Niemann-Pick type C Suspicion Index tool: analyses by age and association of manifestations

Supranuclear Palsy as an Initial Presentation of the Adult-Onset Niemann-Pick Type C

(1) Background: Niemann-Pick type C1 (NP-C1) is a lysosomal storage disorder that results in the defective trafficking of cholesterol and other cellular lipids in the endosomal-lysosomal pathway. This rare autosomal recessive disorder presents in three forms based on the age of onset. The adult form presents in patients greater than 15 years of age but is rarely seen after the age of 30. Common symptoms of the late adult-onset category of NP-C1 include progressive cognitive impairment and ataxia, with psychiatric and movement disorders presenting less frequently than in other forms of NP-C1. Dystonic movement disorders present most frequently, along with chorea, myoclonus, and parkinsonism. Herein, we present a rare case of NP-C1, diagnosed at age 35 with an initial symptom of supranuclear palsy. The goal of the presented case is to highlight the importance of the neurological examination and an inclusive differential diagnosis in patients with new-onset supranuclear palsy. (2) Methods: A single case report. (3) Results: A 46-year-old male with a past medical history of NP-C1 was admitted to the hospital for respiratory distress. He was noted to have a supranuclear gaze palsy with partially preserved voluntary saccades to the right. His mother revealed that he first had difficulty moving his eyes at the age of 34. After multiple consultations and genetic testing one year later, he was diagnosed with NP-C1. (4) Conclusions: Because NP-C1 affects many regions of the brain responsible for eye movements, neurological eye assessments can be a useful tool in diagnoses. Furthermore, eye movement abnormalities may be the initial presenting symptom of NP-C1, predisposing patients to misdiagnosis with progressive supranuclear palsy and other conditions that may mimic early-stage NP-C1. Definitive diagnosis is achieved through genetic testing. Filipin staining test was the gold standard in the past. The NP-C Suspicion Index was developed to assist in diagnoses, but its efficacy is unclear with late adult-onset NP-C1. Although no cure exists, early identification can facilitate an improved symptom management course for patients. Miglustat, a glucosylceramide synthase (GCS) inhibitor, is the approved therapy in Europe specific to NP-C1 for slowing and preventing the neurological manifestations of NP-C1. Delays between symptom onset and treatment initiation are likely to result in poorer outcomes and a progression of neurological symptoms. High doses may present tolerance concerns, especially in cases of delayed treatment and advanced neurological deficit.

Peripheral immune system modulates Purkinje cell degeneration in Niemann-Pick disease type C1

Niemann-Pick disease type C1 (NPC1) is a fatal lysosomal storage disorder characterized by progressive neuronal degeneration. Its key pathogenic events remain largely unknown. We have, herein, found that neonatal BM-derived cell transplantation can ameliorate Purkinje cell degeneration in NPC1 mice. We subsequently addressed the impact of the peripheral immune system on the neuropathogenesis observed in NPC1 mice. The depletion of mature lymphocytes promoted NPC1 phenotypes, thereby suggesting a neuroprotective effect of lymphocytes. Moreover, the peripheral infusion of CD4-positive cells (specifically, of regulatory T cells) from normal healthy donor ameliorated the cerebellar ataxic phenotype and enhanced the survival of Purkinje cells. Conversely, the depletion of regulatory T cells enhanced the onset of the neurological phenotype. On the other hand, circulating inflammatory monocytes were found to be involved in the progression of Purkinje cell degeneration, whereas the depletion of resident microglia had little effect. Our findings reveal a novel role of the adaptive and the innate immune systems in NPC1 neuropathology.

The experience of living with Niemann-Pick type C: a patient and caregiver perspective

BACKGROUND

Niemann-Pick disease type C (NPC) is a rare inherited lysosomal storage disease typified by accumulation of cholesterol and other lipids in late endosomes/lysosomes, thereby resulting in a spectrum of neurological, psychiatric, and systemic symptoms (notably liver disease). Though it is well-known that NPC exacts a physical and emotional toll on both patients and caregivers, the burden of NPC can vary between patients, while the challenges of living with NPC can evolve over time (i.e., from time of diagnosis to the present day). To further grasp patient and caregiver perceptions and experiences with NPC, we carried out focus group discussions with pediatric and adult individuals with NPC (N = 19), with partial or full representation of the patient by their caregiver. Furthermore, we utilized our NPC focus group discussion to provide guidance on study design parameters and feasibility of prospective investigations aiming to characterize the central manifestations of NPC using neuroimaging, specifically, magnetic resonance imaging (MRI) methodology.

RESULTS

Focus group discussions revealed that neurological signs, including declining cognition, memory loss, and psychiatric symptoms, as well as increasingly impaired mobility and motor function, are among the most pressing past and current concerns for patients and caregivers. Moreover, several participants also expressed concern over a loss of independence, social exclusion, and uncertainty for what the future holds. Caregivers described the challenges that participation in research poses, which included logistical difficulties mainly due to traveling with medical equipment and the need for sedation in a minority of patients when undergoing MRI.

CONCLUSIONS

The findings derived from focus group discussions highlight the outstanding challenges that NPC patients and their caregivers face daily, while also providing direction on the potential scope and feasibility of future studies focusing on the central phenotypes of NPC.

Eine Kinderkrankheit wird erwachsen

Zusammenfassung: Die Untersuchung von seltenen Erkrankungen ist aufgrund der geringen Anzahl an Patient_innen sowie einem häufig heterogenen, multisymptomatischen Erscheinungsbild deutlich erschwert. Als Beispiel für eine solche seltene Krankheit dient im Folgenden die progrediente, neurodegenerative Erbkrankheit Niemann-Pick Typ C (NPC), die lange Zeit als „Kinderkrankheit“ galt. Im Verlauf des letzten Jahrzehnts wurde jedoch auch ein substanzieller Anteil an erwachsenen NPC-Patient_innen diagnostiziert. Da zum klinischen Erscheinungsbild von erwachsenen NPC-Patient_innen wenig Umfassendes bekannt ist, widmet sich der Artikel diesem Thema und zeigt, inwieweit die Erkenntnisse zu Manifestationen sowie zur Krankheitsentwicklung von pädiatrischen auf erwachsene NPC-Patient_innen übertragbar sind. Die Darstellung von Erkrankungsmerkmalen der Subpopulationen pädiatrischer gegenüber jugendlicher bzw. erwachsener NPC-Patient_innen basiert auf der verfügbaren Literatur sowie Expertenmeinungen hinsichtlich der Epidemiologie, des genetischen Mutationsmusters, des klinischen Bildes einschließlich der Prodromalsymptome, der Progressionsrate, dem allgemeinen Behandlungsregime und den Therapieeffekten. Insgesamt erweist sich NPC als ein Krankheitskontinuum, basierend auf weitestgehend ähnlichen genetischen Mutationsmustern sowie einer sich in den Altersgruppen entsprechenden Pathophysiologie. Pädiatrische und jugendliche bzw. erwachsene Patient_innen sind durch diverse Facetten fortschreitender neuropsychologischer Manifestationen wie bspw. kognitive Defizite und deutliche Einschränkungen ihrer motorischen Fähigkeiten (einschließlich der Berücksichtigung von prodromalen Symptomen) gekennzeichnet. NPC verläuft bei Kindern sowie bei jugendlichen bzw. erwachsenen Patient_innen auf die ähnliche Weise – jedoch mit einer beschleunigten Progressionsrate und einer somit verkürzten Lebenserwartung, je jünger die Patient_innen bei erstmaligem Auftreten neurologischer Symptome sind. Jedoch weist die hohe Krankheitslast aller NPC-Patient_innen auf die Schwere dieser seltenen Stoffwechselkrankheit hin. Die Behandlung von NPC erfolgt altersunabhängig interdisziplinär. Es besteht bisher keine kausale Therapieoption.

