DARS2 mutations in mitochondrial leucoencephalopathy and multiple sclerosis.

BACKGROUND: Leucoencephalopathy with brain stem and spinal cord involvement and high brain lactate (LBSL) was first defined by characteristic magnetic resonance imaging and spectroscopic findings. The clinical features include childhood or juvenile onset slowly progressive ataxia, spasticity, and dorsal column dysfunction, occasionally accompanied by learning difficulties. Mutations in DARS2, encoding mitochondrial aspartyl-tRNA synthetase, were recently shown to cause LBSL. The signs and symptoms show some overlap with the most common leucoencephalopathy of young adults, multiple sclerosis (MS). OBJECTIVE: To clarify the molecular background of LBSL patients in Finland, and to look for DARS2 mutations in a group of MS patients. METHODS: Clinical evaluation of LBSL patients, DARS2 sequencing and haplotype analysis, and carrier frequency determination in Finland. RESULTS: All eight LBSL patients were compound heterozygotes for DARS2 mutations: all carried R76SfsX5 change, seven had M134_K165del, and one had C152F change. Axonal neuropathy was found in five of the eight patients. The carrier frequencies of the R76SfsX5 and M134_K165del mutations were 1:95 and 1:380, respectively. All patients shared common European haplotypes, suggestive of common European LBSL ancestors. No enrichment of the two common DARS2 mutations was found in 321 MS patients. CONCLUSION: All LBSL patients were compound heterozygotes, which suggests that DARS2 mutation homozygosity may be lethal or manifest as a different phenotype. The authors show here that despite identical mutations the clinical picture was quite variable in the patients. Axonal neuropathy was an important feature of LBSL. DARS2 mutations cause childhood-to-adolescence onset leucoencephalopathy, but they do not seem to be associated with MS.

Insufficient energy and nutrient intake in children with motor disability.

AIM: Children with motor disabilities are at increased risk of compromised bone health due to impaired weight bearing. Poor nutritional status may be an additional risk factor. The aim of this study was to evaluate energy and nutrient intakes in children with motor disability. PATIENTS AND METHODS: Fifty-four children with motor disability (cerebral palsy in 59%) were included. Three-day food diaries were collected and analysed. The results were compared with recommended dietary allowances for age and sex. RESULTS: The median age was 10.9 years. The median energy intake was 76% of the recommendation and <80% in 57% of children. Of the total energy, 17% was from protein, 32% from fat and 50% from carbohydrates. The medians were for calcium intake 142% and for vitamin D intake 76% of the recommendation; serum 25-hydroxy-vitamin D concentrations were low (median 46 nmol/L). Children with low energy intake were shorter and lighter and had more severe motor disability than children with sufficient energy intake. CONCLUSION: Insufficient energy and nutrient intake is common in children with motor disability. This may have adverse health effects especially when associated with low vitamin D intake. Energy and vitamin D supplements should be considered.

Effect of specific immunotherapy with preimmunization against alpha-fetoprotein on a mouse transplantable hepatoma.

Antibodies to autologous alpha-fetoprotein (AFP) were produced in mice by immunization with rat AFP. C57L/J mice with or without such antibodies were inoculated sc or ip with controlled numbers of cells of the syngeneic, AFP-producing, BW 7756 hepatoma. There was a linear relationship between circulating AFP and tumor mass, with elevated AFP being detectable earlier than the tumor. The AFP levels of the immunized mice were generally lower than those of control mice, and tumors could be detected before elevated concentrations of AFP appeared in the circulation. An extensive series of transplantations with varying protocols for immunization did not protect against tumor and did not affect the rate of tumor growth.

Clinical and genetic distinction between Walker-Warburg syndrome and muscle-eye-brain disease.

BACKGROUND: Three rare autosomal recessive disorders share the combination of congenital muscular dystrophy and brain malformations including a neuronal migration defect: muscle-eye-brain disease (MEB), Walker-Warburg syndrome (WWS), and Fukuyama congenital muscular dystrophy (FCMD). In addition, ocular abnormalities are a constant feature in MEB and WWS. Lack of consistent ocular abnormalities in FCMD has allowed a clear clinical demarcation of this syndrome, whereas the phenotypic distinction between MEB and WWS has remained controversial. The MEB gene is located on chromosome 1p32-p34. OBJECTIVES: To establish distinguishing diagnostic criteria for MEB and WWS and to determine whether MEB and WWS are allelic disorders. METHODS: The authors undertook clinical characterization followed by linkage analysis in 19 MEB/WWS families with 29 affected individuals. With use of clinical diagnostic criteria based on Finnish patients with MEB, each patient was categorized as having either MEB or WWS. A linkage and haplotype analysis using 10 markers spanning the MEB locus was performed on the entire family resource. RESULTS: Patients in 11 families were classified as having MEB and in 8 families as WWS. Strong evidence in favor of genetic heterogeneity was obtained in the 19 families. There was evidence for linkage to 1p32-p34 in all but 1 of the 11 pedigrees segregating the MEB phenotype. In contrast, linkage to the MEB locus was excluded in seven of eight of the WWS families. CONCLUSION: These results allow the classification of MEB and WWS as distinct disorders on both clinical and genetic grounds and provide a basis for the mapping of the WWS gene(s).

