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Neuronal ceroid lipofuscinosis (nclf), a new disorder of the mouse linked to chromosome 9.

The neuronal ceroid lipofuscinoses (NCLs) comprise a set of at least 6 distinct human and an unknown number of animal diseases characterized by storage of proteolipids in lysosomes of many cell types. By unknown mechanisms, this accumulation leads to or is associated with severe neuronal and retinal degeneration. The genes for 3 human NCLs, infantile, late infantile, and juvenile, have been cloned. The first murine form of NCL, the motor neuron degeneration (mnd) mouse, has been described and mapped to proximal Chromosome 8. Here we describe a second genetic variant of NCL in the mouse, neuronal ceroid lipofuscinosis, nclf. These mice exhibited a phenotype that was almost exactly the same as that observed in mnd/mnd mice. Homozygous nclf mice developed progressive retinal atrophy early in life and become paralyzed at around 9 months of age. They accumulated luxol fast blue staining material in cytoplasm of neurons and many other cell types. Ultrastructurally, affected lysosomes had a "finger print pattern" with membranous material arranged in "pentalaminar" patterns. Affected mice developed severe cerebral gliosis in late stages of their disease. They also had severe Wallerian degeneration of long tracts in spinal cord and brain stem, lesions that accounted for the distinctive upper motor neuron signs displayed by both nclf/nclf and mnd/mnd mice. By crossing nclf/nclf mice with CAST/Ei mice, linkage analysis of nclf with respect to SSLP markers was performed, showing that nclf is located on Chromosome 9 between D9Mit164 and D9Mit165, in a region that is homologous with human Ch 15q21, where the gene for one variant of late infantile NCL, CLN6, recently has been mapped. The genes for two proteolipids known to be stored in lysosomes of animals and people with NCL were also mapped in this study and found not to map to the mnd or nclf loci nor to any mouse locus homologous to any known human NCL disease locus.

Animals↗

Decreased membrane fluidity of lymphocytes from patients with juvenile neuronal ceroid-lipofuscinosis.

The storage material in neuronal ceroid-lipofuscinoses (NCL) apparently contains breakdown products of membrane lipids. The storage could be due to an unknown enzyme deficiency in the degradation of lipids or to an alteration of the lipid substrate within the plasma membrane. We investigated the membrane fluidity of intact lymphocytes in juvenile NCL (McKusick no. 20420) by steady-state fluorescence polarization. Fluorescent probes used were diphenylhexatriene (DPH), trimethylammonium-DPH (TMA-DPH), and a set of n-(9-anthroyloxy) fatty acids. Membrane fluidity was decreased in NCl (n = 12) vs. control lymphocytes when measured with the labels DPH, TMA-DPH, 6-, 7-(9-anthroyloxy) stearic acid, and 16- (9-anthroyloxy) palmitic acid (P less than 0.05). In order to check for the influence of anticonvulsants on membrane fluidity, we investigated 17 epileptic patients (without NCL) treated with anticonvulsants. Membrane fluidity was increased in these patients when measured with DPH and with the anthroyloxy probes. Our results indicate a decreased fluidity of the outer membrane leaflet in NCL lymphocytes which is independent of the effect of anticonvulsants.

Adolescent↗

Evidence for processing of dolichol-linked oligosaccharides in patients with neuronal ceroid-lipofuscinosis.

In agreement with reports from other laboratories, we have shown that patients with the juvenile or late infantile forms of neuronal ceroid-lipofuscinosis (NCL) have greatly increased levels (5-fold to 20-fold) of dolichyl pyrophosphoryl oligosaccharides in their cerebral gray matter. Oligosaccharides containing 2 GlcNAc residues and 3 to 9 mannose residues were liberated by mild acid hydrolysis. The oligosaccharide profile given by brain tissue from 2 patients with infantile NCL was markedly different from that of late infantile and juvenile NCL brain, with Man9GlcNAc2 as the most abundant component and decreasing amounts of Man8- Man7- and Man6GlcNAc2. By contrast, Man5GlcNAc2 was the most abundant oligosaccharide present in all juvenile NCL brain samples analyzed. Both the susceptibility of the isolated Man5GlcNAc2 to endoglucosaminidase H digestion and permethylation analysis clearly indicated that it is not an intermediate in the biosynthesis of Glc3Man9GlcNAc2-PP-dolichol but has undergone catabolism, probably either in the endoplasmic reticulum or in the Golgi apparatus. Treatment of cultured skin fibroblasts for 7 days with N-methyldeoxynojirimycin, a potent inhibitor of the endoplasmic reticulum processing enzymes glucosidase I and II, resulted in an accumulation of the same Man5GlcNAc2-PP-dolichol species that was elevated in juvenile NCL brain. The level in untreated fibroblasts was undetectable, suggesting that inhibition of processing glucosidases has interfered with the regulation and compartmentalization of lipid-linked oligosaccharides.

