Long-term outcome of a cohort of Italian patients affected with alpha-Mannosidosis

Alpha-mannosidosis (MIM #248500) is an ultra-rare autosomal recessive lysosomal storage disease with multi-system involvement and a wide phenotypic spectrum. Information on long-term outcomes remains poor. We present the long-term outcomes (median, 19 years) of nine patients with alpha-mannosidosis, three females and six males, followed at a single center. The findings of the nine patients were collected from medical records and reported as mean ± SD or median, and range. The age of onset of the first symptoms ranged from 0-1 to 10 years. The diagnostic delay ranged from 2 to 22 years (median= 11 years). Coarse face, hearing, heart valves, joints, gait, language, dysarthria, psychiatric symptoms, I.Q., MRI, walking disabilities, orthopedic disturbances and surgeries showed a slow worsening over the decades. Our patients showed a slowly worsening progressive outcome over the decades. Psychiatric symptoms were present in 100% of our population and improved with the appropriate pharmacological intervention. This aspect requires attention when following up on these patients. Our description of the long-term evolution of alpha-mannosidosis patients may provide basic knowledge for understanding the effects of specific treatments.

Integrative human and murine multi-omics: Highlighting shared biomarkers in the neuronal ceroid lipofuscinoses

Neuronal ceroid lipofuscinosis (NCL) is a group of neurodegenerative disorders whose molecular mechanisms remain largely unknown. Omics approaches are among the methods that generate new information on modifying factors and molecular signatures. Moreover, omics data integration can address the need to progressively expand knowledge around the disease and pinpoint specific proteins to promote as candidate biomarkers. In this work, we integrated a total of 62 proteomic and transcriptomic datasets originating from humans and mice, employing a new approach able to define dysregulated processes across species, stages and NCL forms. Moreover, we selected a pool of differentially expressed proteins and genes as species- and form-related biomarkers of disease status/progression and evaluated local and spatial differences in most affected brain regions. Our results offer promising targets for potential new therapeutic strategies and reinforce the hypothesis of a connection between NCLs and other forms of dementia, particularly Alzheimer's disease.

Risk of psychosis in autism spectrum disorder individuals exposed to psychosocial stressors: A 9-year chart review study

Psychosocial stressors have been suggested to precipitate psychotic episodes in patients with pre-existing psychosis and otherwise healthy subjects. However, such a risk has never been formally investigated in individuals with autism spectrum disorder (ASD). Sixty-nine autistic adolescents hospitalized for psychotic/manic symptoms (PSY) and other mental health issues (NPSY) over a 9-year period were compared with reference to their previous exposure to psychosocial stressors. ASD diagnoses satisfied the International Classification of Diseases (ICD)-10 criteria. Psychotic/manic symptom assessment followed the Kiddie Schedule for Affective Disorders and Schizophrenia (K-SADS). Psychosocial stressor exposure was collected separately at each admission. Preliminarily, univariate between-group comparisons were conducted. Then, a binomial model was adopted to investigate associations with previous exposure to psychosocial stressors. Results were reported with a change in AIC (ΔAIC). PSY patients presented with higher previous exposure to adverse life events (30.43% vs. 6.52%, OR = 6.079 [1.209, 40.926], p = 0.013) and school/work difficulties (30.43% vs. 8.70%, OR = 4.478 [0.984, 23.846], p = 0.034) than NPSY ones. Admissions for psychotic/manic symptoms occurred more likely in the context of family disturbances (OR = 2.275 [1.045, 5.045], p = 0.030) and adverse life events (OR = 3.489 [1.194, 11.161], p = 0.014). The fitted binomial model was found to be significant compared to the random effects model (ΔAIC = -1.962; χ2 10  = 21.96, p = 0.015), with the risk of presenting psychotic/manic symptoms being increased by family disturbances (z = +4.118) and school/work difficulties (z = +2.455). The results suggest a potential psychosis-inducing effect of psychosocial stressors in ASD, which has clinical and policy implications.

