Clinical and neuroradiological diagnostic aspects of neuronal ceroid lipofuscinoses disorders

Characterization of neurological disease progression in a canine model of CLN5 neuronal ceroid lipofuscinosis

Golden Retriever dogs with a frameshift variant in CLN5 (c.934_935delAG) suffer from a progressive neurodegenerative disorder analogous to the CLN5 form of neuronal ceroid lipofuscinosis (NCL). Five littermate puppies homozygous for the deletion allele were identified prior to the onset of disease signs. Studies were performed to characterize the onset and progression of the disease in these dogs. Neurological signs that included restlessness, unwillingness to cooperate with the handlers, and proprioceptive deficits first became apparent at approximately 12 months of age. The neurological signs progressed over time and by 21 to 23 months of age included general proprioceptive ataxia, menace response deficits, aggressive behaviors, cerebellar ataxia, intention tremors, decreased visual tracking, seizures, cognitive decline, and impaired prehension. Due to the severity of these signs, the dogs were euthanized between 21 and 23 months of age. Magnetic resonance imaging revealed pronounced progressive global brain atrophy with a more than sevenfold increase in the volume of the ventricular system between 9.5 and 22.5 months of age. Accompanying this atrophy were pronounced accumulations of autofluorescent inclusions throughout the brain and spinal cord. Ultrastructurally, the contents of these inclusions were found to consist primarily of membrane‐like aggregates. Inclusions with similar fluorescence properties were present in cardiac muscle. Similar to other forms of NCL, the affected dogs had low plasma carnitine concentrations, suggesting impaired carnitine biosynthesis. These data on disease progression will be useful in future studies using the canine model for therapeutic intervention studies.

Visual system pathology in a canine model of CLN5 neuronal ceroid lipofuscinosis

CLN5 neuronal ceroid lipofuscinosis is a hereditary neurodegenerative disease characterized by progressive neurological decline, vision loss and seizures. Visual impairment in children with CLN5 disease is attributed to a progressive decline in retinal function accompanied by retinal degeneration as well as impaired central nervous system function associated with global brain atrophy. We studied visual system pathology in five Golden Retriever littermates homozygous for the CLN5 disease allele previously identified in the breed. The dogs exhibited signs of pronounced visual impairment by 21-22 months of age. Electroretinogram recordings showed a progressive decline in retinal function primarily affecting cone neural pathways. Altered visual evoked potential recordings indicated that disease progression affected visual signal processing in the brain. Aside from several small retinal detachment lesions, no gross retinal abnormalities were observed with in vivo ocular imaging and histologically the retinas did not exhibit apparent abnormalities by 23 months of age. However, there was extensive accumulation of autofluorescent membrane-bound lysosomal storage bodies in almost all retinal layers, as well as in the occipital cortex, by 20 months of age. In the retina, storage was particularly pronounced in retinal ganglion cells, the retinal pigment epithelium and in photoreceptor cells just interior to the outer limiting membrane. The visual system pathology of CLN5-affected Golden Retrievers is similar to that seen early in the human disease. It was not possible to follow the dogs to an advanced stage of disease progression due to the severity of behavioral and motor disease signs by 23 months of age. The findings reported here indicate that canine CLN5 disease will be a useful model of visual system disease in CLN5 neuronal ceroid lipofuscinosis. The baseline data obtained in this investigation will be useful in future therapeutic intervention studies. The findings indicate that there is a fairly broad time frame after disease onset within which treatments could be effective in preserving vision.

Management of CLN1 Disease: International Clinical Consensus

BACKGROUND

CLN1 disease (neuronal ceroid lipofuscinosis type 1) is a rare, genetic, neurodegenerative lysosomal storage disorder caused by palmitoyl-protein thioesterase 1 (PPT1) enzyme deficiency. Clinical features include developmental delay, psychomotor regression, seizures, ataxia, movement disorders, visual impairment, and early death. In general, the later the age at symptom onset, the more protracted the disease course. We sought to evaluate current evidence and to develop expert practice consensus to support clinicians who have not previously encountered patients with this rare disease.

METHODS

We searched the literature for guidelines and evidence to support clinical practice recommendations. We surveyed CLN1 disease experts and caregivers regarding their experiences and recommendations, and a meeting of experts was conducted to ascertain points of consensus and clinical practice differences.

RESULTS

We found a limited evidence base for treatment and no clinical management guidelines specific to CLN1 disease. Fifteen CLN1 disease experts and 39 caregivers responded to the surveys, and 14 experts met to develop consensus-based recommendations. The resulting management recommendations are uniquely informed by family perspectives, due to the inclusion of caregiver and advocate perspectives. A family-centered approach is supported, and individualized, multidisciplinary care is emphasized in the recommendations. Ascertainment of the specific CLN1 disease phenotype (infantile-, late infantile-, juvenile-, or adult-onset) is of key importance in informing the anticipated clinical course, prognosis, and care needs. Goals and strategies should be periodically reevaluated and adapted to patients' current needs, with a primary aim of optimizing patient and family quality of life.

