Sheep and other animals with ceroid-lipofuscinoses: their relevance to Batten disease

Characterising a New Sheep Model of Parkinson's Disease Using Unilateral Intracerebral Injection of 6-Hydroxydopamine Into the Substantia Nigra

New therapeutic agents developed for treating neurological disorders are often tested successfully on rodents. Testing in an appropriate large animal model where there is longer lifespan and comparable brain size to humans should improve translational success and is frequently expected by regulatory bodies. In this project, we aimed to establish a novel sheep model of Parkinson's disease as a large-brained experimental model for translational research. Our objective was to create a sheep model of Parkinson's disease by unilaterally infusing the neurotoxin 6-hydroxydopamine into the substantia nigra pars compacta. This approach, previously used to induce parkinsonism in rat and non-human primate models, causes dopaminergic imbalance and induces rotational behaviour in quadrupeds challenged with dopaminergic receptor agonists. In the present sheep study, the mixed dopamine receptor agonist apomorphine, 0.25 mg/kg, and dopamine D2 agonist ropinirole, 0.16 mg/kg, were used to induce rotational behaviour and confirm dopamine depletion. Behavioural signs were then measured and characterised in the field using automated movement tracking with simultaneous video recordings. Post-mortem, the extent of the 6-hydroxydopamine lesions was evaluated through tyrosine hydroxylase immunohistochemistry and quantifying levels of catecholamines (dopamine, 3,4-dihydroxyphenylacetic acid and homovanilic acid) quantified using high-performance liquid chromatography. Our new sheep model of Parkinson's disease using 6-hydroxydopamine is safe and offers a number of regulatory, ethical and financial advantages over non-human primate 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine models. It provides a platform to evaluate novel antiparkinsonian agents and medical devices in a large brain with the promise of greater success for translation into clinical application.

Batten disease through different in vivo and in vitro models: A review

Batten disease consists of a family of primarily autosomal recessive, progressive neuropediatric disorders, also known as neuronal ceroid lipofuscinoses (NCLs). These pathologies are characterized by seizures and visual, cognitive and motor decline, and premature death. The pathophysiology of this rare disease is still unclear despite the years of trials and financial aids. This paper has reviewed advantages and limits of in vivo and in vitro models of Batten disease from murine and larger animal models to primitive unicellular models, until the most recently developed patient-derived induced pluripotent stem cells. For each model advantages, limits and applications were analyzed. The first prototypes investigated were murine models that due to their limits were replaced by larger animals. In vitro models gradually replaced animal models for practical, cost, and ethical reasons. Using induced pluripotent stem cells to study neurodegeneration is a new way of studying the disease, since they can be distinguished into differentiating elements like neurons, which are susceptible to neurodegeneration. In vivo and in vitro models have contributed to clarifying to some extent the pathophysiology of the disease. The collection and sharing of suitable human bio samples likely through biobanks can contribute to a better understanding, prevention, and to identify possible treatment strategies of Batten disease.

The Sheep as a Large Animal Model for the Investigation and Treatment of Human Disorders

Simple Summary

We review the value of large animal models for improving the translation of biomedical research for human application, focusing primarily on sheep.

Abstract

An essential aim of biomedical research is to translate basic science information obtained from preclinical research using small and large animal models into clinical practice for the benefit of humans. Research on rodent models has enhanced our understanding of complex pathophysiology, thus providing potential translational pathways. However, the success of translating drugs from pre-clinical to clinical therapy has been poor, partly due to the choice of experimental model. The sheep model, in particular, is being increasingly applied to the field of biomedical research and is arguably one of the most influential models of human organ systems. It has provided essential tools and insights into cardiovascular disorder, orthopaedic examination, reproduction, gene therapy, and new insights into neurodegenerative research. Unlike the widely adopted rodent model, the use of the sheep model has an advantage over improving neuroscientific translation, in particular due to its large body size, gyrencephalic brain, long lifespan, more extended gestation period, and similarities in neuroanatomical structures to humans. This review aims to summarise the current status of sheep to model various human diseases and enable researchers to make informed decisions when considering sheep as a human biomedical model.

Current Insights in Elucidation of Possible Molecular Mechanisms of the Juvenile Form of Batten Disease

The neuronal ceroid lipofuscinoses (NCLs) collectively constitute one of the most common forms of inherited childhood-onset neurodegenerative disorders. They form a heterogeneous group of incurable lysosomal storage diseases that lead to blindness, motor deterioration, epilepsy, and dementia. Traditionally the NCL diseases were classified according to the age of disease onset (infantile, late-infantile, juvenile, and adult forms), with at least 13 different NCL varieties having been described at present. The current review focuses on classic juvenile NCL (JNCL) or the so-called Batten (Batten-Spielmeyer-Vogt; Spielmeyer-Sjogren) disease, which represents the most common and the most studied form of NCL, and is caused by mutations in the CLN3 gene located on human chromosome 16. Most JNCL patients carry the same 1.02-kb deletion in this gene, encoding an unusual transmembrane protein, CLN3, or battenin. Accordingly, the names CLN3-related neuronal ceroid lipofuscinosis or CLN3-disease sometimes have been used for this malady. Despite excessive in vitro and in vivo studies, the precise functions of the CLN3 protein and the JNCL disease mechanisms remain elusive and are the main subject of this review. Although the CLN3 gene is highly conserved in evolution of all mammalian species, detailed analysis of recent genomic and transcriptomic data indicates the presence of human-specific features of its expression, which are also under discussion. The main recorded to date changes in cell metabolism, to some extent contributing to the emergence and progression of JNCL disease, and human-specific molecular features of CLN3 gene expression are summarized and critically discussed with an emphasis on the possible molecular mechanisms of the malady appearance and progression.