1-Deoxynojirimycin↗

Classification of the neuronal ceroid-lipofuscinoses: expansion of the atypical forms.

The neuronal ceroid-lipofuscinoses (NCL) are a group of different genetic diseases. The major types of NCL are expressed by six forms which represent different clinicopathologic and genetic forms. These are CLN-1, Infantile; CLN-2, Late Infantile; CLN-3, Juvenile; CLN-4, Adult-Recessive; CLN-5, Adult-Dominant; and CLN-6, Early Juvenile. The distinction between CLN-4 and CLN-5 is still disputatious. CLN-6 has been called CLN-5. A seventh classification of NCL represents from 12 to 20% of those afflicted. This group consists of an extensive array of atypical types of ceroid-lipofuscin accumulation in the secondary lysosomes of neurons and cells of other tissues (e.g., skin, conjunctiva, and lymphocytes) or by presumed clinical and genetic relationships. The authors have identified 15 atypical subtypes of NCL. These as a group are here described as a seventh form. Further biochemical, molecular, and genetic studies will identify more precisely the phenotypic and genotypic expression of these "minor" forms of NCL.

Adolescent↗

First-trimester diagnosis of juvenile neuronal ceroid lipofuscinosis by demonstration of fingerprint inclusions in chorionic villi.

One of the most common hereditary, progressive encephalopathies in children--juvenile neuronal ceroid lipofuscinosis (NCL)--lacks methods for carrier detection and prenatal diagnosis. A transcervical chorionic villus biopsy was performed at 9 completed weeks in a fetus at high risk of this disease. The syncytiotrophoblast of the chorionic villi contained fingerprint inclusions similar to those observed in various cells from children with this disease. Together with previous reports of second-trimester diagnosis in a case with late-infantile NCL (MacLeod et al., 1984, 1985), the presence of typical inclusions in placental tissue sampled at term in the infantile NCL (Rapola et al., 1987) and the lack of pathological alterations in one fetus at high risk of juvenile NCL and without clinical and morphological signs of disease at the age of 15 months (Kohlschutter et al., 1989), our findings strongly indicate that an early prenatal diagnosis of (juvenile) NCL is possible.

Chorionic Villi↗

Developmental changes in the expression of neuronal ceroid lipofuscinoses-linked proteins.

Neuronal ceroid lipofuscinoses (NCL) form a distinct group of storage diseases where the normal development of the central nervous system is interrupted and neurons of the neocortex begin to degenerate. Mutations in genes encoding three lysosomal enzymes are the causes for three early-onset forms of NCLs: palmitoyl-protein thioesterase 1 (PPT1) is deficient in human infantile NCL, tripeptidyl peptidase 1 (TTP1) in late-infantile NCL, and cathepsin D in congenital ovine NCL. We wanted to compare the developmental expression profiles of these enzymes in rat brain. In conclusion, the PPT1 expression pattern differed from the two other lysosomal enzymes implicated in NCL diseases, thus suggesting a distinctive role for PPT1 in brain development.

Aminopeptidases↗

The adult and a new late adult forms of neuronal ceroid lipofuscinosis.

Three cases of the late adult form of neuronal ceroid lipofuscinosis (NCL) are reported. Two of these are siblings with a late clinical onset at ages 26 and 44 years. The third case, sporadic, has the oldest reported age for the onset of NCL, at 63 years and may be regarded as the first example of the "presenile" form of NCL. The clinical, morphological, histochemical, ultrastructural and genetic features of these three cases are discussed. The literature of the clinicopathological NCL cases with an onset at age of 25 and older is reviewed. The clinical and morphological differences between the late adult form and the presenile form of NCL as well as the difficulties in making the diagnosis are discussed.

Adult↗

Correlations between genotype, ultrastructural morphology and clinical phenotype in the neuronal ceroid lipofuscinoses.

The neuronal ceroid lipofuscinoses (NCLs) are a group of severe neurodegenerative diseases with onset usually in childhood and characterised by the intracellular accumulation of autofluorescent storage material. Within the last decade, mutations that cause NCL have been found in six human genes (CLN1, CLN2, CLN3, CLN5, CLN6 and CLN8). Mutations in two additional genes cause disease in animal models that share features with NCL-CTSD in sheep and mice and PPT2 in mice. Approximately 160 NCL disease-causing mutations have now been described (listed and fully cited in the NCL Mutation Database, http://www.ucl.ac.uk/ncl/ ). Most mutations result in a classic morphology and disease phenotype, but some mutations are associated with disease that is of later onset, less severe or protracted in its course, or with atypical morphology. Seven common mutations exist, some having a worldwide distribution and others associated with families originating from specific geographical regions. This review attempts to correlate the gene, disease-causing mutation, morphology and clinical phenotype for each type of NCL.