Pathology of skeletal muscle and impaired respiratory chain function in long-chain 3-hydroxyacyl-CoA dehydrogenase deficiency with the G1528C mutation.

Lactic acidosis and mitochondrial abnormalities have been reported in long-chain 3-hydroxyacyl-CoA dehydrogenase (LCHAD) deficiency. We studied muscle morphology and the respiratory chain function in ten patients with LCHAD deficiency and the G1528C mutation. In eight cases the light microscopy of muscle specimens showed fatty infiltration and fibre degeneration. The degenerated fibres appeared as ragged red fibres in four cases. Electron microscopy revealed enlarged mitochondria often with swollen appearance in four out of seven patients. The number of mitochondria had also increased. Complex I associated enzyme activities in muscle mitochondria were decreased in five out of seven patients, and in three of them Complex II or II + III associated activities were also affected. We suggest that the reason for respiratory chain dysfunction and structural changes of mitochondria is the accumulation of toxic intermediates of fatty acid beta-oxidation in mitochondria. Because these changes may confound the differential diagnostics between LCHAD deficiency and respiratory chain defects, awareness of their frequency is important.

Benign muscular dystrophy with autosomal dominant inheritance.

A slowly progressive myopathy was discovered in a family in four successive generations. Eight patients (four female, four male) from three generations were examined and they showed muscle weakness affecting predominantly proximal, but also distal, muscles. Two patients had unequivocal findings in childhood, the others showed myopathy in their twenties or thirties. Working ability was lost in physically demanding jobs in the thirties, but activities of daily living were still preserved. Elbow contractures, tight heel cords and contractures of the interphalangeal joints were frequent. Serum CK activity was usually mildly elevated and electromyographic examinations revealed myopathic changes. Histopathological changes were compatible with moderately advanced muscular dystrophy in two patients, the six others had mild myopathic changes.

Muscle-eye-brain disease and Fukuyama type congenital muscular dystrophy are not allelic.

Muscle-Eye-Brain disease (MEB) and Fukuyama type congenital muscular dystrophy (FCMD) are clinically similar autosomal recessive diseases, characterized by congenital muscular dystrophy and severe mental retardation, raising the possibility that they might be caused by mutations of the same gene. Recently FCMD was localized to chromosome 9q31-33 by linkage. We performed a linkage study in seven Finnish MEB families with 12 affected patients using markers D9S53, D9S58, D9S59 and HXB. The MEB phenotype was not linked to any of the markers. A multipoint linkage analysis excluded the entire region harboring FCMD. We thus conclude that MEB and FCMD are not allelic.

Merosin-deficient congenital muscular dystrophy with mental retardation and cerebellar cysts unlinked to the LAMA2, FCMD and MEB loci.

We report a case of congenital muscular dystrophy with secondary merosin deficiency, structural involvement of the central nervous system and mental retardation in an 8-year-old girl from a consanguineous family. She had early-onset hypotonia, generalized muscle wasting, with weakness especially of the neck muscles, joint contractures, mental retardation and high creatine kinase. Muscle biopsy showed dystrophic changes with partial deficiency of the laminin alpha(2) chain. Cranial magnetic resonance imaging revealed multiple small cysts in the cerebellum, without cerebral cortical dysplasia or white matter changes. The laminin alpha(2) chain (6q2), Fukuyama type congenital muscular dystrophy (9q31-q33) and muscle-eye-brain disease (1p32-p34) loci were all excluded by linkage analysis. We suggest that this case represents a new entity in the nosology of congenital muscular dystrophy.

Muscle membrane-skeleton protein changes and histopathological characterization of muscle-eye-brain disease.