ATP13A2 missense variant in Australian Cattle Dogs with late onset neuronal ceroid lipofuscinosis

The neuronal ceroid lipofuscinoses (NCLs) are lysosomal storage disorders characterized by progressive neurodegeneration and declines in neurological functions. Pathogenic sequence variants in at least 13 genes underlie different forms of NCL, almost all of which are recessively inherited. To date 13 sequence variants in 8 canine orthologs of human NCL genes have been found to occur in 11 dog breeds in which they result in progressive neurological disorders similar to human NCLs. Canine NCLs can serve as models for preclinical evaluation of therapeutic interventions for these disorders. In most NCLs, the onset of neurological signs occurs in childhood, but some forms have adult onsets. Among these is CLN12 disease, also known as Kufor-Rakeb syndrome, PARK9, and spastic paraplegia78. These disorders result from variants in ATP13A2 which encodes a putative transmembrane ion transporter important for lysosomal function. Three Australian Cattle Dogs (a female and two of her offspring) were identified with a progressive neurological disorder with an onset of clinical signs at approximately 6 years of age. The affected dogs exhibited clinical courses and histopathology characteristic of the NCLs. Whole genome sequence analysis of one of these dogs revealed a homozygous c.1118C > T variant in ATP13A2 that predicts a nonconservative p.(Thr373Ile) amino acid substitution. All 3 affected dogs were homozygous for this variant, which was heterozygous in 42 of 394 unaffected Australian Cattle Dogs, the remainder of which were homozygous for the c.1118C allele. The high frequency of the mutant allele in this breed suggests that further screening for this variant should identify additional homozygous dogs and indicates that it would be advisable to perform such screening prior to breeding Australian Cattle Dogs.

Engineering Large Animal Species to Model Human Diseases

Animal models are an important resource for studying human diseases. Genetically engineered mice are the most commonly used species and have made significant contributions to our understanding of basic biology, disease mechanisms, and drug development. However, they often fail to recreate important aspects of human diseases and thus can have limited utility as translational research tools. Developing disease models in species more similar to humans may provide a better setting in which to study disease pathogenesis and test new treatments. This unit provides an overview of the history of genetically engineered large animals and the techniques that have made their development possible. Factors to consider when planning a large animal model, including choice of species, type of modification and methodology, characterization, production methods, and regulatory compliance, are also covered. © 2016 by John Wiley & Sons, Inc.

Genetically engineered livestock for biomedical models

To commemorate Transgenic Animal Research Conference X, this review summarizes the recent progress in developing genetically engineered livestock species as biomedical models. The first of these conferences was held in 1997, which turned out to be a watershed year for the field, with two significant events occurring. One was the publication of the first transgenic livestock animal disease model, a pig with retinitis pigmentosa. Before that, the use of livestock species in biomedical research had been limited to wild-type animals or disease models that had been induced or were naturally occurring. The second event was the report of Dolly, a cloned sheep produced by somatic cell nuclear transfer. Cloning subsequently became an essential part of the process for most of the models developed in the last 18 years and is stilled used prominently today. This review is intended to highlight the biomedical modeling achievements that followed those key events, many of which were first reported at one of the previous nine Transgenic Animal Research Conferences. Also discussed are the practical challenges of utilizing livestock disease models now that the technical hurdles of model development have been largely overcome.

Experimental therapies in the neuronal ceroid lipofuscinoses

The neuronal ceroid lipofuscinoses represent a group of severe childhood lysosomal storage diseases. With at least 13 identified variants they are the most common cause of inherited neurodegeneration in children. These diseases share common pathological characteristics including motor problems, vision loss, seizures, and cognitive decline, culminating in premature death. Currently, no form of the disease can be treated or cured, with only palliative care to minimise discomfort. This review focuses on current and potentially ground-breaking clinical trials, including small molecule, enzyme replacement, stem cell, and gene therapies, in the development of effective treatments for the various disease subtypes. This article is part of a Special Issue entitled: "Current Research on the Neuronal Ceroid Lipofuscinoses (Batten Disease)".

Translational neurophysiology in sheep: measuring sleep and neurological dysfunction in CLN5 Batten disease affected sheep

Creating valid mouse models of slowly progressing human neurological diseases is challenging, not least because the short lifespan of rodents confounds realistic modelling of disease time course. With their large brains and long lives, sheep offer significant advantages for translational studies of human disease. Here we used normal and CLN5 Batten disease affected sheep to demonstrate the use of the species for studying neurological function in a model of human disease. We show that electroencephalography can be used in sheep, and that longitudinal recordings spanning many months are possible. This is the first time such an electroencephalography study has been performed in sheep. We characterized sleep in sheep, quantifying characteristic vigilance states and neurophysiological hallmarks such as sleep spindles. Mild sleep abnormalities and abnormal epileptiform waveforms were found in the electroencephalographies of Batten disease affected sheep. These abnormalities resemble the epileptiform activity seen in children with Batten disease and demonstrate the translational relevance of both the technique and the model. Given that both spontaneous and engineered sheep models of human neurodegenerative diseases already exist, sheep constitute a powerful species in which longitudinal in vivo studies can be conducted. This will advance our understanding of normal brain function and improve our capacity for translational research into neurological disorders.

Partial correction of the CNS lysosomal storage defect in a mouse model of juvenile neuronal ceroid lipofuscinosis by neonatal CNS administration of an adeno-associated virus serotype rh.10 vector expressing the human CLN3 gene

Juvenile neuronal ceroid lipofuscinosis (JNCL or CLN3 disease) is an autosomal recessive lysosomal storage disease resulting from mutations in the CLN3 gene that encodes a lysosomal membrane protein. The disease primarily affects the brain with widespread intralysosomal accumulation of autofluorescent material and fibrillary gliosis, as well as the loss of specific neuronal populations. As an experimental treatment for the CNS manifestations of JNCL, we have developed a serotype rh.10 adeno-associated virus vector expressing the human CLN3 cDNA (AAVrh.10hCLN3). We hypothesized that administration of AAVrh.10hCLN3 to the Cln3(Δex7/8) knock-in mouse model of JNCL would reverse the lysosomal storage defect, as well as have a therapeutic effect on gliosis and neuron loss. Newborn Cln3(Δex7/8) mice were administered 3 × 10(10) genome copies of AAVrh.10hCLN3 to the brain, with control groups including untreated Cln3(Δex7/8) mice and wild-type littermate mice. After 18 months, CLN3 transgene expression was detected in various locations throughout the brain, particularly in the hippocampus and deep anterior cortical regions. Changes in the CNS neuronal lysosomal accumulation of storage material were assessed by immunodetection of subunit C of ATP synthase, luxol fast blue staining, and periodic acid-Schiff staining. For all parameters, Cln3(Δex7/8) mice exhibited abnormal lysosomal accumulation, but AAVrh.10hCLN3 administration resulted in significant reductions in storage material burden. There was also a significant decrease in gliosis in AAVrh.10hCLN3-treated Cln3(Δex7/8) mice, and a trend toward improved neuron counts, compared with their untreated counterparts. These data demonstrate that AAVrh.10 delivery of a wild-type cDNA to the CNS is not harmful and instead provides a partial correction of the neurological lysosomal storage defect of a disease caused by a lysosomal membrane protein, indicating that this may be an effective therapeutic strategy for JNCL and other diseases in this category.