Ocular Manifestations of Neuronal Ceroid Lipofuscinoses

Neuronal ceroid lipofuscinoses (NCLs) are a group of rare neurodegenerative storage disorders associated with devastating visual prognosis, with an incidence of 1/1,000,000 in the United States and comparatively higher incidence in European countries. The pathophysiological mechanisms causing NCLs occur due to enzymatic or transmembrane defects in various sub-cellular organelles including lysosomes, endoplasmic reticulum, and cytoplasmic vesicles. NCLs are categorized into different types depending upon the underlying cause i.e., soluble lysosomal enzyme deficiencies or non-enzymatic deficiencies (functions of identified proteins), which are sub-divided based on an axial classification system. In this review, we have evaluated the current evidence in the literature and reported the incidence rates, underlying mechanisms and currently available management protocols for these rare set of neuroophthalmological disorders. Additionally, we also highlighted the potential therapies under development that can expand the treatment of these rare disorders beyond symptomatic relief.

Guidelines on the diagnosis, clinical assessments, treatment and management for CLN2 disease patients

Background

CLN2 disease (Neuronal Ceroid Lipofuscinosis Type 2) is an ultra-rare, neurodegenerative lysosomal storage disease, caused by an enzyme deficiency of tripeptidyl peptidase 1 (TPP1). Lack of disease awareness and the non-specificity of presenting symptoms often leads to delayed diagnosis. These guidelines provide robust evidence-based, expert-agreed recommendations on the risks/benefits of disease-modifying treatments and the medical interventions used to manage this condition.

Methods

An expert mapping tool process was developed ranking multidisciplinary professionals, with knowledge of CLN2 disease, diagnostic or management experience of CLN2 disease, or family support professionals. Individuals were sequentially approached to identify two chairs, ensuring that the process was transparent and unbiased. A systematic literature review of published evidence using Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidance was independently and simultaneously conducted to develop key statements based upon the strength of the publications. Clinical care statements formed the basis of an international modified Delphi consensus determination process using the virtual meeting (Within3) online platform which requested experts to agree or disagree with any changes. Statements reaching the consensus mark became the guiding statements within this manuscript, which were subsequently assessed against the Appraisal of Guidelines for Research and Evaluation (AGREEII) criteria.

Results

Twenty-one international experts from 7 different specialities, including a patient advocate, were identified. Fifty-three guideline statements were developed covering 13 domains: General Description and Statements, Diagnostics, Clinical Recommendations and Management, Assessments, Interventions and Treatment, Additional Care Considerations, Social Care Considerations, Pain Management, Epilepsy / Seizures, Nutritional Care Interventions, Respiratory Health, Sleep and Rest, and End of Life Care. Consensus was reached after a single round of voting, with one exception which was revised, and agreed by 100% of the SC and achieved 80% consensus in the second voting round. The overall AGREE II assessment score obtained for the development of the guidelines was 5.7 (where 1 represents the lowest quality, and 7 represents the highest quality).

Conclusion

This program provides robust evidence- and consensus-driven guidelines that can be used by all healthcare professionals involved in the management of patients with CLN2 disease and other neurodegenerative disorders. This addresses the clinical need to complement other information available.

Supplementary Information

The online version contains supplementary material available at 10.1186/s13023-021-01813-5.

A multimodal approach to identify clinically relevant biomarkers to comprehensively monitor disease progression in a mouse model of pediatric neurodegenerative disease

While research has accelerated the development of new treatments for pediatric neurodegenerative disorders, the ability to demonstrate the long-term efficacy of these therapies has been hindered by the lack of convincing, noninvasive methods for tracking disease progression both in animal models and in human clinical trials. Here, we unveil a new translational platform for tracking disease progression in an animal model of a pediatric neurodegenerative disorder, CLN6-Batten disease. Instead of looking at a handful of parameters or a single "needle in a haystack", we embrace the idea that disease progression, in mice and patients alike, is a diverse phenomenon best characterized by a combination of relevant biomarkers. Thus, we employed a multi-modal quantitative approach where 144 parameters were longitudinally monitored to allow for individual variability. We use a range of noninvasive neuroimaging modalities and kinematic gait analysis, all methods that parallel those commonly used in the clinic, followed by a powerful statistical platform to identify key progressive anatomical and metabolic changes that correlate strongly with the progression of pathological and behavioral deficits. This innovative, highly sensitive platform can be used as a powerful tool for preclinical studies on neurodegenerative diseases, and provides proof-of-principle for use as a potentially translatable tool for clinicians in the future.

Synapse alterations precede neuronal damage and storage pathology in a human cerebral organoid model of CLN3-juvenile neuronal ceroid lipofuscinosis

The juvenile form of neuronal ceroid Lipofuscinosis (JNCL) is the most common form within this group of rare lysosomal storage disorders, causing pediatric neurodegeneration. The genetic disorder, which is caused by recessive mutations affecting the CLN3 gene, features progressive vision loss, cognitive and motor decline and other psychiatric conditions, seizure episodes, leading to premature death. Animal models have traditionally aid the understanding of the disease mechanisms and pathology and are very relevant for biomarker research and therapeutic testing. Nevertheless, there is a need for establishing reliable and predictive human cellular models to study the disease. Since patient material, particularly from children, is scarce and difficult to obtain, we generated an engineered a CLN3-mutant isogenic human induced pluripotent stem cell (hiPSC) line carrying the c.1054C → T pathologic variant, using state of the art CRISPR/Cas9 technology. To prove the suitability of the isogenic pair to model JNCL, we screened for disease-specific phenotypes in non-neuronal two-dimensional cell culture models as well as in cerebral brain organoids. Our data demonstrates that the sole introduction of the pathogenic variant gives rise to classical hallmarks of JNCL in vitro. Additionally, we discovered an alteration of the splicing caused by this particular mutation. Next, we derived cerebral organoids and used them as a neurodevelopmental model to study the particular effects of the CLN3^Q352X mutation during brain formation in the disease context. About half of the mutation -carrying cerebral organoids completely failed to develop normally. The other half, which escaped this severe defect were used for the analysis of more subtle alterations. In these escapers, whole-transcriptome analysis demonstrated early disease signatures, affecting pathways related to development, corticogenesis and synapses. Complementary metabolomics analysis confirmed decreased levels of cerebral tissue metabolites, some particularly relevant for synapse formation and neurotransmission, such as gamma-amino butyric acid (GABA). Our data suggests that a mutation in CLN3 severely affects brain development. Furthermore, before disease onset, disease -associated neurodevelopmental changes, particular concerning synapse formation and function, occur.