Muscle-eye-brain disease belongs to congenital muscular dystrophies with central nervous system abnormalities. The etiology of MEB is still unknown, but abnormal immunoreactivity for laminin-2 has been reported. To evaluate disease progression in muscle tissue, 32 biopsy specimens from 17 muscle-eye-brain patients were analysed. The samples of four patients were studied by immunohistochemical techniques and by quantitative Western blotting. The samples showed a great variation in the muscle pathology. Regenerative fibers and mild fiber size variation were present in over 60%. At infancy, necrotic and regenerative fibers were common, while fat infiltration was the most prominent finding in the age group over five years. In quantitative studies, the amount of laminin alpha 2 chain was clearly reduced to 10-20% of normal. In contrast, laminin beta 2 chain was overexpressed in the Western blotting studies. These findings may reflect a yet unidentified primary disturbance in the basement membrane composition and function.

Congenital myasthenic syndrome associated with episodic apnea and sudden infant death.

The sudden infant death syndrome has multiple etiologies. Some congenital myasthenic syndromes can cause sudden infant death syndrome by apnea, but the frequency of this etiology is unknown. We report here a young patient with sudden respiratory crises culminating in apnea followed by recovery, against a background of no or variable myasthenic symptoms without dyspnea. One sib without myasthenic symptoms and one sib who only had mild ptosis died previously during febrile episodes. Studies reported by us elsewhere traced the proband's illness to mutations in choline acetyltransferase. Here, we describe in detail the morphologic investigations and electrophysiologic findings, which point to a presynaptic defect in acetylcholine resynthesis or vesicular filling, in the proband. Analysis of DNA from a sib who previously died of sudden infant death syndrome revealed the same choline acetyltransferase mutation. Thus, mutations in choline acetyltransferase may be a cause of sudden infant death syndrome as, theoretically, could other presynaptic myasthenic disorders.

Palmitate oxidation in muscle mitochondria of patients with the juvenile form of neuronal ceroid-lipofuscinosis.

The finding that the intracellular storage material in juvenile neuronal ceroid lipofuscinosis (JNCL) consists of the subunit c of ATP synthase prompted us to study energy conservation in JNCL patients. The activities of respiratory chain enzymes in isolated muscle mitochondria from 8 JNCL cases were normal, but oxidation of palmitate was reduced in 6 patients. The degree of reduction was related to the age of the patients. None of the patients had clinical symptoms or laboratory findings of impaired energy conservation, which suggest that the reduced palmitate oxidation was not associated with a major defect in fatty acid oxidation.

PEHO syndrome (progressive encephalopathy with edema, hypsarrhythmia, and optic atrophy): neuroradiologic findings.

PURPOSE: To investigate the radiologic characteristics of the clinical progressive encephalopathy with edema, hypsarrhythmia, and optic atrophy (PEHO) symptom complex. This complex is nonspecific, but within this syndrome, a subgroup with a defined neuropathologic phenotype and apparently autosomal recessive inheritance exists. METHODS: Brain CT or MR studies were performed on 21 patients with the clinical PEHO syndrome. Their previous neuroradiologic studies were re-evaluated. RESULTS: Twelve patients (group A) showed uniform changes with early progressive brain atrophy accentuated infratentorially, and abnormal myelination. The gyral pattern was normal. Brain atrophy of nine patients (group B) differed by being less progressive, supra- rather than infratentorial, and often combined with abnormal gyral formation. CONCLUSIONS: Postmortem studies permitted correlation of radiographic and morphologic findings in three cases. Two autopsied group A patients were compatible with the true PEHO syndrome, while one group B patient was incompatible. Group A seems to correspond to the core group of the PEHO syndrome. During a patient's life, a suggestive diagnosis of the true PEHO syndrome is thus feasible, although neuropathologic studies are needed for a conclusive diagnosis.

Infantile-onset spinocerebellar ataxia: MR and CT findings.

PURPOSE: To report the MR and CT findings in a hereditary disease, infantile-onset spinocerebellar ataxia (IOSCA). METHODS: We studied the brains of 17 patients with infantile-onset spinocerebellar ataxia with CT and/or MR to determine the presence of cerebellar and brain stem atrophy and parenchymal lesions. RESULTS: Cerebellar cortical atrophy was seen in 13 patients. The degree of atrophy correlated with increasing age and clinical deterioration. Brain stem atrophy was seen in 8 patients. It was never severe, and the basis pontis was not flattened even in the most severe cases. Hyperintense lesions were noted within the white matter of cerebellum, in the dentate nuclei, and in the middle cerebellar peduncles in 3 patients. The upper cervical cord was seen in 9 patients and showed mild to moderate atrophy in 4. The basal ganglia and cerebral hemispheres were normal, except in 2 patients transient cortical and subcortical lesions developed during episodes of status epilepticus; mild cortical brain atrophy subsequently developed. CONCLUSION: The brain MR and CT findings of patients with infantile-onset spinocerebellar ataxia correspond to the neuropathologic entities of cerebellar cortical atrophy, olivopontocerebellar atrophy, and spinocerebellar atrophy. The appearance of the findings followed a uniform time sequence from cerebellar cortical atrophy in the early stage of the disease to olivopontocerebellar atrophy and spinocerebellar atrophy in the later stage. The severity of atrophy correlated with clinical deterioration.