Characterization of Neuronal Ceroid-Lipofuscinosis in 3 Cats

Three young domestic shorthair cats were presented for necropsy with similar histories of slowly progressive visual dysfunction and neurologic deficits. Macroscopic examination of each cat revealed cerebral and cerebellar atrophy, dilated lateral ventricles, and slight brown discoloration of the gray matter. Histologically, there was bilateral loss of neurons within the limbic, motor, somatosensory, visual, and, to a lesser extent, vestibular systems with extensive astrogliosis in the affected regions of all 3 cases. Many remaining neurons and glial cells throughout the entire central nervous system were distended by pale yellow to eosinophilic, autofluorescent cytoplasmic inclusions with ultrastructural appearances typical of neuronal ceroid-lipofuscinoses (NCLs). Differences in clinical presentation and neurological lesions suggest that the 3 cats may have had different variants of NCL. Molecular genetic characterization in the 1 cat from which DNA was available did not reveal any plausible disease-causing mutations of the CLN1 ( PPT1), CLN3, CLN5, CLN8, and CLN10 ( CTSD) genes. Further investigations will be required to identify the mutations responsible for NCLs in cats.

Large animal models for Batten disease: a review

The neuronal ceroid lipofuscinoses, collectively referred to as Batten disease, make up a group of inherited childhood disorders that result in blindness, motor and cognitive regression, brain atrophy, and seizures, ultimately leading to premature death. So far more than 10 genes have been implicated in different forms of the neuronal ceroid lipofuscinoses. Most related research has involved mouse models, but several naturally occurring large animal models have recently been discovered. In this review, we discuss the different large animal models and their significance in Batten disease research.

High expression of disease-related Cln6 in the cerebral cortex, purkinje cells, dentate gyrus, and hippocampal ca1 neurons

Mutations in the CLN6 gene cause a variant form of late infantile neuronal ceroid lipofuscinosis, a relentless neurodegenerative disease that is inherited as an autosomal recessive trait in humans and in the naturally occurring nclf mouse strain. The CLN6 protein is localized in the endoplasmic reticulum, but it has an unknown function. To develop a molecular understanding of neurodegeneration induced by mutations in CLN6, we examined the spatial and temporal distribution of Cln6 mRNA expression in murine brain. By using Northern blot and tissue qPCR array techniques, a single Cln6 transcript was detected throughout the adult brain, with greatest expression in the cerebellum and hypothalamus. Real-time qPCR showed 2.4-4-fold increases in Cln6 mRNA levels in the cortex and cerebellum during the first 28 days of life, with less prominent enhancement of expression in the hippocampus. In situ hybridization analyses demonstrated Cln6 expression in brainstem, dentate gyrus, and hippocampal neurons of newborn P0 mice. From P14 onward, Cln6 expression is widely distributed throughout the brain and is most prominent in cells of cortical layers II-VI, the Purkinje cell layer, dentate gyrus, and hippocampal CA1 region of adult mice. In different regions of the brain in P0 and P28 nclf mice, the Cln6 mRNA abundance was reduced by 30-40% compared with control mice. These findings implicate Cln6 in the survival and maturation of specific neuronal populations during development and make it possible to compare regional Cln6 expression with the distribution of subsequent pathology.

Accumulation of glial fibrillary acidic protein and histone H4 in brain storage bodies of Tibetan terriers with hereditary neuronal ceroid lipofuscinosis

The neuronal ceroid lipofuscinoses (NCLs) are inherited neurodegenerative diseases characterized by massive accumulation of autofluorescent storage bodies in neurons and other cells. A late-onset form of NCL occurs in Tibetan terrier dogs. Gel electrophoretic analyses of isolated storage body proteins from brains of affected dogs indicated that a protein of approximately 50 kDa was consistently prominent and a 16 kDa component was present in some brain storage body preparations. Mass spectral analysis identified the 50 kDa protein as glial fibrillary acidic protein (GFAP), isoform 2. GFAP identification was supported by immunoblot and immunohistochemical analyses. Histone H4 was the major protein in the 16 kDa component. Specific accumulation of GFAP and histone H4 in storage bodies has not been previously reported for any of the NCLs. Tibetan terrier NCL may be the canine correlate of one of the human adult-onset NCLs for which the genetic bases and storage body compositions have not yet been determined.

Activation of non-neuronal cells within the prenatal developing brain of sheep with neuronal ceroid lipofuscinosis

The neuronal ceroid lipofuscinoses (NCLs, Batten disease) are fatal inherited lysosomal storage diseases of children characterized by increasing blindness, seizures and profound neurodegeneration but the mechanisms leading to these pathological changes remain unclear. Sheep with a CLN6 form that have a human-like brain and disease progression are invaluable for studying pathogenesis. A study of preclinical pathology in these sheep revealed localized glial activation at only 12 days of age, particularly in cortical regions that subsequently degenerate. This has been extended by examining fetal tissue from 60 days of gestation onwards. A striking feature was the presence of reactive astrocytes and the hypertrophy and proliferation of perivascular cells noted within the developing white matter of the cerebral cortex 40 days before birth. Astrocytic activation was evident within the cortical gray matter 20 days before birth, and was confined to the superficial laminae 12 days after birth. Clusters of activated microglia were detected in upper neocortical gray matter laminae shortly after birth. Neuronal development in affected sheep was undisturbed at these early ages. This prenatal activation of non-neuronal cells within the affected brain indicates the onset of pathogenesis during brain development and that an ordered sequence of glial activation precedes neurodegeneration.