Therapeutic landscape for Batten disease: current treatments and future prospects

Batten disease (also known as neuronal ceroid lipofuscinoses) constitutes a family of devastating lysosomal storage disorders that collectively represent the most common inherited paediatric neurodegenerative disorders worldwide. Batten disease can result from mutations in 1 of 13 genes. These mutations lead to a group of diseases with loosely overlapping symptoms and pathology. Phenotypically, patients with Batten disease have visual impairment and blindness, cognitive and motor decline, seizures and premature death. Pathologically, Batten disease is characterized by lysosomal accumulation of autofluorescent storage material, glial reactivity and neuronal loss. Substantial progress has been made towards the development of effective therapies and treatments for the multiple forms of Batten disease. In 2017, cerliponase alfa (Brineura), a tripeptidyl peptidase enzyme replacement therapy, became the first globally approved treatment for CLN2 Batten disease. Here, we provide an overview of the promising therapeutic avenues for Batten disease, highlighting current FDA-approved clinical trials and prospective future treatments.

Proteomic mapping of differentially vulnerable pre-synaptic populations identifies regulators of neuronal stability in vivo

Synapses are an early pathological target in many neurodegenerative diseases ranging from well-known adult onset conditions such as Alzheimer and Parkinson disease to neurodegenerative conditions of childhood such as spinal muscular atrophy (SMA) and neuronal ceroid lipofuscinosis (NCLs). However, the reasons why synapses are particularly vulnerable to such a broad range of neurodegeneration inducing stimuli remains unknown. To identify molecular modulators of synaptic stability and degeneration, we have used the Cln3^−/− mouse model of a juvenile form of NCL. We profiled and compared the molecular composition of anatomically-distinct, differentially-affected pre-synaptic populations from the Cln3^−/− mouse brain using proteomics followed by bioinformatic analyses. Identified protein candidates were then tested using a Drosophila CLN3 model to study their ability to modify the CLN3-neurodegenerative phenotype in vivo. We identified differential perturbations in a range of molecular cascades correlating with synaptic vulnerability, including valine catabolism and rho signalling pathways. Genetic and pharmacological targeting of key ‘hub’ proteins in such pathways was sufficient to modulate phenotypic presentation in a Drosophila CLN3 model. We propose that such a workflow provides a target rich method for the identification of novel disease regulators which could be applicable to the study of other conditions where appropriate models exist.

Diagnosis of neuronal ceroid lipofuscinosis type 2 (CLN2 disease): Expert recommendations for early detection and laboratory diagnosis

Neuronal ceroid lipofuscinoses (NCLs) are a heterogeneous group of lysosomal storage disorders. NCLs include the rare autosomal recessive neurodegenerative disorder neuronal ceroid lipofuscinosis type 2 (CLN2) disease, caused by mutations in the tripeptidyl peptidase 1 (TPP1)/CLN2 gene and the resulting TPP1 enzyme deficiency. CLN2 disease most commonly presents with seizures and/or ataxia in the late-infantile period (ages 2-4), often in combination with a history of language delay, followed by progressive childhood dementia, motor and visual deterioration, and early death. Atypical phenotypes are characterized by later onset and, in some instances, longer life expectancies. Early diagnosis is important to optimize clinical care and improve outcomes; however, currently, delays in diagnosis are common due to low disease awareness, nonspecific clinical presentation, and limited access to diagnostic testing in some regions. In May 2015, international experts met to recommend best laboratory practices for early diagnosis of CLN2 disease. When clinical signs suggest an NCL, TPP1 enzyme activity should be among the first tests performed (together with the palmitoyl-protein thioesterase enzyme activity assay to rule out CLN1 disease). However, reaching an initial suspicion of an NCL or CLN2 disease can be challenging; thus, use of an epilepsy gene panel for investigation of unexplained seizures in the late-infantile/childhood ages is encouraged. To confirm clinical suspicion of CLN2 disease, the recommended gold standard for laboratory diagnosis is demonstration of deficient TPP1 enzyme activity (in leukocytes, fibroblasts, or dried blood spots) and the identification of causative mutations in each allele of the TPP1/CLN2 gene. When it is not possible to perform both analyses, either demonstration of a) deficient TPP1 enzyme activity in leukocytes or fibroblasts, or b) detection of two pathogenic mutations in trans is diagnostic for CLN2 disease.

Congenital CLN disease in two siblings

BACKGROUND

Neuronal ceroid lipofuscinoses (NCL) is characterized by a combination of retinopathy, dementia, and epilepsy. As a group, they encompass ten distinct biological and clinical entities and are the most common type of childhood neurodegenerative disease.

PATIENTS AND METHODS

Case reports.