Enhanced expression of the autophagosomal marker LC3-II in detergent-resistant protein lysates from a CLN3 patient's post-mortem brain

• Neuronal Ceroido Lipofuscinoses (NCL) are inherited, neurodegenerative disorders associated with lysosomal storage. • Impaired autophagy plays a pathogenetic role in several NCL forms, including CLN3 disease, but study on human brains lacks. • In post-mortem brain samples of a CLN3 patient the LC3-I to LC3-II shift was consistent with activated autophagy. However, the autophagic process seemed to be ineffective due to the presence of lysosomal storage markers. • After fractionation with buffers of increasing detergent-denaturing strength, a peculiar solubility pattern of LC3-II was observed in CLN3 patient's samples, suggesting a different lipid composition of the membranes where LC3-II is stacked.

Phenotypic Spectrum and Molecular Findings in 17 ATR-X Syndrome Italian Patients: Some New Insights

ATR-X syndrome is a rare X-linked congenital disorder caused by hypomorphic mutations in the ATRX gene. A typical phenotype is well defined, with cognitive impairment, characteristic facial dysmorphism, hypotonia, gastrointestinal, skeletal, urogenital, and hematological anomalies as characteristic features. With a few notable exceptions, general phenotypic differences related to specific ATRX protein domains are not well established and should not be used, at least at the present time, for prognostic purposes. The phenotypic spectrum and genotypic correlations are gradually broadening, mainly due to rapidly increasing accessibility to NGS. In this scenario, it is important to continue describing new patients, illustrating the mode and age of onset of the typical and non-typical features, the classical ones and those tentatively added more recently. This report of well-characterized and mostly unreported patients expands the ATR-X clinical spectrum and emphasizes the importance of better clinical delineation of the condition. We compare our findings to those of the largest ATR-X series reported so far, discussing possible explanations for the different drawn conclusions.

Integrative Organelle-Based Functional Proteomics: In Silico Prediction of Impaired Functional Annotations in SACS KO Cell Model

Autosomal recessive spastic ataxia of Charlevoix-Saguenay (ARSACS) is an inherited neurodegenerative disease characterized by early-onset spasticity in the lower limbs, axonal-demyelinating sensorimotor peripheral neuropathy, and cerebellar ataxia. Our understanding of ARSACS (genetic basis, protein function, and disease mechanisms) remains partial. The integrative use of organelle-based quantitative proteomics and whole-genome analysis proposed in the present study allowed identifying the affected disease-specific pathways, upstream regulators, and biological functions related to ARSACS, which exemplify a rationale for the development of improved early diagnostic strategies and alternative treatment options in this rare condition that currently lacks a cure. Our integrated results strengthen the evidence for disease-specific defects related to bioenergetics and protein quality control systems and reinforce the role of dysregulated cytoskeletal organization in the pathogenesis of ARSACS.

Lysosomal Proteomics Links Disturbances in Lipid Homeostasis and Sphingolipid Metabolism to CLN5 Disease

CLN5 disease (MIM: 256731) represents a rare late-infantile form of neuronal ceroid lipofuscinosis (NCL), caused by mutations in the CLN5 gene that encodes the CLN5 protein (CLN5p), whose physiological roles stay unanswered. No cure is currently available for CLN5 patients and the opportunities for therapies are lagging. The role of lysosomes in the neuro-pathophysiology of CLN5 disease represents an important topic since lysosomal proteins are directly involved in the primary mechanisms of neuronal injury occurring in various NCL forms. We developed and implemented a lysosome-focused, label-free quantitative proteomics approach, followed by functional validations in both CLN5-knockout neuronal-like cell lines and Cln5-/- mice, to unravel affected pathways and modifying factors involved in this disease scenario. Our results revealed a key role of CLN5p in lipid homeostasis and sphingolipid metabolism and highlighted mutual NCL biomarkers scored with high lysosomal confidence. A newly generated cln5 knockdown zebrafish model recapitulated most of the pathological features seen in NCL disease. To translate the findings from in-vitro and preclinical models to patients, we evaluated whether two FDA-approved drugs promoting autophagy via TFEB activation or inhibition of the glucosylceramide synthase could modulate in-vitro ROS and lipid overproduction, as well as alter the locomotor phenotype in zebrafish. In summary, our data advance the general understanding of disease mechanisms and modifying factors in CLN5 disease, which are recurring in other NCL forms, also stimulating new pharmacological treatments.