Organ Weights in NPC1 Mutant Mice Partly Normalized by Various Pharmacological Treatment Approaches

Niemann-Pick Type C1 (NPC1, MIM 257220) is a rare, progressive, lethal, inherited autosomal-recessive endolysosomal storage disease caused by mutations in the NPC1 leading to intracellular lipid storage. We analyzed mostly not jet known alterations of the weights of 14 different organs in the BALB/cNctr-Npc1^m1N/-J Jackson Npc1 mice in female and male Npc1^+/+ and Npc1^-/- mice under various treatment strategies. Mice were treated with (i) no therapy, (ii) vehicle injection, (iii) a combination of miglustat, allopregnanolone, and 2-hydroxypropyl-ß-cyclodextrin (HPßCD), (iv) miglustat, and (v) HPßCD alone starting at P7 and repeated weekly throughout life. The 12 respective male and female wild-type mice groups were evaluated in parallel. In total, 351 mice (176 Npc1^+/+, 175 Npc1^-/-) were dissected at P65. In both sexes, the body weights of None and Sham Npc1^-/- mice were lower than those of respective Npc1^+/+ mice. The influence of the Npc1 mutation and/or sex on the weights of various organs, however, differed considerably. In males, Npc1^+/+ and Npc1^-/- mice had comparable absolute weights of lungs, spleen, and adrenal glands. In Npc1^-/- mice, smaller weights of hearts, livers, kidneys, testes, vesicular, and scent glands were found. In female Npc1^-/- mice, ovaries, and uteri were significantly smaller. In Npc1^-/- mice, relative organ weights, i.e., normalized with body weights, were sex-specifically altered to different extents by the different therapies. The combination of miglustat, allopregnanolone, and the sterol chelator HPßCD partly normalized the weights of more organs than miglustat or HPßCD mono-therapies.

Potential Composite Digenic Contribution of NPC1 and NOD2 Leading to Atypical Lethal Niemann-Pick Type C with Initial Crohn’s Disease-like Presentation: Genotype-Phenotype Correlation Study

Niemann–Pick disease type C (NPC) is an autosomal recessive neurovisceral disease characterized by progressive neurodegeneration with variable involvement of multisystemic abnormalities. Crohn’s disease (CD) is an inflammatory bowel disease (IBD) with a multifactorial etiology influenced by variants in NOD2. Here, we investigated a patient with plausible multisystemic overlapping manifestations of both NPC and CD. Her initial hospitalization was due to a prolonged fever and non-bloody diarrhea. A few months later, she presented with recurrent skin tags and anal fissures. Later, her neurological and pulmonary systems progressively deteriorated, leading to her death at the age of three and a half years. Differential diagnosis of her disease encompassed a battery of clinical testing and genetic investigations. The patient’s clinical diagnosis was inconclusive. Specifically, the histopathological findings were directed towards an IBD disease. Nevertheless, the diagnosis of IBD was not consistent with the patient’s subsequent neurological and pulmonary deterioration. Consequently, we utilized a genetic analysis approach to guide the diagnosis of this vague condition. Our phenotype–genotype association attempts led to the identification of candidate disease-causing variants in both NOD2 and NPC1. In this study, we propose a potential composite digenic impact of these two genes as the underlying molecular etiology. This work lays the foundation for future functional and mechanistic studies to unravel the digenic role of NOD2 and NPC1.

Eye Movement Disorders in Movement Disorders

Oculomotor assessment is an essential element of the neurological clinical examination and is particularly important when evaluating patients with movements disorders. Most of the brain is involved in oculomotor control, and thus many neurological conditions present with oculomotor abnormalities. Each of the different classes of eye movements and their features can provide important information that can facilitate differential diagnosis. This educational review presents a clinical approach to eye movement abnormalities that are commonly seen in parkinsonism, ataxia, dystonia, myoclonus, tremor, and chorea. In parkinsonism, subtle signs such as prominent square wave jerks, impaired vertical optokinetic nystagmus, and/or the "round the houses" sign suggest early progressive supranuclear gaze palsy before vertical gaze is restricted. In ataxia, nystagmus is common, but other findings such as oculomotor apraxia, supranuclear gaze palsy, impaired fixation, or saccadic pursuit can contribute to diagnoses such as ataxia with oculomotor apraxia, Niemann-Pick type C, or ataxia telangiectasia. Opsoclonus myoclonus and oculopalatal myoclonus present with characteristic phenomenology and are usually easy to identify. The oculomotor exam is usually unremarkable in isolated dystonia, but oculogyric crisis is a medical emergency and should be recognized and treated in a timely manner. Gaze impersistence in a patient with chorea suggests Huntington's disease, but in a patient with dystonia or tremor, Wilson's disease is more likely. Finally, functional eye movements can reinforce the clinical impression of a functional movement disorder.

Correlation of age of onset and clinical severity in Niemann-Pick disease type C1 with lysosomal abnormalities and gene expression

Niemann-Pick disease type C1 (NPC1) is a rare, prematurely fatal lysosomal storage disorder which exhibits highly variable severity and disease progression as well as a wide-ranging age of onset, from perinatal stages to adulthood. This heterogeneity has made it difficult to obtain prompt diagnosis and to predict disease course. In addition, small NPC1 patient sample sizes have been a limiting factor in acquiring genome-wide transcriptome data. In this study, primary fibroblasts from an extensive cohort of 41 NPC1 patients were used to validate our previous findings that the lysosomal quantitative probe LysoTracker can be used as a predictor for age of onset and disease severity. We also examined the correlation between these clinical parameters and RNA expression data from primary fibroblasts and identified a set of genes that were significantly associated with lysosomal defects or age of onset, in particular neurological symptom onset. Hierarchical clustering showed that these genes exhibited distinct expression patterns among patient subgroups. This study is the first to collect transcriptomic data on such a large scale in correlation with clinical and cellular phenotypes, providing a rich genomic resource to address NPC1 clinical heterogeneity and discover potential biomarkers, disease modifiers, or therapeutic targets.

Impacts and Burden of Niemann pick Type-C: a patient and caregiver perspective

Background

Niemann-Pick disease type C (NPC) is a debilitating condition that impacts patients’ and caregivers’ quality of life (QOL) and reduces the patient’s life expectancy. Since there is little qualitative research from the perspective of patients and family caregivers, this study explored the impact of NPC on patients’ and caregivers’ daily lives to understand the burden of disease.

Results

A survey of caregivers for patients with NPC and adult patients with NPC (n = 49; patient age: 13 months–65 years) assessed NPC severity, importance of NPC symptoms, and how symptoms impacted patients’ and caregivers’ activities of daily living (ADLs) and health-related QOL (HRQOL). Follow-up interviews with a subset of survey participants (n = 28) explored the ranking of NPC symptom importance and impact on ADLs and HRQOL. Findings indicated that the most important manifestations of NPC were ambulation, swallowing, speech, fine motor skills, and cognition, which were those that had the most significant impact on ADLs and HRQOL. A wide range of ADLs were affected by NPC, mainly eating/drinking and the ability to perform daily tasks, including self-care, communicating, participating in school or work, and moving indoors as well as outside the home. Along with these impacts, there was an increased risk of experiencing dangerous or life-threatening situations leading to loss of patient independence and additional caregiver burden, often requiring changes in lifestyle such as giving up work. All aspects of patients’ and caregivers’ HRQOL were affected. Participants reported feelings of social isolation, loss of enjoyment in activities (patients), and feelings of sadness or worry (caregivers).

Conclusions

Ambulation, swallowing, speech, fine motor skills, and cognition are important manifestations of NPC. ADLs and HRQOL were impaired in the majority of patients as well as their caregivers. The findings were independent of current age, age of onset of symptoms, and level of NPC disease-related disability; however, the impact increased at higher levels of disease disability. Knowing the impact of NPC on patients and caregivers is important for understanding the lived experience of NPC and for identifying potential areas of support.