A missense mutation (c.184C>T) in ovine CLN6 causes neuronal ceroid lipofuscinosis in Merino sheep whereas affected South Hampshire sheep have reduced levels of CLN6 mRNA

The neuronal ceroid lipofuscinoses (NCLs, Batten disease) are a group of fatal recessively inherited neurodegenerative diseases of humans and animals characterised by common clinical signs and pathology. These include blindness, ataxia, dementia, behavioural changes, seizures, brain and retinal atrophy and accumulation of fluorescent lysosome derived organelles in most cells. A number of different variants have been suggested and seven different causative genes identified in humans (CLN1, CLN2, CLN3, CLN5, CLN6, CLN8 and CTSD). Animal models have played a central role in the investigation of this group of diseases and are extremely valuable for developing a better understanding of the disease mechanisms and possible therapeutic approaches. Ovine models include flocks of affected New Zealand South Hampshires and Borderdales and Australian Merinos. The ovine CLN6 gene has been sequenced in a representative selection of these sheep. These investigations unveiled the mutation responsible for the disease in Merino sheep (c.184C>T; p.Arg62Cys) and three common ovine allelic variants (c.56A>G, c.822G>A and c.933_934insCT). Linkage analysis established that CLN6 is the gene most likely to cause NCL in affected South Hampshire sheep, which do not have the c.184C>T mutation but show reduced expression of CLN6 mRNA in a range of tissues as determined by real-time PCR. Lack of linkage precludes CLN6 as a candidate for NCL in Borderdale sheep.

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.

Membrane trafficking and mitochondrial abnormalities precede subunit c deposition in a cerebellar cell model of juvenile neuronal ceroid lipofuscinosis

Background

JNCL is a recessively inherited, childhood-onset neurodegenerative disease most-commonly caused by a ~1 kb CLN3 mutation. The resulting loss of battenin activity leads to deposition of mitochondrial ATP synthase, subunit c and a specific loss of CNS neurons. We previously generated Cln3^Δex7/8 knock-in mice, which replicate the common JNCL mutation, express mutant battenin and display JNCL-like pathology.

Results

To elucidate the consequences of the common JNCL mutation in neuronal cells, we used P4 knock-in mouse cerebella to establish conditionally immortalized CbCln3 wild-type, heterozygous, and homozygous neuronal precursor cell lines, which can be differentiated into MAP-2 and NeuN-positive, neuron-like cells. Homozygous CbCln3^Δex7/8 precursor cells express low levels of mutant battenin and, when aged at confluency, accumulate ATPase subunit c. Recessive phenotypes are also observed at sub-confluent growth; cathepsin D transport and processing are altered, although enzyme activity is not significantly affected, lysosomal size and distribution are altered, and endocytosis is reduced. In addition, mitochondria are abnormally elongated, cellular ATP levels are decreased, and survival following oxidative stress is reduced.

Conclusions

These findings reveal that battenin is required for intracellular membrane trafficking and mitochondrial function. Moreover, these deficiencies are likely to be early events in the JNCL disease process and may particularly impact neuronal survival.

Selectivity and types of cell death in the neuronal ceroid lipofuscinoses

Cloning of the individual genes that are mutated in the neuronal ceroid lipofuscinoses (NCLs), or Batten disease, has opened up new avenues of research into the pathogenesis of these fatal autosomal recessive storage disorders. Genetically accurate mouse models have now been generated for each major form of the disorder, together with several variant forms. Ongoing analysis of these mice is revealing significant new data about the staging and progression of disease phenotypes. Combined with data from human autopsy tissues and large animal models, it is now clear that neurodegeneration is initially selective in the NCL CNS, targeting specific regions and particular cell populations. There is also evidence of selective glial activation that appears to precede obvious neurodegeneration, becoming more widespread with disease progression. Currently, there is debate over the mechanisms of cell death that operate in each form of NCL, with evidence of both apoptosis and autophagy. It is likely that these mechanisms may encompass a spectrum of cell death events, depending upon the specific context of each neuronal population. Taken together, these data have significant clinical implications for the development and targeting of appropriate therapeutic strategies, and for providing the landmarks to judge their efficacy.

First cases of animal diseases published since 2000. 6. First update of dog diseases

In 2003, Veterinary Quarterly started with the publication of a series of articles reviewing first reports on animal diseases. The articles are arranged in order of animal species. They are regularly updated adding overlooked as well as new first reports. This article is the first update of a review on "first cases" of dog diseases. The following five cases are discussed: Dermatitis in a dog associated with an unidentified Toxoplasma gondii-like parasite. Gastrointestinal cryptosporidiosis in a puppy. Mucinous variant of rete testis adenocarcinoma. Neuronal ceroid-lipofuscinosis in a Labrador Retriever. Salivary gland basal cell adenocarcinoma. After a short introduction, the bibliographical data, the abstract of the author(s) and some additional information derived from the article are given.

First cases of animal diseases published since 2000. 4. Horses

In this fourth article of a series of papers listing first case reports of animal diseases published since 2000, the following six cases of horse diseases are discussed: Disseminated metastatic intramedullary melanoma. Lipoma of the extensor tendon sheaths. Meningoencephalomyelitis in a neonatal foal due to Salmonella agona infection. Neuronal ceroid lipofuscinosis. Placentitis due to Rhodococcus equi infection. Right atrial diverticulum in a foal. After a short introduction, the bibliographical data, the abstract of the author(s), and some additional information derived from the article are given. The article will be regularly updated adding overlooked as well as new first reports.

Mutations in a novel CLN6-encoded transmembrane protein cause variant neuronal ceroid lipofuscinosis in man and mouse

The CLN6 gene that causes variant late-infantile neuronal ceroid lipofuscinosis (vLINCL), a recessively inherited neurodegenerative disease that features blindness, seizures, and cognitive decline, maps to 15q21-23. We have used multiallele markers spanning this approximately 4-Mb candidate interval to reveal a core haplotype, shared in Costa Rican families with vLINCL but not in a Venezuelan kindred, that highlighted a region likely to contain the CLN6 defect. Systematic comparison of genes from the minimal region uncovered a novel candidate, FLJ20561, that exhibited DNA sequence changes specific to the different disease chromosomes: a G-->T transversion in exon 3, introducing a stop codon on the Costa Rican haplotype, and a codon deletion in exon 5, eliminating a conserved tyrosine residue on the Venezuelan chromosome. Furthermore, sequencing of the murine homologue in the nclf mouse, which manifests recessive NCL-like disease, disclosed a third lesion-an extra base pair in exon 4, producing a frameshift truncation on the nclf chromosome. Thus, the novel approximately 36-kD CLN6-gene product augments an intriguing set of unrelated membrane-spanning proteins, whose deficiency causes NCL in mouse and man.

