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Table 1 Comparison of NP-C with other, similar ultra-rare IEMs

From: Recommendations for patient screening in ultra-rare inherited metabolic diseases: what have we learned from Niemann-Pick disease type C?

  NP-C Tay-Sachs disease MEGDEL syndrome Krabbe disease Gaucher disease type 3
Biological and biomarker features
 Genes NPC1/NPC2 HEXA SERAC1 GALC GBA
 Cellular markers Filipin staining Filipin staining, phosphatidylglycerol 34:1/36:1 levels [68, 69]
 Fluid/enzymatic diagnostic biomarkers Plasma oxysterols, bile acids, and lysosphingolipids (e.g. Lyso-SM-509) Plasma lyso GM2 ganglioside; plasma HEXA activity Urine 3-MGA/3-MGC Plasma GALC activity Plasma glucocerebrosidase activity, lyso-GB1
 Clinical manifestations Adult ataxia, VSSP, dystonia, myoclonus, dysphagia, dysarthria, cataplexy, psych. problems, visceral symptomsa SEM abnormalities, dysarthria, ataxia, dystonia, lower MND, myoclonus, epilepsy, psych. problems Hearing loss, dystonia, spasticity, dysarthria Vision/hearing loss, ataxia, dysmetria, spasticity Hepatosplenomegaly, thrombocytopenia, anaemia/fatigue, bone abnormalities, HSGP, ataxia, parkinsonism, epilepsy
Rarity and range of clinical features mandating a need for screening studies
 Ultra-rare Yes Yes Yes Yes Yes
 Variable phenotype, mainly neurological Yes Yes Yes Yes Yes
 Onset from infancy to adulthood Yes Yes Yes [69] Yes Yes
  1. aOther, non-specific neurological manifestations can also be present. GALC galactocerebrosidase, GBA beta-glucocerebrosidase, HEXA hexosaminidase A, HSGP horizontal supranuclear gaze palsy, MEGDEL 3-methylglutaconic aciduria with deafness, encephalopathy, and Leigh-like syndrome, 3-MGA 3-methylglutaconic acid, 3-MGC 3-methylglutaric acid, MND motor neurone disease, Psych. psychiatric, SEM saccadic eye movement, SERACC1 Serine Active Site Containing protein 1, VSSP vertical supranuclear saccade palsy