Reviewed January 2008
What is the official name of the SMPD1 gene?
The official name of this gene is “sphingomyelin phosphodiesterase 1, acid lysosomal.”
SMPD1 is the gene's official symbol. The SMPD1 gene is also known by other names, listed below.
What is the normal function of the SMPD1 gene?
The SMPD1 gene carries the instructions to make an enzyme called acid sphingomyelinase. This enzyme is found in lysosomes (small compartments in the cell that digest and recycle molecules) and is responsible for the conversion of a lipid (fat) called sphingomyelin into another type of lipid called ceramide. This lipid conversion is critical for the normal structure and function of cells and tissues.
One copy of this gene is inherited from each parent; however, only the gene inherited from a person's mother (the maternal copy) is active. This parent-specific gene activation is called genomic imprinting. If the maternal copy of the SMPD1 gene is lost because of a chromosomal change or a gene mutation, a person will have no active copies of the gene because the gene inherited from a person's father (the paternal copy) is inactive.
How are changes in the SMPD1 gene related to health conditions?
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Niemann-Pick disease - caused by mutations in the SMPD1 gene
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More than 100 mutations in the SMPD1 gene have been found to cause Niemann-Pick disease types A and B. Mutations that alter the SMPD1 gene generally cause a significant reduction or complete absence of acid sphingomyelinase activity in cells. This lack of enzyme activity leads to the accumulation of sphingomyelin, cholesterol, and other types of lipids within the cells and tissues of affected individuals. Mutations that cause the enzyme to be inactive tend to cause the more severe Niemann-Pick disease type A. Mutations that cause the production of a defective enzyme that retains some activity often cause the milder Niemann-Pick disease type B. A shortage of enzyme activity within cells allows lipids to accumulate, which disrupts normal cell function and leads to cell death.
Where is the SMPD1 gene located?
Cytogenetic Location: 11p15.4-p15.1
Molecular Location on chromosome 11: base pairs 6,368,230 to 6,372,801
The SMPD1 gene is located on the short (p) arm of chromosome 11 between positions 15.4 and 15.1.
More precisely, the SMPD1 gene is located from base pair 6,368,230 to base pair 6,372,801 on chromosome 11.
See How do geneticists indicate the location of a gene? in the Handbook.
Where can I find additional information about SMPD1?
What other names do people use for the SMPD1 gene or gene products?
- ASM
- ASM_HUMAN
- NPD
- sphingomyelin phosphodiesterase 1, acid lysosomal (acid sphingomyelinase)
Where can I find general information about genes?
The Handbook provides basic information about genetics in clear language.
These links provide additional genetics resources that may be useful.
What glossary definitions help with understanding SMPD1?
acids ;
cell ;
ceramides ;
cholesterol ;
enzyme ;
gene ;
imprinting ;
lipid ;
lysosome ;
maternal ;
molecule ;
mutation ;
sphingomyelins ;
tissue
You may find definitions for these and many other terms in the Genetics Home Reference
Glossary.
The resources on this site should not be used as a substitute for
professional medical care or advice. Users seeking information about
a personal genetic disease, syndrome, or condition should consult with a qualified
healthcare professional.
See How can I find a genetics professional in my area? in the Handbook.