Fine mapping of ovine ceroid lipofuscinosis confirms orthology with CLN6

The neuronal ceroid lipofuscinoses (NCLs) are lysosomal storage diseases with severe neurodegenerative pathology. An ovine model (OCL) has well defined parallels with the human disease at a biochemical and pathological level. The gene for OCL is located in the chromosomal region OAR 7q13-15. This region is syntenic with HSA 15q21-23 suggesting that OCL and CLN6 represent mutations in orthologous genes. New microsatellite markers were used for refinement of the OCL critical region. YAC clones that span the critical region have been isolated and comparative gene mapping confirms that the regions for CLN6 and OCL are equivalent.

Ceroid-lipofuscinosis in a Cocker Spaniel dog

A neurodegenerative storage disease identified as ceroid-lipofuscinosis by light, fluorescence, and electron microscopic examinations was diagnosed in a 4-year-old female Cocker Spaniel dog with progressive ataxia and proprioceptive deficits. Stored pigment was found within neurons of the brain and spinal cord and in smooth muscle cells of the urinary bladder and small muscular arteries. The microscopic findings resembled those found in six other cases of generalized ceroid-lipofuscinosis in this breed. However, the brown discoloration of the intestines, which was the major gross lesion observed in those cases, was not found. This is the first report of the disease in Argentina.

Splicing variants in sheep CLN3, the gene underlying juvenile neuronal ceroid lipofuscinosis

Mutations in different genes underlie different forms of the neuronal ceroid lipofuscinoses (NCLs, Batten disease). Subunit c of mitochondrial ATP synthase specifically accumulates in most of them, including the juvenile CLN3 form and a sheep form orthologous to CLN6. Products of these genes are likely to be components of a complex or pathway for subunit c turnover, and their expression may be cross-regulated. Different bands, some with different subcellular distributions, were detected by antisera against different regions of CLN3 on Western blots of sheep tissues. Affected liver blots were the same as controls but a specific 50-kDa band was at higher concentration in affected brain homogenates than in controls. Others have also reported bands reacting differently to different CLN3 antibodies. When the 3' end of sheep CLN3 cDNA was amplified by RT-PCR, four mRNA splicing variants were found. Different CLN3 splicing variants at the 5' end of the human cDNA have been reported. These mRNA splicing variants may account the variation of epitope distribution and the different subcellular locations of the CLN3 gene product(s). The predicted size of the unmodified CLN3 protein is 48 kDa. Significantly higher molecular weight bands may correspond to oligomers of a CLN3 isoform or to a CLN3 isoform tightly bound to another protein.

In vitro culture of neurons from sheep with Batten disease

Specific storage of mitochondrial ATP synthase subunit c occurs in most forms of Batten disease, including the ovine form, but its relationship to the characteristic neurodegeneration is not clear. Storage occurs in most cell types but only neurons are functionally affected. Neurons were cultured from control and affected sheep. Ewes were superovulated and inseminated, and embryos were collected, frozen, stored, and later transplanted into surrogate dams for gestation at times to suit experimental demands. The optimal fetal age for cultures was investigated, from 50 to 125 days. There were no differences between control and affected embryos in this period of rapid growth. At 50 days brains consist of smooth-surfaced hemispheres and cerebellum with no obvious demarcation between gray and white matter. At 90 days they are like miniature adult brains. From 200 to 600 million viable cells were recovered from each fetus, regardless of age. DMEM/F12 with B27 was the most practical medium tested. Cell viability was not as good in medium containing serum. Treatment of surfaces with polylysine aided neuron adhesion. No developmental or viability differences were observed between normal and affected neuron cultures. At plating out cells were rounded. A day later single process outgrowths began. After 4 days these were over 200 microm and by Day 6 had created a network. Most neurons were bipolar. Neurons from 50 to 90-day old fetuses persisted in culture for over 100 days.

An early-onset congenic strain of the motor neuron degeneration (mnd) mouse

The mouse mutant motor neuron degeneration (mnd/mnd) has been proposed as a model of neuronal ceroid lipofuscinosis (NCL) on the basis of widespread abnormal accumulating lipopigment and neuronal and retinal degeneration. Clinically, the mutant on a C57Bl/6 genetic background shows a progressive motor abnormality starting by 6 months of age, with death prior to 12 months. When mnd is outcrossed to the AKR/J genetic background, ca. 40% of the mnd/mnd F2 progeny show early onset (onset by 4.5-5 months and death by 7 months). A congenic strain of mnd has now been produced by eight generations of backcross onto the AKR background. Mice on this background show average onset at 4 months, and most are moribund prior to 5.5 months. The early onset appears to correlate with levels of abnormal accumulating material, and should prove useful in elucidating NCL neurodegenerative mechanisms.

Progress toward positional cloning of ovine neuronal ceroid lipofuscinosis, a model of the human late-infantile variant CLN6

The neuronal ceroid lipofuscinoses (NCLs) are lysosomal storage diseases with severe neurodegenerative pathology. An ovine model (OCL) has well-defined parallels with the human disease at the biochemical and pathological levels. The gene for OCL is located in the chromosomal region OAR7q13-15. This region is syntenic with HAS15q21-23, suggesting that OCL and CLN6 represent mutations in orthologous genes. New microsatellite markers have been developed enabling further refinement of the OCL critical region.

Molecular basis of the neuronal ceroid lipofuscinoses: mutations in CLN1, CLN2, CLN3, and CLN5

The neuronal ceroid lipofuscinoses (NCLs), also referred to as Batten disease, are a group of neurodegenerative disorders characterised by the accumulation of an autofluorescent lipopigment in many cell types. Different NCL types are distinguished according to age of onset, clinical phenotype, ultrastructural characterisation of the storage material, and chromosomal location of the disease gene. At least eight genes underlie the NCLs, of which four have been isolated and mutations characterised: CLN1, CLN2, CLN3, CLN5. Two of these genes encode lysosomal enzymes, and two encode transmembrane proteins, at least one of which is likely to be in the lysosomal membrane. The basic defect in the NCLs appears to be associated with lysosomal function.

Batten disease: four genes and still counting

The neuronal ceroid lipofuscinoses (NCLs, also known as Batten disease) are the most common childhood neurodegenerative disease. They are a group of inherited neurodegenerative disorders characterized by the accumulation of autofluorescent storage material in many cell types. Clinical features include seizures, psychomotor deterioration, and blindness, the ages and order of onset of which differ for each NCL type. An increasing number of subtypes caused by mutations in different genes are now recognized. With the advent of molecular genetics the basic genetic defect underlying each NCL phenotype is being determined, thus shedding light on the molecular basis of the NCLs and opening the way for the development of effective treatment. Four genes have been identified to date. The function of two of these is known and suggests that the primary defect in the NCLs lies in lysosomal proteolysis, the first example of this type of disease. However, since the function of the other two genes remains elusive, and at least four more genes remain to be identified, the molecular basis underlying the NCLs may be more complex than originally predicted.

