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Paediatric Laboratory Medicine

Niemann Pick Disease Type A and B: SMPD1 Recurrent Mutations

Clinical Significance

Niemann disease types A and B (NP) are lysosomal storage disorders resulting from the accumulation of sphingomyelin, cholesterol and other lipids in the cells of affected individuals due to a deficiency of sphingomyelinase activity. Niemann Pick type A (NPA) presents in infancy with organomegaly and rapid neurodegeneration leading to death by ~3 years of age. Niemann Pick type B (NPB) is clinically heterogeneous and individuals can present with multiple findings including hepatosplenomegaly, growth retardation, frequent respiratory infections, fatigue and hematologic abnormalities. Individuals with NPB usually survive into adulthood. DNA testing for three mutations common in the Ashkenazi Jewish population for NPA and one mutation in NPB is performed. NP is an AR disorder caused by mutations in the SMPD1 gene, located on chromosome 11 (11p15.4). Four mutations in the SMPD1 gene account for greater than 95% of the mutations seen in AJ individuals affected with Niemann Pick disease, type A & B.

Test Name

Niemann Pick Disease Type A and B: SMPD1 Recurrent Mutations

Alternate Name/ Synonym

  • Sphingomyelinase Deficiency

Gene Name

  • SMPD1

Alternate Gene Name


Test Code



Molecular Genetics


Targeted analysis of recurrent muations

External Proficiency Testing


Turn Around Time

2 weeks (Prenatal samples), 2-3 weeks (Pregnancy/Urgent samples), 4-6 weeks (Routine)


Sphingomyelin phosphodiesterase 1, acid lysosomal


Niemann Pick Disease Type A and B (part of the Ashkenazi Jewish screening panel)

Specimen Type

Blood; gDNA. 

For details about specimen requirements, please refer to: Specimen Type & Requirements (PDF).

Minimum Specimen Requirements

5-10 mL EDTA or ACD 0.5 mL EDTA (neonate); minimum 10 ug in 100 uL low TE (pH8.0)


Room Temperature

Special Requirements

Special Instructions for Genome Diagnostics Samples

If sample shipment >48 hours, ship on ice.

Approval is not required

CPT Codes


Shipping and Contact Information

The Hospital for Sick Children
Rapid Response Laboratory
170 Elizabeth Street, Room 3642
Toronto, ON
M5G 2G3
Phone: 416-813-7200
Phone: 1-855-381-3212


Interpretation is provided in report