ConclusionsDespite presence of distinct brain malformation, epileptic seizures may develop after childhood in FCMD patients. Our experience suggests that clinicians should be careful not to overlook epileptic seizures, especially in advanced-stage patients who had profound muscle weakness.     

Muscle regeneration and satellite cells in Fukuyama type congenital muscular dystrophy

To determine the regenerative capability of muscle fibers in Fukuyama type congenital muscular dystrophy (FCMD), muscle biopsies from nine patients were subjected to morphological examination by histochemical and electron microscopic methods. These results were compared with those from six patients with Duchenne muscular dystrophy (DMD) and nine controls. Degenerating and regenerating fibers were not as frequent in FCMD as in DMD, whereas the number of type 2C fibers in the former was about twice that in the latter. On electron microscopy, numerous immature small fibers with disorganized myofibrils, an increased amount of intermediate filaments, large vesicular nuclei, and prominent nucleoli were observed in FCMD. Satellite cells (SCs), which are known to proliferate and contribute to muscle regeneration after myonecrosis, were not increased in number in FCMD. Their incidence, 7.7% +/- 1.8%, was significantly lower than the 16.2% +/- 4.0% in DMD (P less than 0.005). Moreover, the ratio of area of SC nucleus to the overall area of the SC in FCMD, 64.1% +/- 9.7%, was larger than that in DMD, 58.9% +/- 9.3% (P less than 0.005), suggesting that SCs of FCMD were not in an active state. These findings lead to the conclusion that in FCMD the regenerative process is delayed due to either intrinsic or extrinsic factors, such as dense interstitial fibrosis.     

Oxidative stress in the brain of Fukuyama type congenital muscular dystrophy: immunohistochemical study on astrocytes

Astrocytes in the cerebrum and medulla oblongata of cases of Fukuyama type congenital muscular dystrophy were examined by immunohistochemistry of oxidative modification products and free-radical scavenging enzymes because abnormal glia limitans formed by astrocytic end feet is considered to be involved in the genesis of brain lesions of Fukuywama type congenital muscular dystrophy. The study was performed on two fetal cases of Fukuyama type congenital muscular dystrophy of 18 and 20 weeks' gestation and seven patients with Fukuyama type congenital muscular dystrophy ranging in age from 2 to 27 years. Eight age-matched control cases were used. Polymerase chain reaction (PCR) was performed to ascertain the gene phenotype of two child cases, in which prenatal gene analysis was not performed. Astrocytes, especially layer I astrocytes, of postnatal cases of Fukuyama type congenital muscular dystrophy were weakly positivefor Nepsilon-(carboxymethyl)lysine and argpyrimidine, suggesting that they were sensitive to oxidative stress, and the accumulation may be related to the abnormal glia limitans. Secondary increase of manganese (Mn) superoxide dismutase against the increase of free radicals was considered in patients with Fukuyama type congenital muscular dystrophy more than 14 years old considered to be homozygous for founder haplotype: homozygosity was suggested by PCR in two cases. In contrast, expression of Mn superoxide dismutase was decreased in 2- and 6-year-old children with Fukuyama type congenital muscular dystrophy that were heterozygous. Moreover, accumulation of argpyrimidine was exclusively found in astrocytes of the 2-year-old child that exhibited severe brain lesions. Function of astrocytes might be impaired or immature in severe or heterozygous cases. These results may confirm that astrocytes play an important role in the etiology of the brain lesion.