Efficacy and safety of arimoclomol in Niemann-Pick disease type C: Results from a double-blind, randomised, placebo-controlled, multinational phase 2/3 trial of a novel treatment

Niemann-Pick disease type C (NPC) is a rare, genetic, progressive neurodegenerative disorder with high unmet medical need. We investigated the safety and efficacy of arimoclomol, which amplifies the heat shock response to target NPC protein misfolding and improve lysosomal function, in patients with NPC. In a 12-month, prospective, randomised, double-blind, placebo-controlled, phase 2/3 trial (ClinicalTrials.gov identifier: NCT02612129), patients (2-18 years) were randomised 2:1 to arimoclomol:placebo, stratified by miglustat use. Routine clinical care was maintained. Arimoclomol was administered orally three times daily. The primary endpoint was change in 5-domain NPC Clinical Severity Scale (NPCCSS) score from baseline to 12 months. Fifty patients enrolled; 42 completed. At month 12, the mean progression from baseline in the 5-domain NPCCSS was 0.76 with arimoclomol vs 2.15 with placebo. A statistically significant treatment difference in favour of arimoclomol of -1.40 (95% confidence interval: -2.76, -0.03; P = .046) was observed, corresponding to a 65% reduction in annual disease progression. In the prespecified subgroup of patients receiving miglustat as routine care, arimoclomol resulted in stabilisation of disease severity over 12 months with a treatment difference of -2.06 in favour of arimoclomol (P = .006). Adverse events occurred in 30/34 patients (88.2%) receiving arimoclomol and 12/16 (75.0%) receiving placebo. Fewer patients had serious adverse events with arimoclomol (5/34, 14.7%) vs placebo (5/16, 31.3%). Treatment-related serious adverse events (n = 2) included urticaria and angioedema. Arimoclomol provided a significant and clinically meaningful treatment effect in NPC and was well tolerated.

Niemann-Pick disease type C in Palestine: genotype and phenotype of sixteen patients and report of a novel mutation in the NPC1 gene

Background

Niemann–Pick disease type C (NPC) is an autosomal recessive, neurodegenerative disease caused by mutations in either the NPC1 or NPC2 genes. Mutations in these genes are associated with abnormal endosomal–lysosomal trafficking, resulting in the accumulation of tissue-specific lipids in lysosomes.

Methods

We described sixteen patients with NPC diagnosed between the age of 1 month and 30 years at two tertiary care centers in Palestine. The clinical phenotype, brain magnetic resonance imaging (MRI), and molecular genetic analysis data were reviewed.

Results

The diagnosis was confirmed by molecular analysis in all patients. Fourteen out of sixteen patients were homozygous for the NPC1 p.G992W variant. Among them, most were categorized as having the late-infantile neurological form of disease onset. They predominantly manifested with early-onset visceral manifestations in the form of hepatosplenomegaly and prolonged neonatal jaundice, and late-onset neuropsychiatric manifestations in the form of vertical supranuclear gaze palsy (VSGP), ataxia, cognitive impairment and seizures. Brain MRI in 6 patients was normal in 5 or consistent with cerebellar hemisphere atrophy in 1 of them. Two other mutations were identified in the NPC1 gene, of which p.V845Cfs*24 was novel.

Conclusions

Our results revealed phenotypic heterogeneity of NPC even within the same genotype, and add to the increasingly recognized evidence that cholestatic jaundice and hepatosplenomegaly during infancy, should alert the physician for the possibility of NPC. We reported a novel mutation in the NPC1 gene further expanding its genotype.

Psychosis symptoms associated with Niemann-Pick disease type C

Niemann-Pick disease type C (NP-C) is a severe neurovisceral lipid storage disease that results in the accumulation of unesterified cholesterol in lysosomes or endosomes. The clinical presentations of NP-C are variable which include visceral symptoms, neurologic symptoms and psychiatric symptoms. Psychosis is the most common psychiatric manifestation of NP-C and is indistinguishable from a typical psychosis presentation of schizophrenia. The common psychotic presentations in NP-C include visual hallucinations, delusions, auditory hallucinations and thought disorders. Psychosis symptoms are more common in adult or adolescent-onset forms compared with pediatric-onset forms. The underlying pathophysiology of psychosis in NP-C is most probably due to dysconnectivity particularly between frontotemporal connectivity and subcortical structures. NP-C sometimes is mistaken for schizophrenia which causes delay in treatment due to lack of awareness and literature review. This review aims to summarize the relevant case reports on psychosis symptoms in NP-C and discuss the genetics and pathophysiology underlying the condition.

Gender-Specific Effects of Two Treatment Strategies in a Mouse Model of Niemann-Pick Disease Type C1

In a mouse model of Niemann-Pick disease type C1 (NPC1), a combination therapy (COMBI) of miglustat (MIGLU), the neurosteroid allopregnanolone (ALLO) and the cyclic oligosaccharide 2-hydroxypropyl-β-cyclodextrin (HPßCD) has previously resulted in, among other things, significantly improved motor function. The present study was designed to compare the therapeutic effects of the COMBI therapy with that of MIGLU or HPßCD alone on body and brain weight and the behavior of NPC1^−/− mice in a larger cohort, with special reference to gender differences. A total of 117 NPC1^−/− and 123 NPC1^+/+ mice underwent either COMBI, MIGLU only, HPßCD only, or vehicle treatment (Sham), or received no treatment at all (None). In male and female NPC1^−/− mice, all treatments led to decreased loss of body weight and, partly, brain weight. Concerning motor coordination, as revealed by the accelerod test, male NPC1^−/− mice benefited from COMBI treatment, whereas female mice benefited from COMBI, MIGLU, and HPßCD treatment. As seen in the open field test, the reduced locomotor activity of male and female NPC1^−/− mice was not significantly ameliorated in either treatment group. Our results suggest that in NPC1^−/− mice, each drug treatment scheme had a beneficial effect on at least some of the parameters evaluated compared with Sham-treated mice. Only in COMBI-treated male and female NPC^+/+ mice were drug effects seen in reduced body and brain weights. Upon COMBI treatment, the increased dosage of drugs necessary for anesthesia in Sham-treated male and female NPC1^−/− mice was almost completely reduced only in the female groups.

Clinical disease progression and biomarkers in Niemann-Pick disease type C: a prospective cohort study

Background

Niemann–Pick disease type C (NPC) is a rare, progressive, neurodegenerative disease associated with neurovisceral manifestations resulting from lysosomal dysfunction and aberrant lipid accumulation. A multicentre, prospective observational study (Clinical Trials.gov ID: NCT02435030) of individuals with genetically confirmed NPC1 or NPC2 receiving routine clinical care was conducted, to prospectively characterize and measure NPC disease progression and to investigate potential NPC-related biomarkers versus healthy individuals. Progression was measured using the abbreviated 5-domain NPC Clinical Severity Scale (NPCCSS), 17-domain NPCCSS and NPC clinical database (NPC-cdb) score. Cholesterol esterification and heat shock protein 70 (HSP70) levels were assessed from peripheral blood mononuclear cells (PBMCs), cholestane-3β,5α-,6β-triol (cholestane-triol) from serum, and unesterified cholesterol from both PBMCs and skin biopsy samples. The inter- and intra-rater reliability of the 5-domain NPCCSS was assessed by 13 expert clinicians’ rating of four participants via video recordings, repeated after ≥ 3 weeks. Intraclass correlation coefficients (ICCs) were calculated.

Results

Of the 36 individuals with NPC (2–18 years) enrolled, 31 (86.1%) completed the 6–14-month observation period; 30/36 (83.3%) were receiving miglustat as part of routine clinical care. A mean (± SD) increase in 5-domain NPCCSS scores of 1.4 (± 2.9) was observed, corresponding to an annualized progression rate of 1.5. On the 17-domain NPCCSS, a mean (± SD) progression of 2.7 (± 4.0) was reported. Compared with healthy individuals, the NPC population had significantly lower levels of cholesterol esterification (p < 0.0001), HSP70 (p < 0.0001) and skin unesterified cholesterol (p = 0.0006). Cholestane-triol levels were significantly higher in individuals with NPC versus healthy individuals (p = 0.008) and correlated with the 5-domain NPCCSS (Spearman’s correlation coefficient = 0.265, p = 0.0411). The 5-domain NPCCSS showed high ICC agreement in inter-rater reliability (ICC = 0.995) and intra-rater reliability (ICC = 0.937).