RESULTS

We demonstrate the clinical course of two neonates (brother and sister) with infantile neuronal ceroid lipofuscinoses (NCL) (CLN 10 disease) presenting with intractable seizures and respiratory insufficiency immediately after birth. Characteristic clinical, radiological and pathological findings of this form of NCL are presented.

CONCLUSIONS

We conclude that the diagnosis of CLN10 should be kept in mind as a differential diagnosis in newborns presenting with respiratory insufficiency and severe epilepsy that is largely refractory to anti-epileptic drugs (AED) treatment. Because of the severity of CLN10 disease and futility of treatment, important ethical issues arise when caring for children with this clinical entity.

Neuroimaging of lipid storage disorders

Lipid storage diseases, also known as the lipidoses, are a group of inherited metabolic disorders in which there is lipid accumulation in various cell types, including the central nervous system, because of the deficiency of a variety of enzymes. Over time, excessive storage can cause permanent cellular and tissue damage. The brain is particularly sensitive to lipid storage as the contents of the central nervous system must occupy uniform volume, and any increases in fluids or deposits will lead to pressure changes and interference with normal neurological function. In addition to primary lipid storage diseases, lysosomal storage diseases include the mucolipidoses (in which excessive amounts of lipids and carbohydrates are stored in the cells and tissues) and the mucopolysaccharidoses (in which abnormal glycosylated proteins cannot be broken down because of enzyme deficiency). Neurological dysfunction can be a manifestation of these conditions due to substrate deposition as well. This review will explore the modalities of neuroimaging that may have particular relevance to the study of the lipid storage disorder and their impact on elucidating aspects of brain function. First, the techniques will be reviewed. Next, the neuropathology of a few selected lipid storage disorders will be reviewed and the use of neuroimaging to define disease characteristics discussed in further detail. Examples of studies using these techniques will be discussed in the text.

Clinical, electrophysiological, imaging, and ultrastructural description in 68 patients with neuronal ceroid lipofuscinoses and its subtypes

PURPOSE

We evaluated the clinical, electrophysiological, imaging, and ultrastructural features of neuronal ceroid lipofuscinoses and its subtypes.

METHODS

The clinical, electrophysiological, imaging, histopathological, and ultrastructural features of 68 (age at onset: 4.3 ± 5.4 years) neuronal ceroid lipofuscinoses and its subtypes (infantile neuronal ceroid lipofuscinoses [9], late infantile neuronal ceroid lipofuscinoses [34], juvenile neuronal ceroid lipofuscinoses [23], and adult neuronal ceroid lipofuscinoses [2] were evaluated. Skin (n = 56), brain (n = 12), muscle (n = 4) and nerve (n = 1) biopsies confirmed the diagnosis.

RESULTS

Clinical manifestations were milestone regression (93%), involuntary movements (92%), seizures (89%), myoclonus (79%), and visual impairment (68%). Response to anticonvulsants was unsatisfactory. Electroencephalography (n = 59) was abnormal in 90%: background slowing (90%); epileptiform discharges (71%), and photoparoxysmal response (4/21). Visual-evoked (n = 33) and somatosensory evoked (n = 40) potentials were abnormal in 62% and 63% of patients. Cranial computed tomography (n = 33) showed diffuse cerebral (61%) and cerebellar (27%) atrophy. Magnetic resonance imaging was abnormal in all 43 patients who were scanned: diffuse atrophy (100%), cerebellar atrophy (40%), leukoencephalopathy (65%), and thalamic T2 W hypointensity (33%). Dermal inclusions such as curvilinear inclusions were the most common abnormality: late infantile neuronal ceroid lipofuscinoses (97%), juvenile neuronal ceroid lipofuscinoses (100%), and infantile neuronal ceroid lipofuscinoses (88%). Additional fingerprint inclusions were noted: juvenile neuronal ceroid lipofuscinoses (43%), late infantile neuronal ceroid lipofuscinoses (15%), and infantile neuronal ceroid lipofuscinoses (13%). Granular osmiophilic deposits were noted in 50% of infantile neuronal ceroid lipofuscinoses. In 75% of patients, there was good correlation between the clinical subtype and ultrastructural inclusion pattern. In 27% of neuronal ceroid lipofuscinoses, multiple inclusions were noted.

CONCLUSIONS

The diagnosis of neuronal ceroid lipofuscinoses should be considered in individuals with characteristic clinical presentations and characteristic ultrastructural dermal inclusions. Three fourths showed morphological correlation of the inclusions with neuronal ceroid lipofuscinoses subtype.

Metabolic causes of epileptic encephalopathy

Epileptic encephalopathy can be induced by inborn metabolic defects that may be rare individually but in aggregate represent a substantial clinical portion of child neurology. These may present with various epilepsy phenotypes including refractory neonatal seizures, early myoclonic encephalopathy, early infantile epileptic encephalopathy, infantile spasms, and generalized epilepsies which in particular include myoclonic seizures. There are varying degrees of treatability, but the outcome if untreated can often be catastrophic. The importance of early recognition cannot be overemphasized. This paper provides an overview of inborn metabolic errors associated with persistent brain disturbances due to highly active clinical or electrographic ictal activity. Selected diseases are organized by the defective molecule or mechanism and categorized as small molecule disorders (involving amino and organic acids, fatty acids, neurotransmitters, urea cycle, vitamers and cofactors, and mitochondria) and large molecule disorders (including lysosomal storage disorders, peroxisomal disorders, glycosylation disorders, and leukodystrophies). Details including key clinical features, salient electrophysiological and neuroradiological findings, biochemical findings, and treatment options are summarized for prominent disorders in each category.