Aminopeptidases↗

Neuronal ceroid lipofuscinoses: clinical and EEG findings in a large study of Italian cases.

We reviewed the clinical and EEG features of 30 Italian patients with childhood-onset neuronal ceroid lipofuscinosis (NCL). The outcome and the EEG pattern of the 4 infantile NCL cases were classic, although the age at onset of symptoms varied from 1.0 to 3.5 years. This latter finding is unusual and has not been reported for other Italian patients. Both typical and variant cases of late-infantile NCL (LINCL) were observed. This NCL type represents the most common form in our country, and was the largest group (18 cases) in our study. A particular pseudoperiodic EEG pattern was observed in 15 of the 18 patients with LINCL. This pattern may be useful in early diagnosis, especially if associated with the absence of sleep spindles. In the 8 cases with juvenile NCL, clinical and EEG findings were similar to those reported in the literature.

Child↗

Beta-protein immunoreactivity in brains of patients with neuronal ceroid lipofuscinosis: ultrastructural and biochemical demonstration.

The storage pigment in neuronal ceroid lipofuscinoses (NCL) has a close similarity to age pigment lipofuscin. We studied immunoreactivity of isolated neuronal pigments from the juvenile form of NCL and aging control, using monoclonal antibodies (mAbs) against amyloid beta-protein. Ultrastructural localization of the immunoreactivity demonstrated that in NCL the epitopes are distributed mainly in curvilinear multilamellar arrays of the storage pigments and less in fingerprint profiles, while in aging control they are more homogeneously distributed on age pigment lipofuscin. The different distribution of the epitopes may reflect some catabolic as well as morphologic differences in lysosomes. A unique 31-kDa polypeptide detected on Western blots in NCL possibly derives from the same precursor, amyloid beta-protein precursor (ABPP). ABPP processing may be aberrant in NCL brains, and this can be detected as a 31-kDa polypeptide reactive with the mAbs.

Adolescent↗

The neuronal ceroid-lipofuscinoses: from past to present.

The neuronal ceroid-lipofuscinoses (NCLs) are inherited lysosomal storage diseases and constitute the most common group of children's progressive encephalopathies. Most childhood forms of NCL are clinically characterized by progressive loss of vision as well as mental and motor deterioration, epileptic seizures, and premature death, while the rare adult forms are dominated by dementia. All forms of NCL share common pathomorphological features. Autofluorescent, periodic acid-Schiff- and Sudan black B-positive granules, resistant to lipid solvents, accumulate in the cytoplasm of most nerve cells, and there is progressive and remarkably selective neuronal degeneration and loss. For a long time, the NCLs were grouped under the heading of the "amaurotic family idiocies" and conceived as lipidoses. However, in the late 1980s and 1990s the NCL storage cytosomes were shown to consist largely of two hydrophobic proteins: either subunit c of mitochondrial ATP synthase or sphingolipid activator proteins A and D. Since 1995 numerous mutations in at least seven different genes have been shown to underlie the multiple human and animal forms of NCL. This review discusses the historical evolution of the NCL concept and the impact of the recent biochemical and molecular genetic findings on our views on the classification and pathogenesis of these devastating brain disorders.

Cerebellar Cortex↗

Maintenance in working memory or response selection? Functions of NMDA receptors in the pigeon "prefrontal cortex".

The prefrontal cortex is involved in various aspects of working memory like stimulus maintenance and response selection functions. Neurobehavioral studies and neurocomputational models assume a role for NMDA receptors in prefrontal cortex for maintenance processes, while our previous studies on NMDA receptors in the avian prefrontal cortex-analogue, the nidopallium caudolaterale (NCL), showed them to be involved in response selection functions. Various tasks used in PFC-related research address in fact both functions, so they cannot disambiguate their separate contributions to performance. In order to investigate the role of NMDA receptors in avian NCL for stimulus maintenance and response selection, we trained pigeons in a delayed matching-to sample (DMTS) task, requiring both functions, and a simultaneous matching to sample (SMTS) task, requiring only response selection. After reaching criterion, pigeons had to perform the tasks alternately under local NMDA receptor blockade in NCL (DL-AP5) and after infusion of vehicle (saline solution). Blockade of NCL-based NMDA receptors led to significant increases in error rates in both DMTS and SMTS--compared with the same subjects' performance during training and in the control condition. However, there was no additional increase in errors due to the additional maintenance component, so the impairment appears to be due to deficits in adequate selection of responses, the function necessary for both tasks. We conclude that NMDA receptors in the pigeon NCL participate in response selection rather than stimulus maintenance in tasks requiring the processing of context information.