Conclusions

Progression rates observed were consistent with other reports on disease progression in NPC. The 5-domain NPCCSS reliability study supports its use as an abbreviated alternative to the 17-domain NPCCSS that focuses on the most relevant domains of the disease. The data support the use of cholestane-triol as a disease monitoring biomarker and the novel methods of measuring unesterified cholesterol could be applicable to support NPC diagnosis. Levels of HSP70 in individuals with NPC were significantly decreased compared with healthy individuals.

Trial registration

CT-ORZY-NPC-001: ClincalTrials.gov NCT02435030, Registered 6 May 2015, https://clinicaltrials.gov/ct2/show/NCT02435030; EudraCT 2014–005,194-37, Registered 28 April 2015, https://www.clinicaltrialsregister.eu/ctr-search/trial/2014-005194-37/DE. OR-REL-NPC-01: Unregistered.

Inherited disorders of lysosomal membrane transporters

Disorders caused by defects in lysosomal membrane transporters form a distinct subgroup of lysosomal storage disorders (LSDs). To date, defects in only 10 lysosomal membrane transporters have been associated with inherited disorders. The clinical presentations of these diseases resemble the phenotypes of other LSDs; they are heterogeneous and often present in children with neurodegenerative manifestations. However, for pathomechanistic and therapeutic studies, lysosomal membrane transport defects should be distinguished from LSDs caused by defective hydrolytic enzymes. The involved proteins differ in function, localization, and lysosomal targeting, and the diseases themselves differ in their stored material and therapeutic approaches. We provide an overview of the small group of disorders of lysosomal membrane transporters, emphasizing discovery, pathomechanism, clinical features, diagnostic methods and therapeutic aspects. We discuss common aspects of lysosomal membrane transporter defects that can provide the basis for preclinical research into these disorders.

Treatment outcomes following continuous miglustat therapy in patients with Niemann-Pick disease Type C: a final report of the NPC Registry

BACKGROUND

Niemann-Pick disease Type C (NP-C) is a rare, progressive neurodegenerative disorder characterized by progressive neurodegeneration and premature death. We report data at closure of the NPC Registry that describes the natural history, disease course and treatment experience of NP-C patients in a real-world setting.

METHODS

The NPC Registry was a prospective observational cohort study that ran between September 2009 and October 2017. Patients with a confirmed diagnosis of NP-C were enrolled regardless of treatment status. All patients underwent clinical assessments and medical care as determined by their physicians; data were collected through a secure internet-based portal.

RESULTS

At closure on October 19, 2017, 472 patients from 22 countries were enrolled in the NPC Registry. Mean (standard deviation) age at enrollment was 21.2 (15.0) years, and 51.9% of patients were male. First neurological symptom onset occurred during the early-infantile (< 2 years), late-infantile (2 to < 6 years), juvenile (6 to < 15 years), or adolescent/adult (≥ 15 years) periods in 13.5, 25.6, 31.8, and 29.1% of cases, respectively. The most frequent neurological manifestations prior to enrollment included ataxia (67.9%), vertical supranuclear gaze palsy (67.4%), dysarthria (64.7%), cognitive impairment (62.7%), dysphagia (49.1%), and dystonia (40.2%). During infancy, splenomegaly and hepatomegaly were frequent (n = 199/398 [50%] and n = 147/397 [37.0%], respectively) and persisted in most affected patients. Of the 472 enrolled patients, 241 were continuously treated with miglustat during the NPC Registry observation period, of whom 172 of these 241 patients were treated continuously for ≥12 months. A composite disability score that assesses impairment of ambulation, manipulation, language, and swallowing was highest in the early-infantile population and lowest in the adolescent/adult population. Among the continuous miglustat therapy population, 70.5% of patients had improved or had stable disease (at least 3 of the 4 domains having a decreased or unchanged score between enrollment and last follow-up). The NPC Registry did not identify any new safety signals associated with miglustat therapy.

CONCLUSIONS

The profiles of clinical manifestations in the final NPC Registry dataset agreed with previous clinical descriptions. Miglustat therapy was associated with a stabilization of neurological manifestations in most patients. The safety and tolerability of miglustat therapy was consistent with previous reports.

Recessive Ataxia Differential Diagnosis Algorithm (RADIAL) Versus Specific Niemann-Pick Type C Suspicion Indices: A Retrospective Algorithm Comparison

Early diagnosis of Niemann-Pick disease type C (NPC) is crucial to slow the progression of neurological manifestations. Different tools were developed to aid diagnosis of NPC, but to date, no study has compared their performance. We aimed to compare the RADIAL algorithm, intended for the differential diagnosis of autosomal recessive cerebellar ataxias (ARCAs) and NPC-specific suspicion indices (SIs). This study was a retrospective analysis of data from 834 patients with molecularly confirmed ARCAs, including 57 NPC cases (RADIAL cohort). We aimed to compare the algorithm performance of RADIAL (Top 1 and Top 3) with that of four SIs (Original, Refined, 2/3 and 2/7) in discriminating NPC cases and non-NPC cases. We also identified ARCAs closely related to NPC as those with low specificity to detect non-NPC cases and described differential and overlapping features with NPC. Overall, excellent sensitivity and specificity (> 0.90) were achieved with both RADIAL and SI tools for NPC cases. The highest sensitivity was attained with the 2/7 SI, Refined SI and Top 3 RADIAL algorithms. Top 1 and Top 3 RADIAL were the most specific tools, followed by the Original SI. The individual comparison of each ARCA revealed that Wilson disease, PLA2G6-associated neurodegeneration, and hypomyelinating leukodystrophy (POLR3A) are frequent NPC false positives (PLA2G6 and POL3A only with the SIs). Both RADIAL and SI diagnostic approaches showed strong discriminatory potential and may be useful screening tools in different clinical contexts.

Nosology and Phenomenology of Psychosis in Movement Disorders

Background

Psychotic symptoms, such as delusions and hallucinations, are part of the clinical picture of several conditions presenting movement disorders. Phenomenology and epidemiology of psychosis in Parkinson's disease have received wide attention; however, the presence of psychosis in other movement disorders is, comparatively, less well known.

Objectives

To review psychotic symptoms present in different movement disorders.

Methods

A comprehensive and structured literature search was performed to identify and analyze data on patients with movement disorders and comorbid psychosis.

Results

In monogenic parkinsonisms, such as PARK-GBA, PARK-LRRK2, and PARK-SNCA, visual hallucinations related to dopamine replacement therapy are frequent as well as are delusions in PARK-LRRK2 and PARK-SNCA, but not in PARK-GBA. Different types of delusions and hallucinations are found in Huntington's disease and other choreic disorders. In Tourette's syndrome, paranoid delusions as well as visual, olfactory, and auditory hallucinations have been described, which usually develop after an average of 10 years of disease. Delusions in ataxias are more frequent in ATX-TBP, ATX-ATN1, and ATX-ATXN3, whereas it is rare in Friedreich's ataxia. Psychosis is also a prominent and frequent clinical feature in Fahr's disease, Wilson's disease, neurodegeneration with brain iron accumulation, and some lysosomal storage disorders, whereas it is uncommon in atypical parkinsonisms and dystonia. Psychosis usually occurs at late disease stages, but may appear as onset symptoms of the disease, especially in Wilson's disease, Huntington's disease, late-onset Tays-Sachs, and Niemann-Pick.

Conclusion

Psychosis is a frequent comorbidity in most hyper- and hypokinetic movement disorders. Appropriate recognition is relevant both in the early and late disease stages.

Evaluation of different suspicion indices in identifying patients with Niemann-Pick disease Type C in clinical practice: a post hoc analysis of a retrospective chart review

BACKGROUND

Niemann-Pick disease Type C (NP-C) is a lysosomal lipid storage disorder with varying symptomatology depending on the age of onset. The diagnosis of NP-C is challenging due to heterogeneous nonspecific clinical presentation of the disease. NP-C Suspicion Index (SI) was developed to aid screening and identification of patients with suspicion of NP-C for further clinical evaluation. Here we assess the performance of five NP-C SI models to identify patients with NP-C compared with clinical practice to determine the best SI model for identification of each clinical form of NP-C by age.