Late infantile neuronal ceroid lipofuscinosis: mutations in the CLN2 gene and clinical course in Spanish patients

Late infantile neuronal ceroid lipofuscinosis (Jansky-Bielchowsky disease) is a rare disease caused by mutations in the CLN2 gene. The authors report the clinical outcome and correlate with genotype in 12 Spanish patients with this disease. Psychomotor regression, epilepsy, and other clinical symptoms/signs were assessed. Age at onset of clinical symptoms ranged from 18 months to 3.7 years, and they included delayed speech and simple febrile seizures followed by epilepsy. Partial seizures and myoclonic jerks occurred at an earlier age (median 3.4 and 3.7 years, respectively) than ataxia and cognitive decline (median 4 years). Clinical regression was initiated by loss of sentences (median 3.7 years) followed by loss of walking ability and absence of language (median 4.5 years). Patients showed blindness and lost sitting ability at similar age (median 5 years). The authors report 4 novel mutations in the CLN2 gene. This study provides detailed information about the natural history of this disease.

Cell biology and function of neuronal ceroid lipofuscinosis-related proteins

Neuronal ceroid lipofuscinoses (NCL) comprise a group of inherited lysosomal disorders with variable age of onset, characterized by lysosomal accumulation of autofluorescent ceroid lipopigments, neuroinflammation, photoreceptor- and neurodegeneration. Most of the NCL-related genes encode soluble and transmembrane proteins which localize to the endoplasmic reticulum or to the endosomal/lysosomal compartment and directly or indirectly regulate lysosomal function. Recently, exome sequencing led to the identification of four novel gene defects in NCL patients and a new NCL nomenclature currently comprising CLN1 through CLN14. Although the precise function of most of the NCL proteins remains elusive, comprehensive analyses of model organisms, particularly mouse models, provided new insight into pathogenic mechanisms of NCL diseases and roles of mutant NCL proteins in cellular/subcellular protein and lipid homeostasis, as well as their adaptive/compensatorial regulation at the transcriptional level. This review summarizes the current knowledge on the expression, function and regulation of NCL proteins and their impact on lysosomal integrity. This article is part of a Special Issue entitled: The Neuronal Ceroid Lipofuscinoses or Batten Disease.

Magnetic resonance imaging in neuronal ceroid lipofuscinosis and its subtypes

Studies on magnetic resonance imaging (MRI) observations in neuronal ceroid lipofuscinosis (NCL) are few and far between. We evaluated the MRI characteristics of patients with NCL and its subtypes. Forty-three out of 68 patients with ultrastructurally confirmed NCL (M:F=46:22; age at evaluation: 6.3±5.2 years) underwent brain MRI evaluation (1998-2010). The demography, phenotype and subtypes of NCL (n=43) [infantile (I-NCL): 5; late infantile (LI-NCL): 26; Juvenile (J-NCL): 11; adult (A-NCL): 1] were recorded. MRI (brain) was carried out using standard sequences in all. Brain atrophy and signal alterations were assessed visually. Brain MRI was abnormal in all 43 patients - diffuse cerebral atrophy (100%), cerebellar atrophy (40%), cerebral leucoencephalopathy (65%) and thalamic T2W-hypointensity (33%). Diffuse cerebral atrophy was noted in: I-NCL (100%), LI-NCL (62%), J-NCL (36%) and A-NCL (100%) [p=0.05]. Cerebellar atrophy was present in: LI-NCL (42%) and J-NCL (55%). Leucoencephalopathy was observed in: I- NCL (100%), LI-NCL (65%), J-NCL (45%) and A-NCL (100%)). Thalamic T2W-hypointensity was most frequent in I-NCL (80%) followed by J-NCL (36%) and LI-NCL (23%). This is the largest study of its kind. The presence of cerebellar/cerebral atrophy, leucoencephalopathy and thalamic T2W-hypointensity in an appropriate clinical setting might provide clues to the diagnosis of NCL: leucoencephalopathy and thalamic hypointensity (T2W) were noted more frequently in I-NCL, periventricular and parieto-occipital hyperintensities in LI-NCL, and cerebellar atrophy in J-NCL.

Clinical study in Chinese patients with late-infantile form neuronal ceroid lipofuscinoses

Clinical findings, pathological features and tripeptidyl peptidase 1 (TPP1) activity and genetic mutation analysis data of nine patients affected with the late-infantile form of neuronal ceroid lipofuscinoses (LINCL) in China are systematically reviewed with long-term follow-up. The patients were enrolled if curvilinear bodies were found on lymphocyte, skin or muscle specimens' examination, and/or reduction of tripeptidyl peptidase 1 (TPP1) activity were detected. CLN2 gene mutation were tested in five patients. The patients have onset age of 2-3.5 years, and most of them initially present partial seizure, and then progressed to deteriorated mental function, refractory myoclonic seizures, impaired vision, and ataxia with cerebellar atrophy. Discrete small vacuolated lymphocytes are found in 5-10% lymphocytes in 5 patients examined. Curvilinear bodies were found in vacuolated lymphocytes, in skin and muscle tissues. Tripeptidyl peptidase 1 (TPP1) activities are reduced in 5 patients with different CLN2 gene mutation. Detection of vacuolated lymphocytes may be a screen method for LINCL, ultrastructural examination of lymphocytes, combined with TPP1 activity assay, allowing for a definite and faster diagnosis and classification with minimal invasion.