Neuroradiologic findings in children with mitochondrial disorders.

PURPOSE: We report the neuroradiologic findings in 25 children with various mitochondrial diseases. METHODS: Twenty-two children with a mitochondrial disorder had MR imaging of the brain and three children had CT studies. In all cases, the diagnosis was based on examination of muscle morphology, analysis of oxygen consumption and respiratory chain enzyme activity in isolated muscle mitochondria, and analysis of rearrangements of the mitochondrial DNA. RESULTS: Fifteen patients were found to have the classical syndromes of mitochondrial diseases. Four children had Kearns-Sayre syndrome, but only one had the typical neuroradiologic findings of basal ganglia and brain stem lesions, T2 hyperintensity of the cerebral white matter, and cerebellar atrophy; the others had nonspecific or normal findings. Eight patients had Leigh syndrome, and all showed changes in the putamina. Involvement of the caudate nuclei, globus pallidi, thalami, and brain stem was common, and diffuse supratentorial white matter T2 hyperintensity was seen in two of these patients. Three patients had mitochondrial encephalopathy with lactic acidosis and strokelike episodes (MELAS), with infarctlike lesions that did not correspond to the vascular territories. Ten children with complex I or IV deficiencies and abnormal muscle morphology had nonspecific imaging findings, such as atrophy and abnormal or delayed myelination. One patient with combined complex I and IV deficiency had extensive white matter changes. None of the patients with clinical encephalopathy had normal findings. CONCLUSION: MR imaging is helpful in the diagnosis of the classical mitochondrial diseases; however, nonspecific findings are common.

Infantile onset spinocerebellar ataxia with sensory neuropathy (IOSCA): neuropathological features.

Infantile onset spinocerebellar ataxia (IOSCA, MIM 271245) is a recessively inherited, progressive neurological disease, which we have described in 19 Finnish patients. The clinical symptoms of IOSCA include ataxia, athetosis, hypotonia, hearing deficit, ophthalmoplegia, sensory neuropathy, female hypogonadism, and epilepsy as a late manifestation. We have mapped the IOSCA locus to 10q24. In our two autopsy cases of IOSCA, the neuropathological findings were almost uniform. The cerebral hemispheres were quite well preserved, but the brain stem and the cerebellum were moderately atrophic. The most severe atrophic changes were seen in the spinal cord: in the dorsal roots, the posterior columns and the posterior spinocerebellar tracts. There was a severe neuronal loss in the dorsal nucleus (Clarke's column) of both cases and slight atrophy of the intermediolateral column in one case. The cerebellar peduncles, the inferior olives, the accessory cuneate nuclei and especially the dentate nuclei were atrophic and gliotic. The eighth cranial nerve and nucleus were atrophic. The ventral pontine nuclei and transverse fibers were slightly affected. Tegmental nuclei and tracts, especially sensory structures, were more severely affected. In mesencephalon, there was atrophy of the oculomotor nuclear complex and periaqueductal gray matter. The cerebellar cortex showed patchy atrophy. Degenerative changes were seen in dorsal root ganglia, and there was a severe axonal loss in the sural nerve. The neuropathological picture of IOSCA thus seems close to that reported in Friedreich's ataxia, another recessively inherited usually childhood-onset ataxia.

Lymphocytic beta-adrenergic receptors in X-linked muscular dystrophy.

Lymphocytic beta-adrenoceptor levels, receptor binding affinity, lymphocytic basal and isoproterenol-stimulated cyclic AMP (cAMP) production and plasma catecholamine levels were studied in 49 patients with neuromuscular diseases and in 10 healthy subjects. Patients with X-linked muscular dystrophy (Duchenne, 13 patients; Becker, 4 patients) showed a significant reduction in lymphocytic beta-adrenoceptor densities (35.9 +/- 2.2 fmol/mg protein vs. 49.6 +/- 3.6 fmol/mg, controls; P less than 0.02), whereas the receptor levels for the patients with spinal muscular atrophy (15), polymyositis (10) and for Duchenne carriers (7) did not differ significantly from the corresponding levels for the control subjects. The reduction in the beta-adrenoceptor density was not correlated with the physical disability of the patients. Lymphocytic beta-adrenoceptor affinity (KD) and basal and isoproterenol-stimulated cAMP levels were all comparable to control subjects' values. Catecholamine levels showed mild inconsistent elevations in various patient groups. The results suggest that reduction in cellular beta-adrenoceptors is characteristic of X-linked muscular dystrophies. Its relationship to the basic gene defect is unknown.