METHODS

This was a post hoc analysis of a retrospective chart review of patient data collected from five expert NP-C centers. The study assessed the proportion of patients with NP-C who could have been identified using the Original SI, Refined SI, 2/7 SI, 2/3 SI, and Early-Onset SI and evaluated the performance of each SI against clinical practice. A score above a threshold of 70 points for the Original SI, 40 points for the Refined SI, 6 points for the Early-Onset SI, and 2 points for the 2/7 and 2/3 SIs represented identification of NP-C.

RESULTS

The study included 63 patients, and of these, 23.8% had a family history of NP-C. Of the available SI tools, the Refined SI performed well in identifying patients with NP-C across all age groups (77.8% infantile, 100% juvenile and 100% adult groups), and earlier identification than clinical diagnosis would have been possible in 50.0% of infantile, 72.7% of juvenile and 87.0% of adult patients. Patients who were not detected by the Refined SI prior to clinical diagnosis mainly presented with delayed developmental milestones, visceral manifestations, neurologic hypotonia, clumsiness, ataxia, vertical supranuclear gaze palsy, parent or siblings with NP-C, dysarthria/dysphagia and psychotic symptoms.

CONCLUSION

This study demonstrated the applicability of various SI models for screening and identification of patients with NP-C for further clinical evaluation. Although NP-C is rare and the patient population is limited, this study was conducted in a real-world setting and confirms SI models as useful screening tools that facilitate identification of patients with NP-C earlier in their disease course.

Disease characteristics, prognosis and miglustat treatment effects on disease progression in patients with Niemann-Pick disease Type C: an international, multicenter, retrospective chart review

BACKGROUND

Niemann-Pick disease Type C (NP-C) is a lysosomal lipid storage disorder characterized by progressive neurodegenerative symptomatology. The signs and symptoms of NP-C vary with age at disease onset, and available therapies are directed at alleviating symptoms and stabilizing disease progression. We report the characteristics and factors related to disease progression, and analyze the effect of miglustat treatment on disease progression and patient survival using NP-C disability scales.

METHODS

This retrospective, observational chart review included patients with NP-C from five expert NP-C centers. Patient disability scores were recorded using three published NP-C disability scales, and a unified disability scale was developed to allow comparison of data from each scale. Disease progression was represented by scores on the unified NP-C disability scale. Patients were stratified as infantile (< 4 years), juvenile (≥ 4 - < 16 years), and adult (≥ 16 years) based on age at diagnosis, and treated ≥1 year and non-treated/treated < 1 year based on the duration of miglustat treatment.

RESULTS

The analysis included 63 patients; the majority (61.9%) were on miglustat therapy for ≥1 year. Ataxia and clumsiness/frequent fall were the most common neurologic symptoms across age groups, whereas, hypotonia and delayed developmental milestones were specific to infantile patients. In both infantile and juvenile patients, visceral signs preceded diagnosis and neurologic signs were noted at or shortly after diagnosis. Adult patients presented with a range of visceral, neurologic, and psychiatric signs in years preceding diagnosis. Patients on miglustat therapy for ≥1 year had a lower mean annual disease progression compared with those untreated/treated < 1 year (1.32 vs 3.54 points/year). A significant reduction in annual disease progression in infantile patients, and a trend towards reduced disease progression in juvenile patients after ≥1 year of miglustat treatment, translated into higher age at last contact or death in these groups.

CONCLUSIONS

The type and onset of symptoms varied across age groups and were consistent with descriptions of NP-C within the literature. Miglustat treatment was associated with a reduced rate of disability score worsening in infantile and juvenile patients, both in agreement with increased age at last contact.

Lysosomal storage disease overview

The lysosomal storage diseases (LSDs) are a group of inherited metabolic disorders that are caused for the most part by enzyme deficiencies within the lysosome resulting in accumulation of undegraded substrate. This storage process leads to a broad spectrum of clinical manifestations depending on the specific substrate and site of accumulation. Examples of LSDs include the mucopolysaccharidoses, mucolipidoses, oligosaccharidoses, Pompe disease, Gaucher disease, Fabry disease, the Niemann-Pick disorders, and neuronal ceroid lipofuscinoses. This review summarizes the main clinical features, diagnosis, and management of LSDs with an emphasis on those for which treatment is available.

Lysosomal storage disease overview

The lysosomal storage diseases (LSDs) are a group of inherited metabolic disorders that are caused for the most part by enzyme deficiencies within the lysosome resulting in accumulation of undegraded substrate. This storage process leads to a broad spectrum of clinical manifestations depending on the specific substrate and site of accumulation. Examples of LSDs include the mucopolysaccharidoses, mucolipidoses, oligosaccharidoses, Pompe disease, Gaucher disease, Fabry disease, the Niemann-Pick disorders, and neuronal ceroid lipofuscinoses. This review summarizes the main clinical features, diagnosis, and management of LSDs with an emphasis on those for which treatment is available.

A case series of hereditary cerebellar ataxias in a highly consanguineous population from Northeast Brazil

BACKGROUND

There are few studies reporting characteristics of patients with cerebellar ataxias in the Brazilian population. The aim of this study was to provide a detailed neurological description of patients with hereditary ataxia followed by a neurology outpatient service in Brazil.

METHODS

Neurological and clinical evaluation of patients with hereditary ataxia was performed at a neurology service outpatient clinic of a hospital in Northeast Brazil between October 2013 and January 2015.

RESULTS

A total of 47 patients had ataxia as the main symptom. A high prevalence of consanguinity was found in the population studied (40.4%). Mean age was 38.4 ± 15.3 years, mean age at disease onset was 25.6 ± 17.3 years, mean disease duration was 12.8 ± 9.7 years, and mean score on the Scale for the Assessment and Rating of Ataxia (SARA) was 18.4 ± 7.7. Patients with recessive pattern of inheritance were younger, had earlier age at disease onset and greater severity of ataxia, measured by the SARA. Diagnosis was confirmed by molecular analysis, laboratory exams or biopsy in 42.56% (n = 20) of these patients. The most prevalent diseases were: Friedreich's ataxia in 35% (n = 7), Niemann-Pick type C (NPC) in 15% (n = 3), and ataxia with oculomotor apraxia type 2 in 15% (n = 3).

CONCLUSIONS

In contrast with other studies, our prevalence of recessive ataxias was much higher than that of dominant ataxias. These findings might be explained by the high number of patients living in rural areas with a higher rate of consanguineous marriages, absence of a dominant ataxia founder effect or difficult access to healthcare system.

Psychiatric Disorders Secondary to Neurometabolic Disorders

Some diseases secondary to inborn errors of metabolism are associated with psychiatric disorders or minor neurological symptoms. The existence of some cases with exclusively psychiatric symptoms represents a diagnostic and therapeutic challenge. The aim of this article is to describe seven treatable neurometabolic disorders that should be taken into account in the psychiatric consultation as they manifest with psychiatric symptoms that mask the organic origin of the disorder. Homocysteine metabolism and urea cycle disorders, Wilson's disease, Niemann-Pick disease Type C, acute porphyria and cerebrotendinous xanthomatosis are described. Following an analysis of the literature, a list of psychiatric symptoms associated with these disorders are proposed, ranging from insidious changes in affective state and thought to atypical symptoms such as visual hallucinations, as well as paradoxical effects of antipsychotics or behavioural disorders in children and adolescents associated with loss of autonomy. The most frequently associated neurological signs, such as alterations in the state of consciousness, motor behaviour and balance disorders, catatonia or progressive cognitive deficit are also listed. Emphasis is placed on the importance of considering resistance to antipsychotic treatment as a warning sign to suspect organicity, as well as the significant improvement in psychiatric impairment when effective and early treatment is established.

Phenotypic variability of Niemann-Pick disease type C including a case with clinically pure schizophrenia: a case report

Background

Niemann-Pick disease type C (NPC) is a lysosomal storage disorder with severe prognosis. Disease-specific therapy is crucial to prevent disease progression; however, diagnosing NPC is quite difficult because of remarkably variable clinical presentations. The NPC Suspicion Index (NPC-SI) was developed to overcome this problem. Identifying preclinical cases is important for prevention and therapy. Here, we report three newly diagnosed NPC cases, one typical juvenile-onset case and the cases of two sisters with symptoms neurologically/psychiatrically indistinguishable from dystonia and schizophrenia, respectively.