Novel neuroimaging finding in palmitoyl protein thioesterase-1-related neuronal ceroid lipofuscinosis

Palmitoyl protein thioesterase-1 (PPT1)-related neuronal ceroid lipofuscinosis is a type of neuronal ceroid lipofuscinosis caused by a deficiency of the enzyme palmitoyl protein thioesterase-1. Cranial magnetic resonance imaging reveals more severe atrophy in the cerebral hemispheres than in the cerebellum. The basal ganglia and particularly the thalamus demonstrate low signal intensity on T(2)-weighted images from an early age. We present three patients with PPT1-related neuronal ceroid lipofuscinosis who exhibited isolated, symmetric signal changes in the bilateral dentate nucleus as sole early neuroimaging abnormality. Neither cerebral or cerebellar atrophy nor signal changes in the thalamus/basal ganglia were evident. This neuroimaging finding in PPT1-related neuronal ceroid lipofuscinosis was not previously reported.

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.

Juvenile neuronal ceroid lipofuscinosis: clinical course and genetic studies in Spanish patients

BACKGROUND

Juvenile neuronal ceroid lipofuscinosis (JNCL, NCL3, Batten disease) is usually caused by a 1.02-kb deletion in the CLN3 gene. Mutations in the CLN1 gene may be associated with a variant form of JNCL (vJNCL). We report the clinical course and molecular studies in 24 patients with JNCL collected from 1975 to 2010 with the aim of assessing the natural history of the disorder and phenotype/genotype correlations.

PATIENTS AND METHODS

Patients were classified into the groups of vJNCL with mutations in the CLN1 gene and/or granular osmiophilic deposit (GROD) inclusion bodies (n = 11) and classic JNCL (cJNCL) with mutations in the CLN3 gene and/or fingerprint (FP) profiles (n = 13). Psychomotor impairment included regression of acquired skills, cognitive decline, and clinical manifestations of the disease. We used Kaplan-Meier analyses to estimate the age of onset of psychomotor impairment.

RESULTS

Patients with vJNCL showed learning delay at an earlier age (median 4 years, 95% confidence interval [CI] 3.1-4.8) than those in the cJNCL group (median 8 years, 95% CI 6.2-9.7) (P = 0.001) and regression of acquired skills at a younger age. Patients with vJNCL showed a more severe and progressive clinical course than those with cJNCL. There may be a Gypsy ancestry for V181L missense mutation in the CLN1 gene.

CONCLUSIONS

The rate of disease progression may be useful to diagnose vJNCL or cJNCL, which should be confirmed by molecular studies in CLN1/CLN3 genes. Further studies of genotype/phenotype correlation will be helpful for understanding the pathogenesis of this disease.

Neuroimaging of inherited metabolic disorders producing seizures

Both MRI with FLAIR and T2, diffusion and post-contrast T1 imaging, as well as proton MRS, allow for defining an approach to evaluating MRI and MRS in neurometabolic diseases producing seizures. Examples of this approach are given here in a limited number of cases, recognizing that a more comprehensive review is beyond the scope of this paper.

Psychiatric and behavioral manifestations of lysosomal storage disorders

The different lysosomal storage disorders (LSDs) manifest with a wide spectrum of clinical presentations. Most of these disorders are typically diagnosed early in life, due to the severity of the associated phenotypes. However, it is important to appreciate that some of the LSDs present later in adolescence or adulthood. The diverse findings triggering the initial diagnosis, as well as the range of manifestations arising later during the disease course, contribute to the complexity of these issues. Clinical presentations occurring at a more advanced age, especially psychiatric and behavioral manifestations, can be overlooked or misdiagnosed. This review describes different psychiatric and behavioral manifestations encountered in individuals with LSDs, including psychosis, schizophrenia, mood disorders, aggressiveness, early-onset dementia, and conduct disorder. Twelve different disorders are presented, including descriptions of their associated biochemical abnormalities, clinical presentations, pathology, epidemiology, and genetics. In addition, discussions of neurocognitive, behavioral, and psychiatric findings are outlined for each disorder. A greater awareness of these features may help to reduce missed diagnoses, to avoid unnecessary, invasive and expensive testing, and to facilitate an earlier detection of these rare disorders. Earlier diagnosis can enable the implementation of appropriate interventions and improve genetic counseling.

A 30-year follow-up of a neuronal ceroid lipofuscinosis patient with mutations in CLN3 and protracted disease course

Reported here is the 30-year follow-up of a patient, diagnosed with juvenile neuronal ceroid lipofuscinosis, who was compound heterozygous for the common 1-kb deletion and the missense mutation p.Glu295Lys in the CLN3 gene. Visual failure was noticed at 6 years of age, but thereafter disease progression was atypical. Polyneuropathy and cerebellar signs were observed after age 20, and epilepsy and slight mental decline after age 35. From then on, there was rapid deterioration, and the patient died at age 39. This case highlights the importance of exact genotyping for disease course prediction and management.

