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: 8.29). 04/2012; 78(20):1560-7. DOI: 10.1212/WNL.0b013e3182563b82
Source: PubMed


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.

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Available from: Christian J Hendriksz
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    • "The studied sister does not carry any of the mutations and is asymptomatic. Suspicion index for NPC [9], performed retrospectively, scored 227 points. The patient initiated miglustat late in progression of NPC disease with a modified functional disability scale score of 17 points [10] by a short period (less than 6 months). "
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    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.
    Full-text · Article · Oct 2014
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    • "Prolonged unexplained neonatal jaundice or cholestasis and isolated unexplained splenomegaly (historical and/or current) with/without hepatomegaly are the strongest visceral indicators for NP-C [6]. As in our patient, patients often show a history of neonatal jaundice or splenomegaly during infancy [2,5,9]. "
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    ABSTRACT: 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.
    Full-text · Article · Jul 2014 · Child and Adolescent Psychiatry and Mental Health
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    • "Since 7-KC assay could be performed in a high throughput manner in our lab, we did not calculate score of the suspicion index [31] when recruiting subjects to this study to avoid missing atypical patients. We identified 12 individuals with high levels of plasma 7-KC, who were then confirmed to be NP-C by genetic testing, indicating a strong specific correlation between elevated 7-KC and NP-C. "
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    ABSTRACT: Background It has been reported that oxidation product of cholesterol, 7-ketocholesterol, increases in plasma of patients with NP-C. Previously, we established a rapid test to determine the plasma 7-ketocholesterol level and found it elevated significantly in patients with acid sphingomyelinase deficient NPD and NP-C disease. Methods Individuals randomly referred to our outpatient clinics in the past two years for hepatosplenomegaly or isolated splenomegaly, who have been excluded as acid sphingomyelinase deficient NPD or Gaucher disease, and individuals with newborn cholestasis, psychomotor regression/retardation, were screened for plasma 7-ketocholesterol level. Individuals with high 7-ketocholesterol level were then analyzed for NPC1 and NPC2 gene mutation to confirm the accuracy of NP-C diagnosis. Results By screening the plasma 7-ketocholesterol of suspect individuals, 12 out of 302 (4%) had shown remarkable high levels compared with reference. All these twelve individuals were subsequently confirmed to be NP-C by DNA analysis of NPC1 and NPC2 genes, with the early infantile form (n = 7), the late infantile form (n = 1), the juvenile form (n = 1) and the adult form (n = 1). Furthermore, two NP-C patients without observable neuropsychiatric disability were picked up through this procedure. Only one patient had NP-C due to NPC2 gene mutations, with the rest due to NPC1 gene mutations. We found that in NP-C patients AST was usually mildly elevated and ALT was in a normal range when jaundice was not present. In total, 22 mutant alleles were identified in the NPC1 gene, including six novel small deletions/insertions, e.g., c.416_417insC, c.1030delT, c.1800delC, c.2230_2231delGT, c.2302_2303insG, and c.2795dupA; seven novel exonic point mutations, c.1502A>T (p.D501V), c.1553G>A (p.R518Q), c.1832A>G (p.D611G), c.2054T>C (p.I685T), c.2128C>T(p.Q710X), c.2177G>C (p.R726T), c.2366G>A (p.R789H), and one novel intronic mutation c.2912-3C>G. Small deletions/insertions constituted nearly half of the mutant alleles (10/22, 45%), indicating a unique mutation spectrum in this cohort of Chinese NP-C patients. Conclusion Our data confirm in a clinical setting that screening plasma 7-ketocholesterol is an efficient and practical diagnostic tool to identify NP-C patients from suspect individuals. Patients without neuropsychological involvement could also be identified by this method therefore allowing an opportunity for earlier treatment.
    Full-text · Article · Jun 2014 · Orphanet Journal of Rare Diseases
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