Rate of accumulation of Luxol Fast Blue staining material and mitochondrial ATP synthase subunit 9 in motor neuron degeneration mice

The rate of accumulation of Luxol Fast Blue staining material in the hippocampus of motor neuron degeneration (mnd/mnd) mice, a model of Batten Disease, was quantitated. Stained material increased linearly up to 8 months of age. A quantitative immunoassay was used to measure levels of mitochondrial ATP synthase subunit 9 in brain and liver of mnd/mnd mice. Levels of subunit 9 increased progressively throughout the lifespan of mnd/mnd mice reaching levels approximately 5-fold higher than in control animals. The rate of accumulation of subunit 9 is not consistent with any simple complete or partial degradation defect that is constant throughout the animal's life. Two more complicated models are discussed which are consistent with the observed accumulation rate of subunit 9.

Ovine neuronal ceroid lipofuscinosis: a large animal model syntenic with the human neuronal ceroid lipofuscinosis variant CLN6

The neuronal ceroid lipofuscinoses (NCLs) are a group of inherited degenerative neurological diseases affecting children. A number of non-allelic variants have been identified within the human population and the genes for some of these have recently been identified. The underlying mechanism for the neuropathology remains an enigma; however, pioneering studies with the naturally occurring ovine model (OCL) have led to the proposal that these diseases represent lesions in specific hydrophobic protein degradation pathways. In this study, we show linkage between OCL and microsatellite markers on OAR 7q13-15. Using interspecies chromosome painting we establish that OAR 7q13-15 is syntenic with human chromosome 15q21-23, the region which was recently defined as the location of a newly identified late infantile variant (CLN6). We propose that our ovine model represents a mutation in the gene orthologous to that mutated in the human late infantile variant CLN6. The ovine linkage flock, consisting of 56 families, represents a powerful resource for positional cloning of this NCL gene. The availability of such a large animal model will have important implications for experimentation in downstream corrective therapies.

Lysosomal storage diseases of animals: an essay in comparative pathology

A wide variety of inherited lysosomal hydrolase deficiencies have been reported in animals and are characterized by accumulation of sphingolipids, glycolipids, oligosaccharides, or mucopolysaccharides within lysosomes. Inhibitors of a lysosomal hydrolase, e.g., swainsonine, may also induce storage disease. Another group of lysosomal storage diseases, the ceroid-lipofuscinoses, involve the accumulation of hydrophobic proteins, but their pathogenesis is unclear. Some of these diseases are of veterinary importance, and those caused by a hydrolase deficiency can be controlled by detection of heterozygotes through the gene dosage phenomenon or by molecular genetic techniques. Other of these diseases are important to biomedical research either as models of the analogous human disease and/or through their ability to help elucidate specific aspects of cell biology. Some of these models have been used to explore possible therapeutic strategies and to define their limitations and expectations.

Turnover of F1F0-ATP synthase subunit 9 and other proteolipids in normal and Batten disease fibroblasts

Fibroblasts derived from patients with late infantile neuronal ceroid lipofucsinosis (NCL) and from a mouse model of NCL are similar to cells in intact animals in that they accumulate subunit 9 of mitochondrial F1F0-ATP synthase (F-ATPase) (Tanner, A., Dice, J.F., Cell Biol. Int. 19 (1995) 71-75). We now report no differences in the synthetic rates of F-ATPase subunit 9 in such affected cells when compared to control cells. However, the degradation rates of F-ATPase subunit 9 are reduced in both the affected human and mouse cells. This reduced degradation applies only to subunit 9 and the homologous vacuolar ATPase subunit among five distinct, reproducible proteolipid bands analyzed. Approximately 15% of newly synthesized F-ATPase subunit 9 is rapidly degraded in control cells, but this rapidly degraded component is absent in both the human and mouse NCL fibroblasts. At confluence, when the accumulated F-ATPase subunit 9 transiently disappears from human NCL fibroblasts, there is an increased degradation of all proteolipids. The pathway of degradation that is enhanced at confluence is likely to correspond to lysosomal macroautophagy. We confirmed that lysosomes were able to degrade F-ATPase subunit 9 after endocytosis of radiolabeled mitochondria. Human NCL fibroblasts were less active than control cells in this lysosomal degradation of endocytosed F-ATPase subunit 9. However, this difference was not specific for F-ATPase subunit 9 since it also applied to total endocytosed mitochondrial protein. We conclude that degradation of F-ATPase subunit 9 can occur by multiple pathways and that a mitochondrial pathway of proteolysis is defective in the late infantile human and mouse forms of NCL.

The motor neuron degeneration (mnd) gene acts intrinsically in motor neurons and peripheral fibroblasts

In motor neuron degeneration (mnd/mnd) mice, multiple cell types develop cytopathology and motor neurons degenerate prematurely. Here, to investigate whether the expression of mnd within affected cells is responsible, we analyzed the evolution of cellular pathology in aggregation chimeras containing cells of both mnd/mnd and +/+ genotypes. In addition, skin fibroblasts were maintained in vitro in the absence of other cell types and examined for their disease manifestation. In the chimeras, neuronal genotype was identified by expression of an unrelated transgene. Consistent with an intrinsic action of mnd, the genotype and phenotype of motor neurons correlated perfectly. In addition, abnormal lipopigment accumulation, signifying the disease phenotype, evolved in the cultured fibroblasts. We conclude that neurons and fibroblasts develop pathological abnormalities in response to intrinsic expression of the mnd mutation. Further, as cellular pathology is not attenuated in the chimeric environment, it is unlikely that mnd and its human counterparts, neuronal caroid lipofuscinoses, will be responsive to a treatment strategy involving transplantation of normal cells.

