Serial MRI findings in the Costa Rican variant of neuronal ceroid-lipofuscinosis

Neuronal ceroid lipofuscinosis in the South American-Caribbean region: An epidemiological overview

Neuronal ceroid lipofuscinoses (NCLs) comprise 13 hereditary neurodegenerative pathologies of very low frequency that affect individuals of all ages around the world. All NCLs share a set of symptoms that are similar to other diseases. The exhaustive collection of data from diverse sources (clinical, genetic, neurology, ophthalmology, etc.) would allow being able in the future to define this group with greater precision for a more efficient diagnostic and therapeutic approach. Despite the large amount of information worldwide, a detailed study of the characteristics of the NCLs in South America and the Caribbean region (SA&C) has not yet been done. Here, we aim to present and analyse the multidisciplinary evidence from all the SA&C with qualitative weighting and biostatistical evaluation of the casuistry. Seventy-one publications from seven countries were reviewed, and data from 261 individuals (including 44 individuals from the Cordoba cohort) were collected. Each NCL disease, as well as phenotypical and genetic data were described and discussed in the whole group. The CLN2, CLN6, and CLN3 disorders are the most frequent in the region. Eighty-seven percent of the individuals were 10 years old or less at the onset of symptoms. Seizures were the most common symptom, both at onset (51%) and throughout the disease course, followed by language (16%), motor (15%), and visual impairments (11%). Although symptoms were similar in all NCLs, some chronological differences could be observed. Sixty DNA variants were described, ranging from single nucleotide variants to large chromosomal deletions. The diagnostic odyssey was probably substantially decreased after medical education activities promoted by the pharmaceutical industry and parent organizations in some SA&C countries. There is a statistical deviation in the data probably due to the approval of the enzyme replacement therapy for CLN2 disease, which has led to a greater interest among the medical community for the early description of this pathology. As a general conclusion, it became clear in this work that the combined bibliographical/retrospective evaluation approach allowed a general overview of the multidisciplinary components and the epidemiological tendencies of NCLs in the SA&C region.

Neuronal Ceroid Lipofuscinosis: The Multifaceted Approach to the Clinical Issues, an Overview

The main aim of this review is to summarize the current state-of-art in the field of childhood Neuronal Ceroid Lipofuscinosis (NCL), a group of rare neurodegenerative disorders. These are genetic diseases associated with the formation of toxic endo-lysosomal storage. Following a brief historical review of the evolution of NCL definition, a clinically-oriented approach is used describing how the early symptoms and signs affecting motor, visual, cognitive domains, and including seizures, may lead clinicians to a rapid molecular diagnosis, avoiding the long diagnostic odyssey commonly observed. We go on to focus on recent advances in NCL research and summarize contributions to knowledge of the pathogenic mechanisms underlying NCL. We describe the large variety of experimental models which have aided this research, as well as the most recent technological developments which have shed light on the main mechanisms involved in the cellular pathology, such as apoptosis and autophagy. The search for innovative therapies is described. Translation of experimental data into therapeutic approaches is being established for several of the NCLs, and one drug is now commercially available. Lastly, we show the importance of palliative care and symptomatic treatments which are still the main therapeutic interventions.

Neurometabolic Diseases in Children: Magnetic Resonance Imaging and Magnetic Resonance Spectroscopy Features

BACKGROUND

Neurometabolic diseases are a group of diseases secondary to disorders in different metabolic pathways, which lead to white and/or gray matter of the brain involvement.

DISCUSSION

Neurometabolic disorders are divided in two groups as dysmyelinating and demyelinating diseases. Because of wide spectrum of these disorders, there are many different classifications of neurometabolic diseases. We used the classification according to brain involvement areas. In radiological evaluation, MRI provides useful information for these disseases.

CONCLUSION

Magnetic Resonance Spectroscopy (MRS) provides additional metabolic information for diagnosis and follow ups in childhood with neurometabolic diseases.

A first CLN6 variant case of late infantile neuronal ceroid lipofuscinosis caused by a homozygous mutation in a boy from China: a case report

Background

Neuronal ceroid lipofuscinosis (NCLs) are lysosomal storage disorders characterized by seizures, motor impairment, and loss of vision. Ceroid lipofuscinosis (CLN) gene mutations are the cause, but NCL cases arising from CLN6 mutations have not been described in China to date. The CLN6 protein, which plays a role in lysosomal function, is an endoplasmic reticulum (ER) membrane protein with seven transmembrane (TM) domains. It has a cytosolic-facing amino terminal domain and a luminal-facing carboxyl terminal domain, with six loops between the TM domains.

Case presentation

Here we report a case involving a Chinese boy whose suspected diagnosis was a hereditary leukoencephalopathy, based on brain MRI imaging and epilepsy symptoms, language articulation disorders, ataxia, and unstable gait. The electroencephalogram showed epileptic discharges, and the brain MRI scan showed high signal intensity adjacent to the bilateral posterior horns of the lateral ventricles on T2-weighted images, along with cerebellar atrophy. Using next-generation sequencing for the genes in a panel for hereditary leukoencephalopathies, we detected a homozygous missense point mutation c.892G > A(p.Glu298Lys) in CLN6, and the variant was interpreted as pathogenic on in silico analysis. Absence of this mutation was confirmed in 259 controls. Late infantile NCL and secondary epilepsy were diagnosed, and oral sodium valproate was prescribed. The epilepsy was not well controlled, however, and the other signs had not improved at the 6-month follow-up. We also analyzed the loci of 31 CLN6 missense mutations, including those previously reported and the current one. We found that 22.6% (7/31) of the mutations are in the cytoplasmic domains, about 32.2% (10/31) are in the TM domains, and about 45.2% (14/31) are in the luminal domains. These mutations were mostly located in the TM3-TM4 loop (6/31), TM1-TM2 loop (4/31), and C-terminus (4/31), with none found in the TM4-TM5 loop, TM5-TM6 loop, or TM7.