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.

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.

Migrating Focal Seizures and Myoclonic Status in ARV1-Related Encephalopathy

Objective

To report longitudinal clinical, EEG, and MRI findings in 2 sisters carrying compound heterozygous ARV1 mutations and exhibiting a peculiar form of developmental and epileptic encephalopathy (DEE). Neuropathologic features are also described in one of the sisters.

Methods

Clinical course description, video-EEG polygraphic recordings, brain MRI, skin and muscle biopsies, whole-exome sequencing (WES), and brain neuropathology.

Results

Since their first months of life, both girls exhibited severe axial hypotonia, visual inattention, dyskinetic movements, severe developmental delay, and slow background EEG activity. Intractable nonmotor seizures started in both at the eighth month of life, exhibiting the electroclinical characteristics of epilepsy of infancy with migrating focal seizures (EIMFS). In the second year of life, continuous epileptiform EEG activity of extremely high amplitude appeared in association with myoclonic status, leading to severely impaired alertness and responsiveness. Repeated brain MRI revealed progressive atrophic changes and severe hypomyelination. WES identified a compound heterozygous in the ARV1 gene [(p.Ser122Glnfs*7) and (p.Trp163*)] in one patient and was subsequently confirmed in the other. Both sisters died prematurely during respiratory infections. Postmortem neuropathologic examination of the brain, performed in one, revealed atrophic brain changes, mainly involving the cerebellum.

Conclusions

This report confirms that biallelic ARV1 mutations cause a severe form of DEE and adds epilepsy with migrating focal seizures and myoclonic status to the spectrum of epilepsy phenotypes. Considering the potential role of human ARV1 in glycosylphosphatidylinositol (GPI) anchor biosynthesis, this severe syndrome can be assigned to the group of inherited GPI deficiency disorders, with which it shares remarkably similar clinical and neuroimaging features. ARV1 should be considered in the genetic screening of individuals with EIMFS.

ATP1A2- and ATP1A3-associated early profound epileptic encephalopathy and polymicrogyria