Case presentation

In Case 1, a 25-year-old man presented with a 14-year history of intellectual disability, clumsiness, spastic ataxia, dysphagia, and frequent falls. Neurological examination revealed vertical supranuclear gaze palsy and involuntary movements. Ultrasonography revealed mild splenomegaly, and filipin staining of skin fibroblasts was positive with a variant staining pattern. NPC1 gene analysis showed compound heterozygous mutations, including c.1421C > T (p.P474L), a known causative mutation, and c.3722 T > C (p.L1241S), a new mutation. In Case 2, a 28-year-old woman, the proband, who had marked splenomegaly in her childhood, survived well, contrary to the expected severe prognosis of infantile NPC. She had minor neuropsychiatric symptoms including auditory hallucinations, nocturnal urination, and sleep paralysis. At the age of 28 years, she presented with a 1-year history of orofacial and oromandibular painful dystonia. The patient’s 35-year-old sister (Case 3) was diagnosed with schizophrenia. In both cases, filipin staining of skin fibroblasts was positive with variant staining patterns, as well as elevated levels of urinary bile acids. NPC1 gene analysis showed compound heterozygous mutations including c.3011C > T (p.S1004 L), a known causative mutation, and c.160_161insG (p.D54GfsX4), a new mutation. Their mother, who was under therapy with modafinil for narcolepsy, shared the latter mutation.

Conclusions

Marked clinical variability was observed in our three cases. NPC could masquerade as a pure neuropsychiatric disorder such as dystonia or schizophrenia. Abdominal ultrasonography, history evaluation, and neurological examination were quite important in the diagnostic process.

Niemann-Pick disease type C in the newborn period: a single-center experience

Niemann-Pick disease type C (NPC) is a neurovisceral lysosomal storage disorder with a great variation in clinical spectrum and age at presentation. Clinical features of 10 NPC patients who presented in the newborn period between 1993 and 2015 at our center were retrospectively analyzed. Males and females were equally distributed; there was a history of parental consanguinity (n = 8) and first-degree relative with NPC (n = 3). Patients were symptomatic between 1 and 10 days (mean 3.6 ± 2.6 days). Age at diagnosis was between 1 and 30 days (mean 14.6 ± 13.3 days). Laboratory work-up included bone marrow aspiration (n = 8) and/or filipin staining (n = 4). Confirmation was done by molecular analysis, indicating NPC1 (n = 8) and NPC2 (n = 2) mutations. All patients had neonatal cholestasis and hepatosplenomegaly. Pulmonary involvement (n = 9) and fetal ascites (n = 2) were additional accompanying features. All but one died due to pulmonary complications (n = 6) and liver insufficiency (n = 3) between 1.5 and 36 months of age (mean 8.1 ± 10.8 months). Currently, one patient is alive at the age of 11 months without any neurological deficit.

CONCLUSIONS

Neonatal presentation is a rare form of NPC with exclusively visceral involvement in the newborn period and poor prognosis leading to premature death due to pulmonary complications and liver failure. What is known: • Neonatal presentation is a rare form of NPC with exclusively visceral involvement in the newborn period and poor prognosis leading to premature death. • Progressive liver disease is the most common cause of death among neonatal-onset NPC patients. What is new: • Natural course of neonatal-onset NPC may show variations. • Pulmonary involvement should be considered as an important cause of death in neonatal-onset cases, and appropriate precautions should be taken to prevent complications of respiratory insufficiency and airway infections.

Differences in Niemann-Pick disease Type C symptomatology observed in patients of different ages

BACKGROUND

Niemann-Pick disease Type C (NP-C) is a genetic lipid storage disorder characterised by progressive neurovisceral symptomatology. Typically, disease progression is more pronounced in patients with early onset of neurological symptoms. Heterogeneous clinical presentation may hinder disease recognition and lead to delays in diagnosis. Here we describe the prevalence of signs and symptoms observed in patients with NP-C and analyse the relationship between these symptoms in different age groups.

METHODS

The combined patient cohort used in the analyses comprised NP-C cases (n=164) and controls (n=135) aged 0 to 60years from two previously published cohorts; a cohort of all ages from which patients ≤4years of age were excluded and a cohort with early-onset NP-C and age-matched controls. The analysis of relationships between different signs and symptoms was performed for both NP-C cases and controls in two sub-groups, ≤4 and >4years of age, using cluster analyses. The threshold of 4years of age was selected to reflect the minimum age cut-off for satisfactory discriminatory power of the original NP-C SI. To assess the prevalence of individual signs and symptoms at age of diagnosis, patients were categorised by age into 5-year sub-groups, and prevalence values estimated for each sign and symptom of NP-C.

RESULTS

Two main clusters of symptoms were clearly defined for NP-C cases in each age sub-group, whereas clusters were not as clearly defined for controls. For NP-C cases ≤4years of age, one cluster comprised exclusively visceral symptoms; the second cluster combined all other signs and symptoms in this age group. For NP-C cases >4years of age, each cluster contained a mixture of visceral, neurological and psychiatric items. Prevalence estimations showed that visceral symptoms (e.g. isolated unexplained splenomegaly) were most common in NP-C cases ≤4years of age. Neurological symptoms were generally more common in NP-C cases >4years of age than in younger patients, with the exception of hypotonia and delayed developmental milestones.

CONCLUSIONS

These analyses provide a comprehensive overview of symptomatology observed in a large combined cohort of patients with NP-C and controls across a wide range of ages. The results largely reflect observations from clinical practice and support the importance of multi-disciplinary approaches for identification of patients with NP-C, taking into account age-specific manifestations and their possible correlations.

Diagnostic tests for Niemann-Pick disease type C (NP-C): A critical review

Niemann-Pick disease type C (NP-C) is a neurovisceral lysosomal cholesterol trafficking and lipid storage disorder caused by mutations in one of the two genes, NPC1 or NPC2. Diagnosis has often been a difficult task, due to the wide range in age of onset of NP-C and clinical presentation of the disease, combined with the complexity of the cell biology (filipin) laboratory testing, even in combination with genetic testing. This has led to substantial delays in diagnosis, largely depending on the access to specialist centres and the level of knowledge about NP-C of the physician in the area. In recent years, advances in mass spectrometry has allowed identification of several sensitive plasma biomarkers elevated in NP-C (e.g. cholestane-3β,5α,6β-triol, lysosphingomyelin isoforms and bile acid metabolites), which, together with the concomitant progress in molecular genetic technology, have greatly impacted the strategy of laboratory testing. Specificity of the biomarkers is currently under investigation and other pathologies are being found to also result in elevations. Molecular genetic testing also has its limitations, notably with unidentified mutations and the classification of new variants. This review is intended to increase awareness on the currently available approaches to laboratory diagnosis of NP-C, to provide an up to date, comprehensive and critical evaluation of the various techniques (cell biology, biochemical biomarkers and molecular genetics), and to briefly discuss ongoing/future developments. The use of current tests in proper combination enables a rapid and correct diagnosis in a large majority of cases. However, even with recent progress, definitive diagnosis remains challenging in some patients, for whom combined genetic/biochemical/cytochemical markers do not provide a clear answer. Expertise and reference laboratories thus remain essential, and further work is still required to fulfill unmet needs.

A Suspicion Index to aid screening of early-onset Niemann-Pick disease Type C (NP-C)

BACKGROUND

Niemann-Pick disease Type C (NP-C) is difficult to diagnose due to heterogeneous and nonspecific clinical presentation. The NP-C Suspicion Index (SI) was developed to identify patients with a high likelihood of NP-C; however, it was less reliable in patients aged <4 years.

METHODS

An early-onset NP-C SI was constructed following retrospective chart review of symptom presentation in 200 patients from nine centres comprised of 106 NP-C cases, 31 non-cases and 63 controls. Statistical analyses defined strength of association between symptoms and a diagnosis of NP-C and assigned risk prediction scores to each symptom.