Conclusions

We report the first case in China of NCL caused by a CLN6 mutation, expanding the genotype options for NCLs. In practice, NCLs generally are not the initial suspected diagnosis for such cases. Use of a gene sequencing panel for investigating unexplained seizures or leukoencephalopathies can help confirm the diagnosis.

Electronic supplementary material

The online version of this article (10.1186/s12881-018-0690-x) contains supplementary material, which is available to authorized users.

First Japanese variant of late infantile neuronal ceroid lipofuscinosis caused by novel CLN6 mutations

The clinical phenotypes of neuronal ceroid lipofuscinoses (NCLs) have been determined based on the age of onset and clinical symptoms. NCLs with onset between age 2 and 4years are known as late infantile neuronal ceroid lipofuscinoses (LINCLs). The clinical features of LINCLs include visual loss and progressive myoclonus epilepsy (PME) characterized by myoclonus, seizures, ataxia, and both mental and motor deterioration. There have been reports of several genes associated with LINCLs, with mutations in the CLN6 gene reported to cause variant forms of LINCLs (vLINCLs). Here, we report the first Japanese vLINCL caused by novel CLN6 mutations, found in a patient diagnosed by whole-exome sequencing. Visual acuity in our patient was preserved until the early teens. It remains to be elucidated if preserved visual function is related to the novel mutations of CLN6. Our case reveals the efficacy of whole-exome sequencing for examination of PMEs and highlights the existence of the CLN6 mutation in the Japanese population.

Correlation Among Genotype, Phenotype, and Histology in Neuronal Ceroid Lipofuscinoses: An Individual Patient Data Meta-Analysis

BACKGROUND

Neuronal ceroid lipofuscinoses (NCL) are heterogeneous neurodegenerative disorders. A better understanding of genotype-phenotype-histology correlation is expected to improve patient care and enhance understanding for phenotypic variability. This meta-analysis studies the correlation of NCL genotypes with clinical phenotypes, ages of onset, and pathologic findings.

METHODS

A structured MEDLINE search was performed using search strings incorporating relevant Medical Subject Headings (MeSH) terms. Studies of NCL patients with genetic, clinical, and histologic data were included. Individual patient data were extracted. Chi-square statistic was used to test the genotype differences in clinical phenotypes and histology. The distribution of age(s) of onset as a function of genotype was explored. Pairwise comparisons were performed with robust analysis of variance.

RESULTS

Sixty-eight studies including a total of 440 individuals with NCL were analyzed. Genetic testing was performed on 395 patients, and a pathologic mutation was identified in 372 of 395 of them. A significant clustering of genotypes into juvenile-onset (only CLN3) and infantile-onset (all others) phenotypes was observed (P < 0.0001). However, the CLN6 genotype showed a bimodal onset and included 14 of 17 subjects with the adult-onset phenotype. The estimated age of onset was respectively lower for subjects with CLN1 mutation (3.01 years, 95% confidence interval [CI] = 2.54 to 3.49) and higher for those with CLN6 mutation (16.33 years, 95% CI = 15.68 to 16.98), compared with other genotypes (P < 0.05 for pairwise comparisons). There was a significant (P < 0.0001) clustering of genotype observed according to the sampled tissue types and electron microscopic findings.

CONCLUSIONS

NCL genotypes significantly differ in terms of ages of onset and clinical phenotypes. There is a distinct segregation of genotypes and electron microscopic findings and high-yield tissue types for pathologic study. This information can possibly facilitate testing and diagnosis in resource-limited settings.

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.

Location and connectivity determine GABAergic interneuron survival in the brains of South Hampshire sheep with CLN6 neuronal ceroid lipofuscinosis

The neuronal ceroid lipofuscinoses (NCLs, Batten disease) are fatal inherited neurodegenerative diseases. Sheep affected with the CLN6 form provide a valuable model to investigate underlying disease mechanisms from preclinical stages. Excitatory neuron loss in these sheep is markedly regional, localized early reactive changes accurately predicting neuron loss and subsequent symptom development. This investigation of GABAergic interneuron loss revealed similar regional effects that correlate with symptoms. Loss of parvalbumin positive neurons from the affected cortex was apparent at four months and became profound by 19 months, as was somatostatin positive neuron loss to a lesser extent. Conversely calbindin and neuropeptide Y positive neurons were relatively preserved and calretinin staining temporarily increased. Staining of subcortical regions was more intense but subcortical architecture remained relatively intact. Discrete subcortical changes followed from cortical changes in interconnected regions. These data highlight cellular location and interconnectivity as the major determinants of neuron survival, rather than phenotype.

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.

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.