Constitutional heterozygous mutations of ATP1A2 and ATP1A3, encoding for two distinct isoforms of the Na+/K+-ATPase (NKA) alpha-subunit, have been associated with familial hemiplegic migraine (ATP1A2), alternating hemiplegia of childhood (ATP1A2/A3), rapid-onset dystonia-parkinsonism, cerebellar ataxia-areflexia-progressive optic atrophy, and relapsing encephalopathy with cerebellar ataxia (all ATP1A3). A few reports have described single individuals with heterozygous mutations of ATP1A2/A3 associated with severe childhood epilepsies. Early lethal hydrops fetalis, arthrogryposis, microcephaly, and polymicrogyria have been associated with homozygous truncating mutations in ATP1A2. We investigated the genetic causes of developmental and epileptic encephalopathies variably associated with malformations of cortical development in a large cohort and identified 22 patients with de novo or inherited heterozygous ATP1A2/A3 mutations. We characterized clinical, neuroimaging and neuropathological findings, performed in silico and in vitro assays of the mutations' effects on the NKA-pump function, and studied genotype-phenotype correlations. Twenty-two patients harboured 19 distinct heterozygous mutations of ATP1A2 (six patients, five mutations) and ATP1A3 (16 patients, 14 mutations, including a mosaic individual). Polymicrogyria occurred in 10 (45%) patients, showing a mainly bilateral perisylvian pattern. Most patients manifested early, often neonatal, onset seizures with a multifocal or migrating pattern. A distinctive, 'profound' phenotype, featuring polymicrogyria or progressive brain atrophy and epilepsy, resulted in early lethality in seven patients (32%). In silico evaluation predicted all mutations to be detrimental. We tested 14 mutations in transfected COS-1 cells and demonstrated impaired NKA-pump activity, consistent with severe loss of function. Genotype-phenotype analysis suggested a link between the most severe phenotypes and lack of COS-1 cell survival, and also revealed a wide continuum of severity distributed across mutations that variably impair NKA-pump activity. We performed neuropathological analysis of the whole brain in two individuals with polymicrogyria respectively related to a heterozygous ATP1A3 mutation and a homozygous ATP1A2 mutation and found close similarities with findings suggesting a mainly neural pathogenesis, compounded by vascular and leptomeningeal abnormalities. Combining our report with other studies, we estimate that ∼5% of mutations in ATP1A2 and 12% in ATP1A3 can be associated with the severe and novel phenotypes that we describe here. Notably, a few of these mutations were associated with more than one phenotype. These findings assign novel, 'profound' and early lethal phenotypes of developmental and epileptic encephalopathies and polymicrogyria to the phenotypic spectrum associated with heterozygous ATP1A2/A3 mutations and indicate that severely impaired NKA pump function can disrupt brain morphogenesis.

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.

Refining the mutational spectrum and gene-phenotype correlates in pontocerebellar hypoplasia: results of a multicentric study

BACKGROUND

Pontocerebellar hypoplasias (PCH) comprise a group of genetically heterogeneous disorders characterised by concurrent hypoplasia of the pons and the cerebellum and variable clinical and imaging features. The current classification includes 13 subtypes, with ~20 known causative genes. Attempts have been made to delineate the phenotypic spectrum associated to specific PCH genes, yet clinical and neuroradiological features are not consistent across studies, making it difficult to define gene-specific outcomes.

METHODS

We performed deep clinical and imaging phenotyping in 56 probands with a neuroradiological diagnosis of PCH, who underwent NGS-based panel sequencing of PCH genes and MLPA for CASK rearrangements. Next, we conducted a phenotype-based unsupervised hierarchical cluster analysis to investigate associations between genes and specific phenotypic clusters.

RESULTS

A genetic diagnosis was obtained in 43 probands (77%). The most common causative gene was CASK, which accounted for nearly half cases (45%) and was mutated in females and occasionally in males. The European founder mutation p.Ala307Ser in TSEN54 and pathogenic variants in EXOSC3 accounted for 18% and 9% of cases, respectively. VLDLR, TOE1 and RARS2 were mutated in single patients. We were able to confirm only few previously reported associations, including jitteriness and clonus with TSEN54 and lower motor neuron signs with EXOSC3. When considering multiple features simultaneously, a clear association with a phenotypic cluster only emerged for EXOSC3.

CONCLUSION

CASK represents the major PCH causative gene in Italy. Phenotypic variability associated with the most common genetic causes of PCH is wider than previously thought, with marked overlap between CASK and TSEN54-associated disorders.

Enzymatic diagnosis of neuronal lipofuscinoses in dried blood spots using substrates for concomitant tandem mass spectrometry and fluorimetry