RESULTS

Visceral symptoms were amongst the strongest predictors. Except for gelastic cataplexy and vertical supranuclear gaze palsy, central nervous system symptoms were not discriminatory in this population. Performance of the early-onset NP-C SI was superior versus the original NP-C SI in patients aged ≤4 years.

CONCLUSIONS

The early-onset NP-C SI can help physicians, especially those with limited knowledge of NP-C, to identify patients aged ≤4 years who warrant further investigation for NP-C.

Identifying Niemann-Pick type C in early-onset ataxia: two quick clinical screening tools

Niemann–Pick disease type C (NP-C) is a rare multisystemic lysosomal disorder which, albeit treatable, is still starkly underdiagnosed. As NP-C features early onset ataxia (EOA) in 85–90 % of cases, EOA presents a promising target group for undiagnosed NP-C patients. Here, we assessed the ability of the previously established NP-C suspicion index (SI) and a novel abbreviated ‘2/3 SI’ tool for rapid appraisal of suspected NP-C in unexplained EOA. This was a retrospective observational study comparing ‘NP-C EOA’ cases (EOA patients with confirmed NP-C) with non-NP-C EOA controls (EOA patients negative for NP-C gene mutations). NP-C risk prediction scores (RPS) from both the original and 2/3 SIs were calculated and their discriminatory performance evaluated. Among 133 patients (47 NP-C EOA cases; 86 non-NP-C EOA controls), moderate (40–69 points) and high (≥70 points) RPS were common based on original SI assessments in non-NP-C EOA controls [16 (19 %) and 8 (9 %), respectively], but scores ≥70 points were far more frequent [46 (98 %)] among NP-C EOA cases. RPS cut-off values provided 98 % sensitivity and 91 % specificity for NP-C at 70-point cut-off, and ROC analysis revealed an AUC of 0.982. Using the 2/3 SI, 90 % of NP-C EOA cases had scores of 2 or 3, and RPS analysis showed an AUC of 0.961. In conclusion, the NP-C SI and the new, quick-to-apply 2/3 SI distinguished well between NP-C and non-NP-C patients, even in EOA populations with high background levels of broadly NPC-compatible multisystemic disease features. While the original SI showed the greatest sensitivity, both tools reliably aided identification of patients with unexplained EOA who warranted further investigation for NP-C.

Diagnostic workup and management of patients with suspected Niemann-Pick type C disease

Niemann-Pick type C (NP-C) disease is a neurovisceral disorder caused by mutations in the NPC1 and NPC2 genes. It is characterized by lysosomal storage of a broad range of lipids as a result of abnormal intracellular lipid trafficking. Typically patients develop neurodegeneration; however, the speed of disease progression is variable. The exact functions of NPC1 and NPC2 proteins have not been determined and therefore the molecular pathophysiology of NP-C is still not clearly understood. Due to the disease's rarity and clinical heterogeneity, delays from symptom onset to diagnosis and treatment initiation are common. Current therapeutic approaches focus on multidisciplinary symptom control and deceleration (rather than reversal) of disease progression. Thus identification of cases at early stages of disease is particularly important. Recent advances in genetic and biochemical testing have resulted in the generation of relatively non-invasive, quick and cost-effective laboratory assays that are highly sensitive and specific and have the capacity to enhance the clinicians' ability to reach a diagnosis earlier. Miglustat is a compound recently licensed in many countries for the treatment of NP-C that has been shown to decelerate neurological regression, whereas many other promising drugs are currently being trialled in preclinical models or human studies. This review summarizes key clinical, genetic and biochemical features of NP-C, suggests a simple diagnostic investigation strategy and gives an overview of available therapeutic options as well as potential novel treatments currently under development.

Otorhinolaryngological, audiovestibular and swallowing manifestations of patients with Niemann-Pick disease Type C

OBJECTIVES

The aim of this study is to evaluate audiovestibular and swallowing impairment of patients with NPC.

METHODS

Audiovestibular and swallowing evaluation were performed on patients with Niemann-Pick disease type C (NPC) at Hacettepe University between 20013 and 2015 prospectively. Pure-tone audiometry (PTA), Auditory Brain stem response (ABR), Flexible endoscopic evaluation of swallowing (FEES) test and posturography were done. Hearing, swallowing and balance states were measured.

RESULTS

There were 16 patients (5 male and 11 female, with a median age of 6.5 years old). The most common ABR abnormalities observed were absent waves I and III (%70 absent I waves, %43.75 absent III waves). Twelve of sixteen patients (%75) had an ABR abnormality in at least one ear, of these, four patients had normal hearing and three of them had periferal hearing loss. 12 (75%) patients had complaint of postural imbalance. 11(69%) of patients had peripheral and one (6%) patient had central impairment. Nine of sixteen patients (56.25%) show some degree of dysphagia (either penetration or aspiration). Two patients (12.5%) showed aspiration both liquid and viscous nutrition. Three patients (18.75%) showed aspiration primarily in liquids and two of them had penetration with viscous nutrition. Three patients (18.75%) had penetration with no aspiration neither liquid nor viscous nutrition (PEN-ASP score was 3, 3, 5, respectively).

CONCLUSION

There is no curative treatment for this devastating and fatal disorder and hearing impairment, balance and swallowing disorders can be seen especially late onset form of disease.

Observational cohort study of the natural history of Niemann-Pick disease type C in the UK: a 5-year update from the UK clinical database

BACKGROUND

Niemann-Pick disease type C (NP-C) is a rare neurovisceral lipid storage disorder characterised by progressive, disabling neurological symptoms and premature death in most patients. During the last decade, national cohort studies have accrued a great deal of data on the symptomatology and natural history of NP-C.

METHODS

In an observational cohort study, we present a substantial update based on the clinical presentation and follow-up of all known UK-based patients with a confirmed diagnosis of NP-C who have been tracked on an electronic database at the Department of Genetic Medicine, University of Manchester, UK. Patients were stratified according to accepted age-at-neurological-onset categories. Data on patients' clinical signs and symptoms, medical history and genetic studies are summarised using descriptive methods.

RESULTS

A total of 146 patients with NP-C were included, representing the full known UK NP-C cohort, as observed from database information between 1999 and the end of 2011: 72 patients (49 %) were alive at the end of the observation period. Among a total of 116 patients (79 %) who possessed at least one identified, disease-causing NP-C gene mutation, 114 (98 %) had NPC1 and two (2 %) had NPC2 mutations. Overall, 53/194 (27 %) identified mutations were novel. Six patients (4 %) had an early, non-neurological neonatal onset form of NP-C. The numbers (%) of patients with accepted age-at-neurological onset forms were: 8 (5 %) early-infantile onset, 51 (35 %) late-infantile onset, 42 (29 %) juvenile onset, and 25 (17 %) adolescent/adult onset. Fourteen patients diagnosed based on visceral symptoms and/or sibling history, confirmed in most cases by genetic analysis, did not have any neurological manifestations at last follow up (11 patients with mean [SD] age at last follow up 2.5 [1.8] years: 3 with mean [SD] age at death 20.8 [15.9] years). A total of 51 patients (35 %) received miglustat therapy. The mean (SD) overall treatment duration up to the end of the observation period was 2.6 (2.3) years.

CONCLUSIONS

This UK cohort is the largest national NP-C cohort reported to date, and confirms the wide phenotypic variability of the disease, as reported in other countries. Further analyses are required to assess the impact of miglustat therapy on neurological disease progression.