JNCL patients show marked brain volume alterations on longitudinal MRI in adolescence

Juvenile neuronal ceroid lipofuscinosis (JNCL, CLN3) is an inherited lysosomal disease. We used longitudinal MRI, for the first time, to evaluate the rate of brain volume alterations in JNCL. Six patients (mean ages of 12.4 years and 17.3 years) and 12 healthy controls were studied twice with 1.5 T MRI. White matter (WM), gray matter (GM) and CSF volumes were measured from the sets of T1-weighted 3-dimensional MR images using a fully automated image-processing procedure. The brain volume alterations were calculated as percentage change per year. The GM and whole brain volumes decreased and the CSF volume increased significantly more in the patients than in controls (p-values for the null hypothesis of equal means were 0.001, 0.004, and 0.005, respectively). We found no difference in the WM volume change between the populations. In patients, the GM volume decreased 2.4 % (SD 0.5 %, p 0.0001 for the null hypothesis of zero mean change between observations), the whole brain volume decreased 1.1 % (SD 0.5 %, p = 0.003), and the CSF volume increased 2.7 % (SD 1.8 %, p = 0.01) per year. In normal controls, only the mean white matter volume was significantly altered (0.8 % increase, SD 0.7 %, and p = 0.001).

CONCLUSION

We demonstrated by longitudinal MRI that the annual rate of the gray matter loss in adolescent JNCL patients is as high as 2.4 %.

In vivo MRI reveals the dynamics of pathological changes in the brains of cathepsin D-deficient mice and correlates changes in manganese-enhanced MRI with microglial activation

Cathepsin D (CTSD; EC 3.4.23.5) is essential for normal development and/or maintenance of neurons in the central nervous system: its deficiency causes a devastating neurological disorder with severely shortened life span in man, sheep and mouse. Neuropathologically, the CTSD deficiencies are characterized by selective neuronal degeneration, gliosis and accumulation of autofluorescent proteinaceous storage material in neurons. Our aim was to study the dynamics behind the pathological alterations occurring in the brains of CTSD-deficient (CTSD-/-) mice by using in vivo magnetic resonance imaging (MRI) and histology. In order to do this, we measured T(2) signal intensity (SI), apparent diffusion coefficient, area and volume of multiple brain structures from MR images acquired using T(2)-, T(1)- and diffusion-weighted sequences at three time points during disease progression. MRI revealed no differences in the brains between CTSD-/- and control mice at postnatal day 15+/-1 (P15+/-1), representing an initial stage of the disease. In the intermediate stage of the disease, P19(+/-1), SI alterations in the thalami of the affected mice became evident in both T(1)- and T(2)-weighted images. The terminal stage of the disease, P25, was characterized by marked alterations in the T(2) SI, apparent diffusion coefficient and volume of multiple brain structures in CTSD-/- mice. In addition, manganese enhanced high-resolution T(1)-weighted 3D sequences (MEMRI) and histological stainings revealed that the hyperintense signal areas in MEMRI matched perfectly with areas of microglial activation in the brains of CTSD-/- mice at the terminal disease stage. In conclusion, the SI alterations in the thalami of CTSD-/- mice preceded other changes, and the degenerative process was greatly enhanced at the age P19(+/-1), leading to severely reduced brain volume in just 6 days.

Assessing disease severity in late infantile neuronal ceroid lipofuscinosis using quantitative MR diffusion-weighted imaging

BACKGROUND AND PURPOSE

Late infantile neuronal ceroid lipofuscinosis (LINCL), a form of Batten disease, is a fatal neurodegenerative genetic disorder, diagnosed via DNA testing, that affects approximately 200 children in the United States at any one time. This study was conducted to evaluate whether quantitative data derived by diffusion-weighted MR imaging (DWI) techniques can supplement clinical disability scale information to provide a quantitative estimate of neurodegeneration, as well as disease progression and severity.

MATERIALS AND METHODS

This study prospectively analyzed 32 DWI examinations from 18 patients having confirmed LINCL at various stages of disease. A whole-brain apparent diffusion coefficient (ADC) histogram was fitted with a dual Gaussian function combined with a function designed to model voxels containing a partial volume fraction of brain parenchyma versus CSF. Previously published whole-brain ADC values of age-matched control subjects were compared with those of the LINCL patients. Correlations were tested between the peak ADC of the fitted histogram and patient age, disease severity, and a CNS disability scale adapted for LINCL.

RESULTS

ADC values assigned to brain parenchyma were higher than published ADC values for age-matched control subjects. ADC values between patients and control subjects began to differ at 5 years of age based on 95% confidence intervals. ADC values had a nearly equal correlation with patient age (R2=0.71) and disease duration (R2=0.68), whereas the correlation with the central nervous system disability scale (R2=0.27) was much weaker.

CONCLUSION

This study indicates that brain ADC values acquired using DWI may be used as an independent measure of disease severity and duration in LINCL.

Thalami and corona radiata in juvenile NCL (CLN3): a voxel-based morphometric study

Juvenile neuronal ceroid lipofuscinosis (CLN3) is characterized by progressive cerebral atrophy. The purpose of this study was to re-evaluate the three-dimensional magnetic resonance (3D-MR) images of patients with CLN3 using voxel-based morphometry (VBM) to achieve a detailed understanding of the affected brain regions. T1-weighted 3D-MR images of 15 patients with CLN3 (age range: 12-25 years, mean age 17.6 years) and 15 age- and sex-matched controls were analyzed using VBM. VBM showed strikingly focal alterations in the brains of CLN3 patients: the gray matter volume was significantly decreased in the dorsomedial part of the thalami of CLN3 patients. In addition, the volume of the white matter was significantly decreased in the corona radiata, containing cortical efferents and afferents in the transition between the internal capsule and the subcortical white matter. These data suggest that the dorsomedial part of the thalamus and the corona radiata may have a central, previously unrecognized role in the pathogenesis of CLN3.