Neuronal ceroid lipofuscinoses (NCLs) are a group of neurodegenerative diseases predominantly in childhood that are characterized by psychomotor deterioration, epilepsy, and early death of patients. The NCLs analyzed in the present study are caused by defects of the specific enzymes, CLN1 (palmitoyl protein thioesterase 1; PPT1), CLN2 (tripeptidyl peptidase 1; TPP1), and CLN10 (cathepsin D). Specific and sensitive diagnostic assays of NCLs were the main goal of this study. They are of increasing importance, particularly since enzyme replacement therapy (ERT) for NCL2 has recently become available for clinical treatment, and ERTs for further NCLs are under development. Here, we report specific and sensitive determinations for CLN1, CLN2, and CLN10 on dried blood spots by tandem mass spectrometry using multiple reaction monitoring mass spectrometry (MRM-MS). Identical substrates suitable for (i) fluorimetric determination of single enzymes and (ii) for MRM-MS determination of multiple enzymes were synthesized by chemical coupling of alkyl-umbelliferone building blocks with the corresponding peptidyl-substrate groups recognized by the target enzyme. Enzymatic determinations were performed both by fluorimetry and MRM-MS in patients with NCL1, NCL2, and NCL10 and showed good agreement in single assays. Moreover, duplex and triplex determinations were successfully performed for NCL1, NCL2, and NCL10. Specific peptidyl-(4-alkyl-umbelliferone) substrates were also synthesized for mass spectrometric determinations of different cathepsins (cathepsins-D, -F, and -B), to provide a differentiation of proteolytic specificities.

Electrophysiological Profile Remodeling via Selective Suppression of Voltage-Gated Currents by CLN1/PPT1 Overexpression in Human Neuronal-Like Cells

CLN1 disease (OMIM #256730) is an inherited neurological disorder of early childhood with epileptic seizures and premature death. It is associated with mutations in CLN1 coding for Palmitoyl-Protein Thioesterase 1 (PPT1), a lysosomal enzyme which affects the recycling and degradation of lipid-modified (S-acylated) proteins by removing palmitate residues. Transcriptomic evidence from a neuronal-like cellular model derived from differentiated SH-SY5Y cells disclosed the potential negative roles of CLN1 overexpression, affecting the elongation of neuronal processes and the expression of selected proteins of the synaptic region. Bioinformatic inquiries of transcriptomic data pinpointed a dysregulated expression of several genes coding for proteins related to voltage-gated ion channels, including subunits of calcium and potassium channels (VGCC and VGKC). In SH-SY5Y cells overexpressing CLN1 (SH-CLN1 cells), the resting potential and the membrane conductance in the range of voltages close to the resting potential were not affected. However, patch-clamp recordings indicated a reduction of Ba²⁺ currents through VGCC of SH-CLN1 cells; Ca²⁺ imaging revealed reduced Ca²⁺ influx in the same cellular setting. The results of the biochemical and morphological investigations of CACNA2D2/α₂δ-2, an accessory subunit of VGCC, were in accordance with the downregulation of the corresponding gene and consistent with the hypothesis that a lower number of functional channels may reach the plasma membrane. The combined use of 4-AP and NS-1643, two drugs with opposing effects on K_v11 and K_v12 subfamilies of VGKC coded by the KCNH gene family, provides evidence for reduced functional K_v12 channels in SH-CLN1 cells, consistent with transcriptomic data indicating the downregulation of KCNH4. The lack of compelling evidence supporting the palmitoylation of many ion channels subunits investigated in this study stimulates inquiries about the role of PPT1 in the trafficking of channels to the plasma membrane. Altogether, these results indicate a reduction of functional voltage-gated ion channels in response to CLN1/PPT1 overexpression in differentiated SH-SY5Y cells and provide new insights into the altered neuronal excitability which may underlie the severe epileptic phenotype of CLN1 disease. It remains to be shown if remodeling of such functional channels on plasma membrane can occur as a downstream effect of CLN1 disease.

Proteomic and functional analyses in disease models reveal CLN5 protein involvement in mitochondrial dysfunction

