Niemann–Pick disease type C (NP-C) is a rare inherited neurovisceral disease caused by mutations in either the NPC1 (in 95% of cases) or the NPC2 gene (in around 5% of cases), which lead to impaired ...intracellular lipid trafficking and accumulation of cholesterol and glycosphingolipids in the brain and other tissues. Characteristic neurological manifestations of NP-C include saccadic eye movement (SEM) abnormalities or vertical supranuclear gaze palsy (VSGP), cerebellar signs (ataxia, dystonia/dysmetria, dysarthria and dysphagia) and gelastic cataplexy. Epileptic seizures are also common in affected patients. Typically, neurological disease onset occurs during childhood, although an increasing number of cases are being detected and diagnosed during adulthood based on late-onset neurological signs and psychiatric manifestations. Categorization of patients according to age at onset of neurological manifestations (i.e. early-infantile, late-infantile, juvenile and adolescent/adult-onset) can be useful for the evaluation of disease course and treatment responses. The first international guidelines for the clinical management of NP-C in children and adults were published in 2009. Since that time a significant amount of data regarding the epidemiology, detection/diagnosis, and treatment of NP-C has been published. Here, we report points of consensus among experts in the diagnosis and treatment of NP-C based on a follow-up meeting in Paris, France in September 2011. This article serves as an update to the original guidelines providing, among other things, further information on detection/diagnostic methods, potential new methods of monitoring disease progression, and therapy. Treatment goals and the application of disease-specific therapy with miglustat are also re-evaluated.
► Niemann–Pick disease type C (NP-C) is a rare inherited neurovisceral disease. ► The first international guidelines for managing NP-C were published in 2009. ► This article serves as an update to the original guidelines.
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.
•NP-C: heterogenous neurovisceral lipid storage disorder; mutations in NPC1 or NPC2•Neonatal cholestasis, splenomegaly, ataxia, vertical gaze palsy, neurodegeneration•‘Filipin test’ evaluates abnormalities of lysosomal cholesterol trafficking/egress.•Several newly developed plasma biomarkers allow inexpensive first screening tests.•Wide accessibility of biomarker analysis and gene sequencing will improve diagnosis.
Morquio A syndrome is a rare, autosomal recessive, lysosomal storage disorder caused by a deficiency in the enzyme N-acetylgalactosamine-6-sulfatase (GALNS). In 2014, the use of recombinant human ...GALNS, elosulfase alfa, was approved in the European Union, Canada, the United States, Australia, and Brazil for the treatment of Morquio A syndrome. Elosulfase alfa is administered intravenously once-weekly at a dose of 2.0 mg/kg. Areas covered: This is a review of the efficacy, safety and tolerability, pharmacokinetics and pharmacodynamics, and other outcomes of elosulfase alfa treatment of patients with Morquio A. A discussion of other treatment considerations, limitations, and future directions in the use of elosulfase alfa is provided. Expert commentary: Pharmacokinetic studies outside of clinical trials and in 'real-world' clinical settings need to be performed. We cannot currently predict which patient is going to respond well to enzyme replacement therapy; thus, all patients should be given the option to receive treatment for at least 12 months. Additionally, accurate biomarkers for evaluating disease state and drug responsiveness would greatly aid in the treatment of patients with Morquio A. In addition, improved and innovative daily lifestyle measures are greatly needed to adequately measure clinical response and true impact on quality of life.
Urea cycle disorders (UCD) are a group of rare inherited metabolic conditions of amino acid catabolism caused by an enzyme deficiency within the hepatic ammonia detoxification pathway. The ...presentation of these disorders ranges from life‐threatening intoxication in the neonate to asymptomatic status in adults. Late‐onset UCDs can present for the first time in adulthood and may mimic other causes of acute confusion or psychiatric diseases, and are often associated with neurological symptoms. Late‐onset UCDs may become apparent during periods of metabolic stress such as rapid weight loss, gastric bypass surgery, chronic starvation or the postpartum period. Early diagnosis is critical for effective treatment and to prevent long‐term complications of hyperammonemia. The challenges of management of adults include for example: (a) poor compliance to dietary and medical treatment which can result in recurrent hospital admissions; (b) severe neurological dysfunction; (c) the management of pregnancy and the postpartum period; and (d) access to multidisciplinary care peri‐operatively. In this review, we highlight a number of challenges in the diagnosis and management of adult patient with late‐onset UCDs and suggest a systematic management approach.
Approximately two-thirds of patients with the lysosomal storage disease mucopolysaccharidosis II have progressive cognitive impairment. Intravenous (i.v.) enzyme replacement therapy does not affect ...cognitive impairment because recombinant iduronate-2-sulfatase (idursulfase) does not penetrate the blood–brain barrier at therapeutic concentrations. We examined the safety of idursulfase formulated for intrathecal administration (idursulfase-IT) via intrathecal drug delivery device (IDDD). A secondary endpoint was change in concentration of glycosaminoglycans in cerebrospinal fluid.