Recent advances in the diagnosis and treatment of niemann-pick disease type C in children: a guide to early diagnosis for the general pediatrician

Niemann-Pick disease (NP-C) is a lysosomal storage disease in which impaired intracellular lipid transport leads to accumulation of cholesterol and glycosphingolipids in various neurovisceral tissues. It is an autosomal recessive disorder, caused by mutations in the NPC1 or NPC2 genes. The clinical spectrum is grouped by the age of onset and onset of neurological manifestation: pre/perinatal; early infantile; late infantile; and juvenile periods. The NP-C Suspicion Index (SI) screening tool was developed to identify suspected patients with this disease. It is especially good at recognizing the disease in patients older than four years of age. Biochemical tests involving genetic markers and Filipin staining of skin fibroblast are being employed to assist diagnosis. Therapy is mostly supportive and since 2009, the first specific therapy approved for use was Miglustat (Zavesca) aimed at stabilizing the rate of progression of neurological manifestation. The prognosis correlates with age at onset of neurological signs; patients with early onset form progress faster. The NP-C disease has heterogeneous neurovisceral manifestations. A SI is a screening tool that helps in diagnostic process. Filipin staining test is a specific biomarker diagnostic test. Miglustat is the first disease-specific therapy.

Miglustat: a review of its use in Niemann-Pick disease type C

Miglustat (Zavesca®, Brazaves®), a small iminosugar molecule that reversibly inhibits glycosphingolipid synthesis, is the only disease-specific drug approved for the treatment of progressive neurological manifestations of Niemann-Pick disease type C (NP-C) in adult and paediatric patients. NP-C is a rare, autosomal-recessive lipid storage disorder characterized by impaired intracellular lipid trafficking and progressive neurological symptoms leading to premature death. In a randomized clinical trial, long-term extension studies and a retrospective observational cohort study, treatment with oral miglustat stabilized key neurological manifestations of NP-C (including horizontal saccadic eye movement peak velocity, ambulation, manipulation, language and swallowing) in paediatric and adult patients with the disease. The therapeutic effects of miglustat in stabilizing or slowing disease progression have been confirmed in other reports in the clinical experience setting. The primary tolerability issues associated with miglustat are mild to moderate gastrointestinal effects (e.g. diarrhoea, flatulence and abdominal pain/discomfort) and weight loss, which usually occur during initial therapy and are generally manageable. In the absence of a cure, miglustat is a valuable agent to reduce the progression of clinically relevant neurological symptoms in paediatric and adult patients with NP-C, which is considered a significant achievement in the treatment of this disease.

Complex lipid trafficking in Niemann-Pick disease type C

Niemann-Pick disease type C (NPC) is an atypical lysosomal storage disease resulting from mutations in one of two genes, either NPC1 or NPC2. Although a neurovisceral disorder, it is above all a neurodegenerative disease in the vast majority of patients. Not an enzyme deficiency, it is currently conceived as a lipid trafficking disorder. Impaired egress of cholesterol from the late endosomal/lysosomal (LE/L) compartment is a specific and key element of the pathogenesis, but other lipids, more specially sphingolipids, are also involved, and there are indications for further abnormalities. The full function of the NPC1 and NPC2 proteins is still unclear. This review provides a reappraisal of lipid storage and lysosomal enzymes activities in tissues/cells from NPC patients and animal models. It summarizes the current knowledge on the NPC1 and NPC2 proteins and their function in transport of cholesterol within the late endosomal-lysosomal compartment, with emphasis on differences between systemic organs and the brain; it also discusses regulation by membrane lipids of the NPC2-mediated cholesterol trafficking, interplay between cholesterol and sphingomyelin, the metabolic origin of glycosphingolipids stored in brain, and the putative role of free sphingoid bases in pathogenesis. Brief mention is finally made of diseases affecting other genes that were very recently shown to impact the "NPC pathway".

Early co-occurrence of a neurologic-psychiatric disease pattern in Niemann-Pick type C disease: a retrospective Swiss cohort study

Background

Niemann-Pick disease type C (NP-C) is a rare autosomal recessive disorder of lysosomal cholesterol transport. The objective of this retrospective cohort study was to critically analyze the onset and time course of symptoms, and the clinical diagnostic work-up in the Swiss NP-C cohort.

Methods

Clinical, biochemical and genetic data were assessed for 14 patients derived from 9 families diagnosed with NP-C between 1994 and 2013. We retrospectively evaluated diagnostic delays and period prevalence rates for neurological, psychiatric and visceral symptoms associated with NP-C disease. The NP-C suspicion index was calculated for the time of neurological disease onset and the time of diagnosis.

Results

The shortest median diagnostic delay was noted for vertical supranuclear gaze palsy (2y). Ataxia, dysarthria, dysphagia, spasticity, cataplexy, seizures and cognitive decline displayed similar median diagnostic delays (4–5y). The longest median diagnostic delay was associated with hepatosplenomegaly (15y). Highest period prevalence rates were noted for ataxia, dysarthria, vertical supranuclear gaze palsy and cognitive decline. The NP-C suspicion index revealed a median score of 81 points in nine patients at the time of neurological disease onset which is highly suspicious for NP-C disease. At the time of diagnosis, the score increased to 206 points.

Conclusion

A neurologic-psychiatric disease pattern represents the most characteristic clinical manifestation of NP-C and occurs early in the disease course. Visceral manifestation such as isolated hepatosplenomegaly often fails recognition and thus highlights the importance of a work-up for lysosomal storage disorders. The NP-C suspicion index emphasizes the importance of a multisystem evaluation, but seems to be weak in monosymptomatic and infantile NP-C patients.

Electronic supplementary material

The online version of this article (doi:10.1186/s13023-014-0176-7) contains supplementary material, which is available to authorized users.

Psychosis in an adolescent girl: a common manifestation in Niemann-Pick Type C disease

Niemann-Pick disease type C (NP-C) is a rare autosomal-recessively inherited lysosomal storage disorder. It is caused by mutations in the NPC1 (95%) or NPC2 gene. It is a progressive and highly heterogeneous disease, characterized by the presentation of visceral, neurological, and psychiatric symptoms. Apart from the patients that die early from organic failure, most of the patients with juvenile and adolescent/adult onset of the disease, develop neurological and psychiatric symptoms. In some cases psychiatric signs, mostly psychosis, can be the first sign of the disease. A delay in diagnosis is often seen. By describing the case of a 16-year old girl, we would like to highlight current opinion about NP-C disease and resume recent findings on the clinical presentation, diagnosis and treatment. We focus on the psychiatric signs, and most important the specific combinations that are typical for the disease. There is no curative treatment for NP-C. Miglustat is used to modify neurological signs in NP-C.

Niemann-Pick disease type C symptomatology: an expert-based clinical description

Niemann-Pick disease type C (NP-C) is a rare, progressive, irreversible disease leading to disabling neurological manifestations and premature death. The estimated disease incidence is 1:120,000 live births, but this likely represents an underestimate, as the disease may be under-diagnosed due to its highly heterogeneous presentation. NP-C is characterised by visceral, neurological and psychiatric manifestations that are not specific to the disease and that can be found in other conditions. The aim of this review is to provide non-specialists with an expert-based, detailed description of NP-C signs and symptoms, including how they present in patients and how they can be assessed. Early disease detection should rely on seeking a combination of signs and symptoms, rather than isolated findings. Examples of combinations which are strongly suggestive of NP-C include: splenomegaly and vertical supranuclear gaze palsy (VSGP); splenomegaly and clumsiness; splenomegaly and schizophrenia-like psychosis; psychotic symptoms and cognitive decline; and ataxia with dystonia, dysarthria/dysphagia and cognitive decline. VSGP is a hallmark of NP-C and becomes highly specific of the disease when it occurs in combination with other manifestations (e.g. splenomegaly, ataxia). In young infants (<2 years), abnormal saccades may first manifest as slowing and shortening of upward saccades, long before gaze palsy onset. While visceral manifestations tend to predominate during the perinatal and infantile period (2 months-6 years of age), neurological and psychiatric involvement is more prominent during the juvenile/adult period (>6 years of age). Psychosis in NP-C is atypical and variably responsive to treatment. Progressive cognitive decline, which always occurs in patients with NP-C, manifests as memory and executive impairment in juvenile/adult patients. Disease prognosis mainly correlates with the age at onset of the neurological signs, with early-onset forms progressing faster. Therefore, a detailed and descriptive picture of NP-C signs and symptoms may help improve disease detection and early diagnosis, so that therapy with miglustat (Zavesca(®)), the only available treatment approved to date, can be started as soon as neurological symptoms appear, in order to slow disease progression.