Expression and activity of L-Myc in normal mouse development

To determine the role of L-Myc in normal mammalian development and its functional relationship to other members of the Myc family, we determined the normal patterns of L-myc gene expression in the developing mouse by RNA in situ hybridization and assessed the phenotypic impact of L-Myc deficiency produced through standard gene targeting methodology. L-myc transcripts were detected in the developing kidney and lung as well as in both the proliferative and the differentiative zones of the brain and neural tube. Despite significant expression of L-myc in developing mouse tissue, homozygous null L-myc mice were found to be viable, reproductively competent, and represented in expected frequencies from heterozygous matings. A detailed histological survey of embryonic and adult tissues, characterization of an embryonic neuronal marker, and measurement of cellular proliferation in situ did not reveal any congenital abnormalities. The lack of an apparent phenotype associated with L-Myc deficiency indicates that L-Myc is dispensable for gross morphological development and argues against a unique role for L-Myc in early central nervous system development as had been previously suggested. Although overlapping expression patterns among myc family members raise the possibility of complementation of L-Myc deficiency by other Myc oncoproteins, compensatory changes in the levels of c- and/or N-myc transcripts were not detected in homozygous null L-myc mice.

Recent advances in the molecular genetics of the neuronal ceroid lipofuscinoses

Major advances in the molecular genetic analysis of the neuronal ceroid lipofuscinoses (NCL) have recently been made: the genes for two major types have been identified and the chromosomal location for a third defined. CLN1, the gene for infantile NCL (Santavuori-Haltia disease) encodes palmitoyl protein thioesterase (PPT). Most patients (75% of disease chromosomes) have the same point mutation. In contrast, CLN3, the gene for juvenile NCL (Batten or Spielmeyer-Vogt-Sjögren disease) is not a previously known gene, nor does its product display homology to any previously described proteins. The same 1 kb genomic deletion is present in the majority of patients (81% of disease chromosomes). CLN5, the gene for Finnish variant late infantile NCL, has been mapped to 13q and should be identified in the near future. The gene for late-infantile NCL (Jansky-Bielschowsky disease) has not yet been localized to a chromosome despite intensive research. It is likely that this type of NCL is caused by mutations in more than one gene each resulting in the same phenotype.

Batten disease (ceroid-lipofuscinosis): the enigma of subunit c of mitochondrial ATP synthase accumulation

Ceroid-lipofuscinosis is an inherited neurodegenerative disease of human beings and domestic animals characterized by the accumulation in neurons and other cells of a fluorescent lipopigment. In the ovine form of disease, subunit c of mitochondrial ATP synthase is the dominant accumulated metabolite ( > 50%). It also accumulates significantly in the late infantile and juvenile forms of the human disease and several other animal forms. Evidence is accumulating that the underlying biochemical defect may be associated with mitochondria. The extreme hydrophobicity of subunit c and its propensity to aggregate with lipids into regular multilamellar arrays that cannot be catabolised may reflect an initial defect not necessarily associated with faulty proteolysis. This hypothesis extends an earlier one that subunit c accumulated due to a defect in its catabolic pathway.

The neuronal ceroid-lipofuscinoses

The neuronal ceroid-lipofuscinoses, a group of progressive neurodegenerative diseases in children and in adults, have now been recognized for some 90 years, and the childhood forms represent one of the largest groups of progressive neurodegenerative diseases in children. Apart from a core group of major clinical forms-the infantile, the late-infantile, the juvenile, and the adult forms--numerous atypical patients afflicted with neuronal ceroid-lipofuscinosis have now been identified, constituting 10% to 20% of all patients with neuronal ceroid-lipofuscinosis. These "atypical" patients have, over the past 10 years, prompted the suggestion of 15 atypical variants or minor syndromes, many of them displaying the lipopigments of classic curvilinear and fingerprint ultrastructure, but others displaying granular osmiophilic deposits. The former lipopigments contain the subunit C of the mitochondrial adenosine triphosphate synthase, but lipopigments of the granular osmiophilic deposits including the classic infantile type Santavuori-Haltia, apparently do not, the latter type exhibiting sphingolipid activator proteins. The nosologic significance of both the subunit C of the adenosine triphosphate synthase and the sphingolipid activator proteins, although they make up a considerable amount of the crude auto-fluorescent lipopigments in neuronal ceroid-lipofuscinosis, is still unclear. In spite of numerous pathogenetic principles invoked, such as a defect in lipid peroxidation, abnormalities of dolichols and dolichol phosphates, and defects in protease inhibitors, precise pathogenesis and etiology of the neuronal ceroid-lipofuscinoses remain elusive. Recent promising molecular genetic studies have, however, revealed the gene for infantile neuronal ceroid-lipofuscinosis, CLN1, on chromosome 1p32; the gene for juvenile neuronal ceroid-lipofuscinosis, CLN3, on chromosome 16p12.1-11.2; and the gene for a Finnish variant of late-infantile neuronal ceroid-lipofuscinosis, CLN5, on chromosome 13q31-32. The genes for classic late-infantile neuronal ceroid-lipofuscinosis, CLN2, and for adult neuronal ceroid-lipofuscinosis, CLN4, have not been located, the former having been excluded from chromosomes 1 and 16. However, the gene products of the normal allelic forms have not yet been identified. A considerable number of sporadic animal models is now available, largely equivalent to the juvenile and infantile forms of neuronal ceroid-lipofuscinosis, with those of the English setter and the South Hampshire sheep evaluated best. Recently, several mouse models have been added to this list of autosomal-recessive models, again the one most thoroughly studied being the motor-neuron disease mouse. Progress has also been made in the prenatal diagnosis of neuronal ceroid-lipofuscinosis: now the infantile, late-infantile, and juvenile forms can be recognized prenatally by a combined genetic and electron microscopic approach.

Neuronal ceroid-lipofuscinosis in a cat

Neuronal ceroid-lipofuscinosis was diagnosed in a young adult domestic short-haired cat euthanatized because of severe progressive neurologic disease. Clinical signs included blindness, seizures, and decreased mentation. An autofluorescent pigment, identified as ceroid-lipofuscin by electron microscopy and staining properties, was found within neurons of the central and peripheral nervous systems. A diffuse reactive astrocytosis accompanied by multifocal microgliosis was visible in all areas of the brain. Retinal atrophy with intraneuronal lipopigment accumulation was also identified. Contrary to the human neuronal ceroid-lipofuscinoses, pigment deposition appeared to be restricted to neural tissues.