CLN5 disease is a rare form of late-infantile neuronal ceroid lipofuscinosis (NCL) caused by mutations in the CLN5 gene that encodes a protein whose primary function and physiological roles remains unresolved. Emerging lines of evidence point to mitochondrial dysfunction in the onset and progression of several forms of NCL, offering new insights into putative biomarkers and shared biological processes. In this work, we employed cellular and murine models of the disease, in an effort to clarify disease pathways associated with CLN5 depletion. A mitochondria-focused quantitative proteomics approach followed by functional validations using cell biology and immunofluorescence assays revealed an impairment of mitochondrial functions in different CLN5 KO cell models and in Cln5 - /- cerebral cortex, which well correlated with disease progression. A visible impairment of autophagy machinery coupled with alterations of key parameters of mitophagy activation process functionally linked CLN5 protein to the process of neuronal injury. The functional link between impaired cellular respiration and activation of mitophagy pathways in the human CLN5 disease condition was corroborated by translating organelle-specific proteome findings to CLN5 patients' fibroblasts. Our study highlights the involvement of CLN5 in activation of mitophagy and mitochondrial homeostasis offering new insights into alternative strategies towards the CLN5 disease treatment.

CLN8 is an endoplasmic reticulum cargo receptor that regulates lysosome biogenesis

Organelle biogenesis requires proper transport of proteins from their site of synthesis to their target subcellular compartment^1–3. Lysosomal enzymes are synthesized in the endoplasmic reticulum (ER) and traffic through the Golgi complex before being transferred to the endolysosomal system^4–6, but how they are transferred from the ER to the Golgi is unknown. Here we show that ER-to-Golgi transfer of lysosomal enzymes requires CLN8, an ER-associated membrane protein whose loss of function leads to the lysosomal storage disorder, Neuronal Ceroid Lipofuscinosis 8 (a type of Batten disease)⁷. ER-to-Golgi trafficking of CLN8 requires interaction with the COPII and COPI machineries via specific export and retrieval signals localized in the cytosolic C-terminus of CLN8. CLN8 deficiency leads to depletion of soluble enzymes in the lysosome, thus impairing lysosome biogenesis. Binding to lysosomal enzymes requires CLN8’s second luminal loop and is abolished by some disease-causing mutations within this region. Our data establish an unanticipated example of an ER receptor serving the biogenesis of an organelle and suggest that impaired transport of lysosomal enzymes underlies Batten disease caused by mutations in CLN8.

The Networks of Genes Encoding Palmitoylated Proteins in Axonal and Synaptic Compartments Are Affected in PPT1 Overexpressing Neuronal-Like Cells

CLN1 disease (OMIM #256730) is an early childhood ceroid-lipofuscinosis associated with mutated CLN1, whose product Palmitoyl-Protein Thioesterase 1 (PPT1) is a lysosomal enzyme involved in the removal of palmitate residues from S-acylated proteins. In neurons, PPT1 expression is also linked to synaptic compartments. The aim of this study was to unravel molecular signatures connected to CLN1. We utilized SH-SY5Y neuroblastoma cells overexpressing wild type CLN1 (SH-p.wtCLN1) and five selected CLN1 patients’ mutations. The cellular distribution of wtPPT1 was consistent with regular processing of endogenous protein, partially detected inside Lysosomal Associated Membrane Protein 2 (LAMP2) positive vesicles, while the mutants displayed more diffuse cytoplasmic pattern. Transcriptomic profiling revealed 802 differentially expressed genes (DEGs) in SH-p.wtCLN1 (as compared to empty-vector transfected cells), whereas the number of DEGs detected in the two mutants (p.L222P and p.M57Nfs*45) was significantly lower. Bioinformatic scrutiny linked DEGs with neurite formation and neuronal transmission. Specifically, neuritogenesis and proliferation of neuronal processes were predicted to be hampered in the wtCLN1 overexpressing cell line, and these findings were corroborated by morphological investigations. Palmitoylation survey identified 113 palmitoylated protein-encoding genes in SH-p.wtCLN1, including 25 ones simultaneously assigned to axonal growth and synaptic compartments. A remarkable decrease in the expression of palmitoylated proteins, functionally related to axonal elongation (GAP43, CRMP1 and NEFM) and of the synaptic marker SNAP25, specifically in SH-p.wtCLN1 cells was confirmed by immunoblotting. Subsequent, bioinformatic network survey of DEGs assigned to the synaptic annotations linked 81 DEGs, including 23 ones encoding for palmitoylated proteins. Results obtained in this experimental setting outlined two affected functional modules (connected to the axonal and synaptic compartments), which can be associated with an altered gene dosage of wtCLN1. Moreover, these modules were interrelated with the pathological effects associated with loss of PPT1 function, similarly as observed in the Ppt1 knockout mice and patients with CLN1 disease.