Topology and endoplasmic reticulum retention signals of the lysosomal storage disease-related membrane protein CLN6

CLN6 is a polytopic membrane protein of unknown function resident in the endoplasmic reticulum (ER). Mutant CLN6 causes the lysosomal storage disorder neuronal ceroid lipofuscinosis. Defining the topology of CLN6, and the structural domains and motifs required for interaction with cytosolic and luminal proteins may allow insights into its function. In this study we analysed the topology, ER retention and oligomerization of CLN6. We demonstrated, by differential membrane permeabilization of transfected BHK cells using specific detergents and two distinct antibodies, that CLN6 contains an N-terminal cytoplasmic domain, seven transmembrane domains, and a luminal C terminus. Mutational analyses and confocal immunofluorescence microscopy showed that changes of potential ER localization signals in the N- or C-terminal domain (a triple arginine cluster, and a dileucine motif) did not alter the subcellular localization of CLN6. The deletion of a dilysine motif impaired partially the ER localization of CLN6. Furthermore, expression analyses of fusion and deletion constructs in non-neuronal and neuronal cells suggested that two portions of CLN6 contributed to its retention within the ER. We showed that the N-terminal domain was necessary but not sufficient for ER retention of CLN6 and that deletion of transmembrane domains 6 and 7 was accompanied with the loss of ER localization and, in some instances, trafficking to the cisGolgi. From these data we concluded that CLN6 maintains its ER localization by expressing retention signals present in both the N-terminal cytosolic domain and in the carboxy-proximal transmembrane domains 6 and 7. Additionally, the ability of CLN6 to homodimerize may also prevent exit from the ER via an interaction with membrane-associated factors.

Neuronal ceroid lipofuscinosis: a common pathway?

The neuronal ceroid lipofuscinoses are pediatric neurodegenerative diseases with common clinical features. Of the nine clinical variants (CLN1-CLN9), six have been genetically identified. Most variants manifest cell death and dysregulated sphingolipid metabolism, suggesting the proteins defective in these disorders may interact along one pathway. NCL patient-derived cell lines exhibit cell growth and apoptotic defects that reverse following transfection with the wild-type gene. The membrane-bound proteins CLN3, CLN6, and CLN8 complement each other, as do CLN1 and CLN2 proteins, with respect to growth and apoptosis. The CLN2 protein also corrects growth and apoptosis in CLN3-, CLN6-, and CLN8-deficient cell lines. Neither CLN1-deficient nor CLN2-deficient growth defects are corrected by CLN3, CLN6, and CLN8 proteins. CLN2, CLN3, CLN6, and CLN8 proteins co-immunoprecipitate and co-localize to early and/or recycling endosomes and lipid rafts. Additionally, CLN2p and CLN1p co-immunoprecipitate. The work presented supports interactions between NCL proteins occurring at multiple points along one pathway.

Diagnosis of the neuronal ceroid lipofuscinoses: An update

For the majority of families affected by one of the neuronal ceroid lipofuscinoses (NCLs), a biochemical and/or genetic diagnosis can be achieved. In an individual case this information not only increases understanding of the condition but also may influence treatment choices and options. The presenting clinical features prompt initial investigation and also guide clinical care. The clinical labels "infantile NCL", "late infantile NCL" and "juvenile NCL", therefore remain useful in practice. In unusual or atypical cases ultra-structural analysis of white blood cells or other tissue samples enables planning and prioritisation of biochemical and genetic tests. This review describes current methods available to achieve clinical, pathological, biochemical and genetic diagnosis in children presenting with symptoms suggestive of one of the NCLs.

Blood film examination for vacuolated lymphocytes in the diagnosis of metabolic disorders; retrospective experience of more than 2,500 cases from a single centre

BACKGROUND

A range of metabolic diseases can result in abnormal accumulation of metabolic byproducts, resulting in abnormal lymphocyte cytoplasmic vacuolation, identifiable on routine blood film examination.

AIMS

This study retrospectively examines the usefulness of blood film examination for vacuolated lymphocytes in a specialist paediatric pathology department in relation to patient's age and presentation. It also describes specific diagnostic features in relation to specific classes of metabolic disease.

METHODS

Retrospective review of a histopathology database to identify all blood films examined for the detection of vacuolated lymphocytes during a 15 year period (1989-2004).

RESULTS

In total, 2,550 blood films were investigated. The median age at submission was 2 years (range, birth to 88), and>90% of samples were from children<18 years. The most common indications were developmental delay/regression, ataxia, seizures, and cardiomyopathy. Vacuolated lymphocytes were identified in 156 films (6.1%). The frequency of vacuolated lymphocytes varied with clinical presentation, with ophthalmic indications having the highest positive rate (40%). In cases with vacuolated lymphocytes, a wide range of underlying metabolic diagnoses was apparent, the most common being juvenile neuronal ceroid lipofuscinosis and acid maltase deficiency, which accounted for more than half of the diagnoses.

CONCLUSIONS

The examination of blood films for lymphocyte vacuolation is clinically useful in patients with a history suggestive of metabolic disease. The test is cheap, rapid, minimally invasive, and provides first line screening, with some findings indicating clues to a specific underlying diagnosis.

The Finnish Disease Heritage III: the individual diseases

This article is the third and last in a series entitled The Finnish Disease Heritage I-III. All the 36 rare hereditary diseases belonging to this entity are described for clinical and molecular genetic purposes, based on the Finnish experience gathered over a period of half a century. In addition, five other diseases are mentioned. They may be included in the list of the "Finnish diseases" after adequate complementary studies.