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
ASM; NPD
Test Code
NPAB
Division
Molecular Genetics
Method
Targeted analysis of recurrent muations
External Proficiency Testing
CAP
Turn Around Time
2 weeks (Prenatal samples), 2-3 weeks (Pregnancy/Urgent samples), 4-6 weeks (Routine)
Protein
Sphingomyelin phosphodiesterase 1, acid lysosomal
Disease/Condition
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)
Storage/Transportation
Room Temperature
Special Requirements
Special Instructions for Genome Diagnostics Samples
If sample shipment >48 hours, ship on ice.
Approval is not required
CPT Codes
81479
Shipping and Contact Information
The Hospital for Sick Children
Rapid Response Laboratory
170 Elizabeth Street, Room 3642
Toronto,
ON
M5G 2G3
Canada
Phone: 416-813-7200
Phone: 1-855-381-3212
Interpretation
Interpretation is provided in report
Information Sheet: Ashkenazi Jewish Screening Panel