Acid sphingomyelinase
Niemann-Pick Disease A/B: Acid Sphingomyelinase Enzyme Analysis
Niemann-Pick Disease A/B: Acid Sphingomyelinase Enzyme Analysis
This test measures acid sphingomyelinase enzyme activity and can be used as a first-tier test for patients with a clinical suspicion of Niemann-Pick disease A/B. Confirming deficient enzyme activity is the gold standard in diagnosis and can be used to support the interpretation of SMPD1 variants and monitor patients undergoing treatment.
Niemann-Pick disease A/B
Clinical Information
Niemann-Pick disease caused by acid sphingomyelinase deficiecncy is subdivided into two types. Type A, also called neuronopathic, is the more severe. These patients will usually present with hepatosplenomegaly within the first few months and will have progressive neurologic deterioration typically beginning by 12 months. A cherry-red spot on the retina will eventually be present in all affected children. Children with Niemann-Pick type A do not typically survive past 3 years.
Type B, or non-neuronopathic, is usually milder with a later onset. Progressive hepatosplenomegaly, gradual deterioration in pulmonary function, and an abnormal lipid profile are common manifestations for these patients. A small percentage of individuals with type B will have neurologic signs or a cherry-red spot.
Technical Information
Liquid chromatography-tandem mass spectrometry (LC-MS/MS)
Specimen Requirements
DBS: Approximately 75 uL of blood should be applied to each of the five circles on filter paper dried blood spot card. Allow blood to dry for at least 4 hours before shipping.
Transport Instructions
DBS: Ship DBS card at ambient temperature.
Associated Tests
Connect With Our Experts
Call 1-800-473-9411 to speak with our team of laboratory genetic counselors for questions or additional information.
Robin Fletcher, MS, CGC
Falecia Thomas, MS, CGC
Alex Finley, MS, CGC