Animals↗

Progressive myoclonic epilepsy: A clinical, electrophysiological and pathological study from South India.

Progressive myoclonic epilepsy (PME) is a syndrome complex encompassing different diagnostic entities and often cause problems in diagnosis. We describe the clinical, electrophysiological and pathological features of 97 patients with the diagnosis of PME evaluated over 25 years. Case records of confirmed patients of Neuronal ceroid lipofuscinosis (NCL = 40), Lafora body disease (LBD = 38), Myoclonic epilepsy with ragged red fibers (MERRF = 10), and probable Unverricht-Lundberg disease (ULD = 9) were reviewed. The mean age at onset in patients with NCL (n = 40) was 5.9+/-9.1 years (M:F:: 28:12). Subtypes of NCL were: late infantile (n = 19), infantile (n = 8), juvenile (n = 11) and adult (n = 2) NCL. EEG (n = 37) showed varying degree of diffuse slowing of background activity in 94.6% and epileptiform discharges in 81.1% of patients. Slow frequency photic stimulation evoked photo-convulsive response in 5 patients only. Giant SSEP was demonstrated in 7 and VEP study revealed a prolonged P100 (2) and absent waveform (7). Electrophysiological features of neuropathy were present in 3 patients. Presence of PAS and Luxol Fast Blue (LFB) positive, auto fluorescent (AF) ceroid material in brain tissue (n = 12) and electron microscopy of brain (n = 5), skin (n = 28) and muscle (n = 1) samples showing curvilinear and lamellar bodies established the diagnosis. Patients of LBD (mean age of onset at 14.4+/-3.9 years, M:F:: 24:14) with triad of PME symptoms were evaluated. EEG (n = 37) showed variable slowing of background activity in 94.6% and epileptiform discharges in 97.4%. Photosensitivity with fast frequency was observed only in 5 patients. CT (n = 32) and MRI (n = 4) revealed diffuse cortical atrophy. Giant SSEP was demonstrated in 24 patients of LBD while VEP study revealed a prolonged P100 (4) and absent waveform (8). Electrophysiological features of neuropathy were present in one patient. Diagnosis was established by the presence of PAS positive diastase resistant, Lugol's Iodine labeled inclusions in sweat glands of axillary skin (n = 35), brain (n = 2) and liver (n = 1). Ten patients with MERRF (mean age at onset: 14.6+/-5.8 years; M: F:: 3:2) had triad of PME symptoms. Muscle biopsy revealed oxidative reaction product and classical ragged red fibers. In nine patients of PME without cognitive decline, probable diagnosis of ULD (mean age at onset: 13.8+/-9.5 years) was considered after biopsy of skin and/or muscle excluded other forms of PMEs. Neuronal ceroid lipofuscinosis and Lafora body diseases were the common causes of PME in the series from south India. This is one of the largest series from the Indian subcontinent to the best of our knowledge. Photosensitivity is notably less common in LBD/NCL in this series distinctly different from those reported in the literature. Further exploration is required to determine whether different genotype is responsible. Morphological changes were helpful in diagnosis and could be confirmed by biopsy of peripheral tissues like skin and muscle in majority (60%). Electron microscopy was helpful in the diagnosis NCL and MERRF.

Adolescent↗

Cathepsin D-deficient Drosophila recapitulate the key features of neuronal ceroid lipofuscinoses.

Neuronal ceroid lipofuscinoses (NCLs) are a group of lysosomal storage disorders characterized pathologically by neuronal accumulation of autofluorescent storage material and neurodegeneration. An ovine NCL form is caused by a recessive point mutation in the cathepsin D gene, which encodes a lysosomal aspartyl protease. This mutation results in typical NCL pathology with neurodegeneration and characteristic neuronal storage material. We have generated a Drosophila NCL model by inactivating the conserved Drosophila cathepsin D homolog. We report here that cathepsin D mutant flies exhibit the key features of NCLs. They show progressive neuronal accumulation of autofluorescent storage inclusions, which are also positive for periodic acid Schiff and luxol fast blue stains. Ultrastructurally, the storage material is composed of membrane-bound granular electron-dense material, similar to the granular osmiophilic deposits found in the human infantile and ovine congenital NCL forms. In addition, cathepsin D mutant flies show modest age-dependent neurodegeneration. Our results suggest that the metabolic pathway leading to NCL pathology is highly conserved during evolution, and that cathepsin D mutant flies can be used to study the pathogenesis of NCLs.

