Development of a Suspicion Index to aid diagnosis of Niemann-Pick disease type C

Department of Paediatrics, Academic Medical Center, University of Amsterdam, Amsterdam, The Netherlands.
Neurology (Impact Factor: 8.3). 04/2012; 78(20):1560-7. DOI: 10.1212/WNL.0b013e3182563b82
Source: PubMed

ABSTRACT Niemann-Pick disease type C (NP-C) is a rare, autosomal recessive lysosomal lipid storage disorder that is invariably fatal. NP-C diagnosis can be delayed for years due to heterogeneous presentation; adult-onset NP-C can be particularly difficult to diagnose. We developed a Suspicion Index tool, ranking specific symptoms within and across domains, including family members who have NP-C, to provide a risk prediction score to identify patients who should undergo testing for NP-C.
A retrospective chart review was performed in 5 centers in Europe and 2 in Australia (n = 216). Three patient types were selected: classic or variant filipin staining NP-C cases (n = 71), NP-C noncases (confirmed negative by filipin staining; n = 64), or controls with at least 1 characteristic symptom of NP-C (n = 81). NP-C signs and symptoms were categorized into visceral, neurologic, or psychiatric domains. Logistic regression was performed on individual signs and symptoms within and across domains, and regression coefficients were used to develop prediction scores for NP-C. Internal validation was performed with the bootstrap resampling method.
The Suspicion Index tool has good discriminatory performance with cutpoints for grading suspicion of NP-C. Neonatal jaundice/cholestasis, splenomegaly, vertical supranuclear gaze palsy, cataplexy, and cognitive decline/dementia were strong predictors of NP-C, as well as symptoms occurring in multiple domains in individual patients, and also parents/siblings or cousins with NP-C.
The Suspicion Index tool is a screening tool that can help identify patients who may warrant further investigation for NP-C. A score ≥70 indicates that patients should be referred for testing for NP-C.

Download full-text


Available from: Christian J Hendriksz, Jul 06, 2015
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: Niemann-Pick type C disease (NPC) is a rare lysosomal disease with a protean presentation, ranging from a fatal neonatal course with visceromegaly to an adult presentation with only neurological or psychiatric symptomatology. In this report we describe the genetic and clinical characteristics of 3 Mexican patients from different families with juvenile presentation of NPC. Clinical examination, imaging of central nervous and gastrointestinal system, and EEG were performed. Genetic studies include sequencing and deletion/duplication analysis of NPC1 and NPC2 genes. All patients presented with cognitive impairment, ataxia, and supranuclear vertical gaze palsy; one case had gelastic cataplexy. Also they developed epilepsy and cortical atrophy and two patients had thinning of corpus callosum. The 3 patients were compound heterozygotes for NPC1 sequence variants, including 5 missense and 1 nonsense mutations: p.P1007A and p.F1087L in Case 1; p.Q921P and p.G992R in Case 2; and p.R348 * and p.V1165M in case 3. Mexican patients with juvenile NPC presented with a variable clinical phenotype and compound heterozygosity. This suggests a relative high frequency of mutation carriers as it is reported for European population. Consequently, clinicians should consider NPC as a diagnosis possibility in any adolescent or young adult patient with juvenile dementia and/or ataxia, even in absence of gelastic cataplexy and supranuclear vertical gaze palsy.
    10/2014; 2014:785890. DOI:10.1155/2014/785890
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: The Suspicion Index (SI) screening tool was developed to identify patients suspected of having Niemann-Pick disease type C (NP-C). The SI provides a risk prediction score (RPS) based on NP-C manifestations within and across domains (visceral, neurological, and psychiatric). The aim of these subanalyses was to further examine the discriminatory power of the SI by age and manifestation-associations by NP-C suspicion-level and leading manifestations. The original retrospectively collected data were split into three patient age groups, where NP-C-positive cases were >16 years (n = 30), 4-16 years (n = 18), and <4 years (n = 23), and patients' RPS were analyzed by logistic regression. Co-occurrence of manifestations within groups of suspicion level (low, medium, high) and leading manifestations (presence/absence of ataxia, cognitive decline, psychosis, and splenomegaly) were analyzed descriptively. NP-C-positive cases versus controls showed strong discriminatory power of RPS. Area under the receiver operating characteristic curve was 0.964 (>16 years) and 0.981 (4-16 years) but weaker 0.562 for infants (<4 years). Patients with RPS <70 were characterized by a lack of psychiatric manifestations and low levels of neurological involvement, suggestive of a preneurological phase of the disease. In patients >4 years, prominent leading manifestation-associations were ataxia with dystonia, dysarthria/dysphagia, and cognitive decline. Psychosis was associated with dysarthria/dysphagia but also with cognitive decline and treatment-resistant psychiatric symptoms. The SI tool maintains strong discriminatory power in patients >4 years but is not as useful for infants <4 years. The SI is also informative regarding the association and co-occurrence of manifestations in patients with NP-C.
    Journal of Inherited Metabolic Disease 06/2013; 37(1). DOI:10.1007/s10545-013-9626-y · 4.14 Impact Factor
  • [Show abstract] [Hide abstract]
    ABSTRACT: In this issue of Neurology®, Wijburg et al.(1) introduce a Suspicion Index to be used at the bedside for diagnosing Niemann-Pick disease type C (NP-C). Are such tools likely to be integrated into clinical practice, and if so, how will such integration come about?
    Neurology 04/2012; 78(20):1546-7. DOI:10.1212/WNL.0b013e3182563c36 · 8.30 Impact Factor