Sixteen cognitively impaired males with mucopolysaccharidosis II who were previously treated with weekly i.v. idursulfase 0.5 mg/kg for ≥6 months were enrolled. Patients were randomized to no treatment or 10-mg, 30-mg, or 1-mg idursulfase-IT monthly for 6 months (four patients per group) while continuing i.v. idursulfase weekly.
No serious adverse events related to idursulfase-IT were observed. Surgical revision/removal of the IDDD was required in 6 of 12 patients. Twelve total doses were administrated by lumbar puncture. Mean cerebrospinal fluid glycosaminoglycan concentration was reduced by approximately 90% in the 10-mg and 30-mg groups and approximately 80% in the 1-mg group after 6 months.
These preliminary data support further development of investigational idursulfase-IT in MPS II patients with the severe phenotype who have progressed only to a mild-to-moderate level of cognitive impairment.
Morquio A syndrome (or mucopolysaccharidosis IVa) is an ultra-rare multi-organ disease, resulting in significantly impaired functional capacity, mobility and quality of life (QoL).
This ...patient-reported outcomes survey evaluated the global burden of Morquio A among adults (≥18 years, N = 27) and children (7-17 years, N = 36), including the impact on mobility, QoL, pain and fatigue. QoL was assessed using the general Health-Related Quality of Life (HRQoL) questionnaire (the EuroQol EQ-5D-5L). Pain and pain interference with daily activities were assessed using the Brief Pain Inventory Short Form (BPI-SF) in adults and the Adolescent Pediatric Pain Tool (APPT) in children. Fatigue was assessed by questioning the patients on the number of evenings in a week they felt extremely tired.
The clinical data showed a wide heterogeneity in clinical manifestations between patients, with the majority of patients showing differing levels of endurance, short stature, bone and joint abnormalities, abnormal gait and eye problems. Mobility was considerably impaired: 44.4% of children and 85.2% of adult patients were using a wheelchair. High wheelchair reliance significantly reduced QoL. This was mainly driven by reduced scores in the Mobility, Self-care, and Usual Activity domains. The HRQoL utility values were 0.846, 0.582 and 0.057 respectively in adults not using a wheelchair, using a wheelchair only when needed and always using a wheelchair; values were 0.534, 0.664 and -0.180 respectively in children. Employed adult patients had a better HRQoL than unemployed patients (HRQoL utility value 0.640 vs. 0.275, respectively).64% of children and 74% of adult patients had joint pain; fatigue was reported by 69% of children and 63% of adults. Overall, increased mobility was associated with more severe and widespread pain and more fatigue.
The HRQoL of Morquio A patients is mainly driven by the ability to remain independently mobile without becoming wheelchair dependent. Their QoL reduces dramatically if they always have to use their wheelchair. Even a slightly better mobility (wheelchair use only when needed) greatly improves QoL. Maintenance of functional capacity and mobility paired with better pain management are likely to improve QoL.
Mitochondrial dysfunction is emerging as an important contributory factor to the pathophysiology of lysosomal storage disorders (LSDs). The cause of mitochondrial dysfunction in LSDs appears to be ...multifactorial, although impaired mitophagy and oxidative stress appear to be common inhibitory mechanisms shared amongst these heterogeneous disorders. Once impaired, dysfunctional mitochondria may impact upon the function of the lysosome by the generation of reactive oxygen species as well as depriving the lysosome of ATP which is required by the V-ATPase proton pump to maintain the acidity of the lumen. Given the reported evidence of mitochondrial dysfunction in LSDs together with the important symbiotic relationship between these two organelles, therapeutic strategies targeting both lysosome and mitochondrial dysfunction may be an important consideration in the treatment of LSDs. In this review we examine the putative mechanisms that may be responsible for mitochondrial dysfunction in reported LSDs which will be supplemented with morphological and clinical information.
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.
To estimate clinical progression and resource utilisation together with the associated costs of managing children and adults with LAL Deficiency, at a tertiary referral centre in the UK.
A ...retrospective chart review was undertaken of patients in the UK with a confirmed diagnosis of LAL Deficiency who were managed at a LAL Deficiency tertiary referral treatment centre. Patients' pathways, treatment patterns, health outcomes and resource use were quantified over differing lengths of time for each patient enabling the NHS cost of patient management in tertiary care to be estimated.
The study population comprised 19 patients of whom 58% were male. Mean age at the time of initial presentation was 15.5 years and the mean age at diagnosis was 18.0 years. 63%, 53% and 42% of patients had hepatomegaly, abnormal lipid storage and splenomegaly at a mean age of presentation of 17.8, 17.1 and 20.9 years, respectively. Over a period of 50 years there were a mean of 48.5 clinician visits and 3.4 hospital admissions per patient. The mean NHS cost of patient management at a LAL Deficiency tertiary referral treatment centre, spanning a period of over 50 years was £61,454 per patient.
This study provides important insights into a number of aspects of the disease that are difficult to ascertain from published case reports. Additionally, it provides the best estimate available of NHS resource use and costs with which to inform policy and budgetary decisions pertaining to managing this ultra-orphan disease.
PDF