Amino Acid Sequence↗

A mutation in canine CLN5 causes neuronal ceroid lipofuscinosis in Border collie dogs.

Neuronal ceroid lipofuscinosis (NCL) is a neurodegenerative disease found in Border collie dogs, humans, and other animals. Disease gene studies in humans and animals provided candidates for the NCL gene in Border collies. A combination of linkage analysis and comparative genomics localized the gene to CFA22 in an area syntenic to HSA13q that contains the CLN5 gene responsible for the Finnish variant of human late infantile NCL. Sequencing of CLN5 revealed a nonsense mutation (Q206X) within exon 4 that correlated with NCL in Border collies. This truncation mutation should result in a protein product of a size similar to that of some mutations identified in human CLN5 and therefore the Border collie may make a good model for human NCL. A simple test was developed to enable screening of the Border collie population for carriers so the disease can be eliminated as a problem in the breed.

Amino Acid Sequence↗

Cellular pathology and pathogenic aspects of neuronal ceroid lipofuscinoses.

Lysosomal accumulation of autofluorescent, ceroid lipopigment material in various tissues and organs is a common feature of the neuronal ceroid lipofuscinoses (NCLs). However, recent clinicopathologic and genetic studies have evidenced that NCLs encompass a group of highly heterogeneous disorders. In five of the eight NCL variants distinguished at present, genes associated with the disease process have been isolated and characterized (CLN1, CLN2, CLN3, CLN5, CLN8). Only products of two of these genes, CLN 1 and CLN2, have structural and functional properties of lysosomal enzymes. Nevertheless, according to the nature of the material accumulated in the lysosomes, NCLs in humans as well as natural animal models of these disorders can be divided into two major groups: those characterized by the prominent storage of saposins A and D, and those showing the predominance of subunit c of mitochondrial ATP synthase accumulation. Thus, taking into account the chemical character of the major component of the storage material, NCLs can be classified currently as proteinoses. Of importance, although lysosomal storage material accumulates in NCL subjects in various organs, only brain tissue shows severe dysfunction and cell death, another common feature of the NCL disease process. However, the relation between the genetic defects associated with the NCL forms, the accumulation of storage material, and tissue damage is still unknown. This chapter introduces the reader to the complex pathogenesis of NCLs and summarizes our current knowledge of the potential consequences of the genetic defects of NCL-associated proteins on the biology of the cell.

Adolescent↗

Prenatal ultrastructural diagnosis in the neuronal ceroid-lipofuscinoses.

The neuronal ceroid-lipofuscinoses (NCL) are autosomal-recessive disorders in childhood of unknown enzymatic origin. They can be recognized by the presence of abnormal lipopigments identified by electron microscopy. Based on the study of circulating lymphocytes, individual clinical subtypes of NCL can be correlated. Prenatal diagnosis of NCL with the electron microscope is now feasible for the infantile (Finnish) from (INCL) and late-infantile form (LINCL). INCL-specific granular lipopigments are present in endothelial cells of biopsied chorion stroma vessels of homozygously affected fetuses. In LINCL, disease-typical curvilinear bodies can be identified in uncultured amniotic fluid cells. Prenatal ultrastructural recognition of juvenile NCL (JNCL) is still controversial as only one single case has been reported. Electron microscopic findings can also be corroborated by genetic analysis in INCL and JNCL because the defective genes have been localized to chromosomes 1 and 16, respectively, but not in LINCL. Documentation of the index patients in the family is essential before prenatal diagnosis, and post-abortive confirmation of fetal NCL is also desirable.

Amniotic Fluid↗

Leukocytes in neuronal ceroid-lipofuscinoses: function and apoptosis.

The neuronal ceroid-lipofuscinoses (NCL) are a group of progressive encephalopathies with a fatal course that are mostly of autosomal recessive inheritance. The pathophysiological mechanisms causing the diseases are not known. The characteristic histomorphological feature of the NCL is an abnormal lysosomal accumulation of lipopigments in neural and extraneural cells, including peripheral blood leukocytes. We studied the function of peripheral venous blood immunocompetent cells in ten patients with NCL and in age- and sex-matched controls to determine how, if at all, the accumulation of intracytoplasmic storage material influences the functional capacity of affected tissue. Our results did not reveal any functional impairment of affected cells, but rather suggested a higher turnover rate in NCL. Apoptosis was increased, suggesting that abnormally controlled programmed cell death might play an important role in the pathogenesis of NCL.

Adolescent↗