Phenotype and natural history of variant late infantile ceroid-lipofuscinosis 5

AIM

To characterize the phenotypic profile of a cohort of children affected with CLN5, a rare form of neuronal ceroid-lipofuscinosis (NCL), and to trace the features of the natural history of the disease.

METHOD

Records of 15 children (nine males, six females) were obtained from the data sets of the DEM-CHILD International NCL Registry. Disease progression was measured by rating six functional domains at different time points along the disease course. All patients underwent mutation analysis of the CLN5 gene and ultrastructural investigations of peripheral tissues. Expression of the gene product, pCLN5, was characterized in vitro in six patients.

RESULTS

Disease onset was at 2 to 7 years 6 months of age: impaired learning and cognition were the most common early symptoms. Seizures occurred relatively late (median age 8y) and were the presenting symptoms in two children. Nine mutations were detected in 30 alleles, including six mutations predicting a truncated protein. Mixed cytosomes were observed by electron microscopy. Differences of disease progression were observed in two groups of patients and could be related to their genetic profile.

INTERPRETATION

Clinical features in a multicentre cohort of patients with CLN5 confirm that cognitive difficulties are early clinical markers of this condition. Severe mutations were associated with a more rapid decline of neurological function.

Survey on treatments for primary headaches in 13 specialized juvenile Headache Centers: The first multicenter Italian study

AIM

The purpose of this retrospective multicenter study was to evaluate the use and the self-perceived efficacy and tolerability of pharmacological and non-pharmacological treatments in children and adolescents with primary headaches.

METHODS

Study of a cohort of children and adolescents diagnosed with primary headache, consecutively referred to 13 juvenile Italian Headache Centers. An ad hoc questionnaire was used for clinical data collection.

RESULTS

Among 706 patients with primary headaches included in the study, 637 cases with a single type of headache (migraine 76% - with and without aura in 10% and 67% respectively; tension-type headache 24%) were selected (mean age at clinical interview: 12 years). Acetaminophen and non-steroidal anti-inflammatory drugs (in particular ibuprofen) were commonly used to treat attacks, by 76% and 46% of cases respectively. Triptans were used overall by 6% of migraineurs and by 13% of adolescents with migraine, with better efficacy than acetaminophen and non-steroidal anti-inflammatory drugs. Preventive drugs were used by 19% of migraineurs and by 3% of subjects with tension-type headache. In migraineurs, flunarizine was the most frequently used drug (18%), followed by antiepileptic drugs (7%) and pizotifen (6%), while cyproheptadine, propanolol and amitriptyline were rarely used. Pizotifen showed the best perceived efficacy and tolerability. Melatonin and nutraceuticals were used by 10% and 32% of subjects, respectively, both for migraine and tension-type headache, with good results in terms of perceived efficacy and tolerability. Non-pharmacological preventive treatments (i.e. relaxation techniques, biofeedback, cognitive-behavioral therapy, acupuncture) were used only by 10% of cases (migraine 9%, tension-type headache 15%).

DISCUSSION

Non-steroidal anti-inflammatory drugs, especially ibuprofen, should be preferred to acetaminophen for acute attacks of migraine or tension-type headache, because they were usually more effective and well tolerated. Triptans could be used more frequently as first or almost second choice for treating migraine attack in adolescents. Non-pharmacological preventive treatments are recommended by some pediatric guidelines as first-line interventions for primary headaches and their use should be implemented in clinical practice. Prospective multicenter studies based on larger series are warranted to better understand the best treatment strategies for young people with primary headaches.