Genetics of primary and timing effects in the mnd mouse

The mnd mouse shows a spontaneous adult-onset hereditary neurological disease, with motor abnormality by 6 months of age, progressing to severe spastic paralysis and premature death. The disease is autosomal recessive, with heterozygote effects seen under stress. It maps to mouse chromosome (chr) 8. Histopathology with Nissl stains documents substantial abnormalities of upper and lower motor neurons, and there is retinal degeneration beginning in the first month, even without light exposure. Increasing levels of autofluorescent lipopigment are found in both neuronal and non-neuronal tissues as the mnd mice age. Recently, NCL-like inclusions and accumulating subunit c have also been described. When mnd is outcrossed to the AKR/J genetic background, ca. 40% of the mnd/mnd F2 progeny show early onset (onset by 4.5-5 months and death by 7 months.) This accelerated timing effect seems to be strain-specific, and unlinked to the mnd gene itself. Our current working hypothesis is that the timing effect is due to 2 or 3 unlinked dominant genes with incomplete penetrance at any single locus. In a combined RFLP/PCR fragment genetic analysis, the strongest deviation from the expected ratio of AKR vs B6 alleles occurs with markers on proximal half of chr 1. Additional loci on chrs 5 and 10 may also be involved. The mechanism of interaction of these modifying genes with the primary mnd gene may offer new therapeutic avenues.

Comparative biology of the neuronal ceroid-lipofuscinoses (NCL): an overview

Multiple forms of ceroid-lipofuscinosis occur in human beings and animals. They are characterized by brain and retinal atrophy associated with selective necrosis of neurons. This neurodegenerative disease appears associated with the disease process rather than storage of fluorescent lipopigment per se, and there is now growing evidence that pathogenesis may involve mitochondria rather than a primary defect of lysosomal catabolism. Of the forms of ceroid-lipofuscinosis studied, most but not all reflect accumulation of subunit c of mitochondrial ATP synthase. If there is a common denominator between all forms other than the presence of fluorescent lipopigment, then it may be the accumulation of hydrophobic protein. Analogous diseases in animals can be expected to reflect the same spectrum of biochemical changes, and they warrant in-depth study to help understand the pathogenesis and heterogeneity of the group.

Immunocytochemical studies in the ceroid-lipofuscinoses (Batten disease) using antibodies to subunit c of mitochondrial ATP synthase

Immunocytochemistry, using antibodies against subunit c of mitochondrial ATP synthase, has been carried out in the ovine, canine, late infantile, and adult forms of ceroid-lipofuscinosis. Intensity of staining varied depending on the particular disease, species, fixation regime, and the antibody used. Differential staining of storage cytosomes in neurons of affected sheep and those in the late infantile patient suggested exposure of different epitopes. This was supported by the variable staining using two different antibodies in ovine, late infantile, and adult onset (Kufs) diseases. Immunostaining of muscle in the late infantile, and muscle and ear cartilage in affected sheep can assist diagnosis but positive results may depend on the age of the patient, at least in the latter species. In these tissues there was immunostaining of structures not identified by histochemical or fluorescence microscopy in addition to storage cytosomes that could be identified by these means. Poor or no immunostaining occurred with canine tissues. At the ultrastructural level, storage cytosomes but not other organelles stained with the immunogold method.

Batten disease and the ATP synthase subunit c turnover pathway: raising antibodies to subunit c

Analysis of storage bodies in the ceroid-lipofuscinoses (Batten disease) has demonstrated a high protein content suggestive of a proteinosis. Direct N-terminal sequencing has shown that subunit c of mitochondrial ATP synthase is specifically stored in the disease in sheep and cattle, and in the human late infantile and juvenile diseases, as well as in 3 breeds of dogs. No differences have been found between the stored subunit c and that in normal mitochondria. No other mitochondrial components are stored. Different proteins, sphingolipid activator proteins (SAPs or saposins) A and D, are stored in the infantile disease. Linkage studies have shown that different forms of ceroid-lipofuscinosis are coded for on different genes on different chromosomes. The genes for subunit c, its production, its insertion into mitochondria, and mitochondrial function are normal. This suggests that underlying the various forms of the disease is a family of lesions in the normal pathway of subunit c turnover, after its normal insertion into the ATP synthase complex. Antibodies to subunit c offer one way of mapping that pathway and detecting the sites of lesions. Specific antibodies have been raised against stored subunit c, using a liposomal adjuvant system which proved superior to classical adjuvants. These antibodies are also useful diagnostically, both in Western blotting and in immunocytochemistry.

Tissue culture loading test with storage granules from animal models of neuronal ceroid-lipofuscinosis (Batten disease): testing their lysosomal degradability by normal and Batten cells

Storage granules (SGs) from ovine and canine models of Batten disease were found to be easily phagocytosed by four cell types studied. The cell types tested were human fibroblasts and peripheral monocytes (control and from a late infantile Batten disease patient), rat C6 cell line, and neonatal cardiomyocytes. The phagocytosed SGs elicited an increase in acid phosphatase activity which was localized in the phagolysosome. After phagocytosis SGs were followed for various times ranging from 7 to 21 days and were found to be of unchanged density (phase contrast), autofluorescence, and ultrastructural appearance. These findings point to their undergradability, or very low degree of degradability, in phagolysosomes in both normal or Batten cultured cells. The Batten disease SGs are not toxic and did not cause any adverse affect on the host cells. Either the normal clearance rate from lysosomes is too slow to be measured by this technique or subunit c accumulation in lysosomes need not result from a primary lysosomal protease defect. Subunit c may aggregate, because of the lack of some normally preventive factor, resulting in a physical barrier to the degradation of this highly apolar molecule.

The neuronal ceroid-lipofuscinoses (Batten disease): comparative aspects

The ceroid-lipofuscinoses are a group of inherited neurodegenerative diseases of human beings characterized by the accumulation of a fluorescent lipopigment in neurons and other cells within the body. There is usually atrophy of both brain and retina with preferential loss of particular neurons. Biochemically, the diseases divide into at least two groups, i.e. those that accumulate subunit c of mitochondrial ATP synthase and those that do not. Dolichol pyrophosphate linked oligosaccharides are also present in storage material. As the underlying biochemical anomalies are not known, the various clinicopathological entities are classified on clinical grounds, by age of onset and, to a lesser extent, by the course of the disease. The best recognized diseases are infantile, late infantile, early juvenile, juvenile and adult onset forms but other variants occur indicating considerable heterogeneity within the group. The infantile, late infantile and juvenile diseases are not allelic. Analogous diseases occur in a variety of animal species. That in the sheep has been extensively studied as a model of the human disease and is the prototype subunit c storage disease.