Infantile onset spinocerebellar ataxia with sensory neuropathy: a new inherited disease.

We report the clinical findings in 19 Finnish patients, including six pairs of siblings, with a new, early onset spinocerebellar ataxia. The slowly progressive clinical symptoms manifested between one and two years of age in previously healthy infants. The first manifestation of children at that age was clumsiness and loss of ability to walk. Ataxia, athetosis and muscle hypotonia with loss of deep tendon reflexes were discovered on clinical examination. By school age ophthalmoplegia and hearing loss were diagnosed, while sensory neuropathy developed by adolescence. In addition, an acute crisis with status epilepticus was a late manifestation. We found a marked decrease in sensory nerve condition velocities, a progressive loss of myelinated fibers in sural nerve specimen, and abnormal background activity in EEG with advancing age. The main finding in neuroradiological investigations was cerebellar atrophy. The occurrence of the disease in siblings and lack of manifestations in parents indicate recessive inheritance.

Diagnosis of fatal infantile defects of the mitochondrial respiratory chain: age dependence and postmortem analysis of enzyme activities.

We studied two diagnostic aspects of fatal infantile defects of the mitochondrial respiratory chain: the age dependence of muscle mitochondrial enzyme activities and the reliability of diagnosis from autopsy samples. In morphologically normal quadriceps muscle samples of 46 children between the ages of 3 days and 15 years, activities of complex I plus III (NADH:cytochrome c oxidoreductase) and complex II plus III (succinate:cytochrome c oxidoreductase) increased 2-fold during the first three years of life, while that of complex II (succinate dehydrogenase), complex IV (cytochrome c oxidase), and citrate synthase did not show significant correlation with age. We suggest that these changes are related to age and stress the importance of strictly age-matched controls when diagnosing a mitochondrial disease of early childhood. The value of autopsy samples in diagnostic studies was evaluated by comparing mitochondrial enzyme activities in quadriceps muscle from autopsies and from surgical biopsies. In quadriceps muscle mitochondria, all the enzyme activities studied remained stable for at least 3 h after death. Using age-matched controls and autopsy samples, we diagnosed a respiratory chain enzyme deficiency in two infants, and the defects were confirmed in cultured skin fibroblasts.

Muscle-eye-brain disease: clinical features, visual evoked potentials and brain imaging in 20 patients.

Clinical features, magnetic resonance imaging and visual evoked potentials were analysed and correlated in 20 Finnish patients with muscle-eye-brain disease. Significantly enhanced visual evoked potentials were found in 15 patients (giant in 14 of them). Magnetic resonance images were available in 17 cases. The images of 12 patients with giant visual evoked potentials showed typical brain malformation pachygyria with a nodular cortical surface i.e. cobblestone cortex, midline defect and hypoplastic pons but no significant abnormalities in the grey-white matter. One male had typical structural changes but flat visual evoked potentials. His extreme hydrocephalus with optic nerve compression may explain the findings. No structural changes on magnetic resonance images were found in the remaining four patients; however, in two of them marked alterations in the white matter were found. Three of these patients showed normal and one flat visual evoked potentials. Only one patient with giant visual evoked potentials and typical structural findings on magnetic resonance imaging had changes in a large area in the white matter (several attacks of status epilepticus might have caused the alterations in the white matter). Thus, the combination of giant visual evoked potentials and typical structural changes on magnetic resonance imaging with normal intensities of white matter and deep grey matter seems to be a good marker for patients with muscle-eye-brain disease.

Brain perfusion SPECT in children with frequent fits.

We studied 14 children with frequent fits using 99mTc-HM-PAO single photon emission computed tomography (SPECT). There were 11 patients with partial secondary generalized epilepsy (PSGE) and 3 with Lennox-Gastaut syndrome (LGS). The typical regional cerebral blood flow (rCBF) finding in PSGE was a single area of abnormally low perfused cortex, and that in LGS, multiple hypoperfused areas. Clinically, the LGS patients were more severely affected. SPECT was more sensitive in detecting abnormalities than EEG, CT or MRI. Extensive impairment of rCBF may thus indicate unfavourable development of intellectual performance and poor seizure control.