General Condition Information
What is Niemann-Pick disease
Niemann-Pick disease is a term used to describe a family of inherited (genetic) conditions that prevent the body from processing fatty substances normally. Acid sphingomyelinase deficiency (ASMD), also known as Niemann-Pick disease types A and B, occurs when the body cannot break down a compound called sphingomyelin properly. Niemann-Pick disease is named for the first two doctors to describe the condition.
An enzyme called acid sphingomyelinase (ASM) breaks down sphingomyelin. Sphingomyelin maintains the shape of cells, especially nerve cells, and also supports other important processes. Sphingomyelin gets broken down in lysosomes, which are the cell components that process nutrients.
Newborn screening can only identify ASMD (Niemann-Pick types A and B). Another related condition that newborn screening does not detect, Niemann-Pick type C, is described at MedlinePlus Genetics.
ASMD develops when the ASM enzyme is present at low levels or does not work correctly. This makes it harder for lysosomes to break down sphingomyelin.
The severity and type of ASMD depends on how well sphingomyelin breaks down. There are three main types of ASMD: infantile neurovisceral, chronic visceral, and chronic neurovisceral.
- Infantile neurovisceral AMD (Niemann-Pick disease type A), is more severe and has an earlier onset than other types of ASMD.
- Chronic visceral disease (Niemann-Pick disease type B) causes health problems in the bone marrow, liver, spleen, and lungs.
- Chronic neurovisceral disease has the same symptoms as chronic visceral disease, but also shows signs and symptoms in the nervous system.
Without treatment, high levels of sphingomyelin can damage the brain, lungs, spleen, and liver. This damage leads to the signs and symptoms of the condition, which may be life-threatening.
Newborn Screening and Follow-Up
Newborn screening for ASMD requires collecting a small amount of blood from your baby’s heel. To learn more about this process, visit the Blood Spot Screening page.
Screening measures how much ASM enzyme is in your baby’s blood. This enzyme is responsible for breaking down sphingomyelin. Babies with a low level of this enzyme might have ASMD.
If your baby’s blood spot screening result for ASMD is out-of-range, your baby’s health care provider will contact you. Together, you will discuss next steps and follow-up plans.
An out-of-range screening result does not mean that your baby definitely has the condition. It does mean that your baby needs more follow-up testing. To learn more about screening results, visit the Blood Spot Screening Results page.
Your baby may need the following tests after an out-of-range screening result:
- Blood tests
- Genetic testing using a blood sample
You should complete any recommended follow-up testing as soon as possible. Babies and infants with this condition can have serious health problems if they are not diagnosed and treated quickly.
False-positive newborn screening results for this condition can happen.
Newborn screening helps babies lead healthier lives. If your baby has an out-of-range result, follow up with your health care provider quickly. It is important to follow their instructions. Your baby may need to get treatment right away, even if they are not showing signs or symptoms. In some cases, your baby’s health care provider may decide it is best to watch (monitor) your baby to decide next steps. Careful monitoring and early treatment will help your baby stay as healthy as possible.
Signs of ASMD may appear anywhere from early infancy (infantile neurovisceral ASMD, type A) to mid-childhood or even adulthood (chronic visceral ASMD, type B). Some patients have symptoms in the nervous system and other organs that starts after infancy (chronic neurovisceral ASMD).
Early signs of the condition may include the following:
- Brain issues
- Large liver and spleen (hepatosplenomegaly)
- Failure to gain weight and grow (failure to thrive)
- Feeding problems
- Loss of developmental skills (developmental regression)
- Lung disease and lung infections
- Unusual eye findings (cherry-red spot)
- Vison and hearing loss
A change in the SMPD1 gene causes ASMD. This gene gives the body instructions for making the ASM enzyme that breaks down sphingomyelin.
A changed SMPD1 gene prevents the body from breaking down sphingomyelin properly. Sphingomyelin then builds up in special processing compartments of the cells called lysosomes. When lysosomes get too full, cells do not function properly. ASMD most seriously affects the cells of the brain, lungs, spleen, and liver.
- ASMD is an autosomal recessive condition. Babies inherit type A or B when each parent passes down a nonworking SMPD1 gene to their baby. Only babies with two nonworking SMPD1 genes—one from the mom and one from the dad—have this condition.
- People with one working copy and one nonworking copy of the SMPD1 gene are called carriers.
- Carriers do not have or develop the condition. However, they may pass down a nonworking copy of the gene to their children.
- If two parents are carriers of a nonworking copy of the SMPD1 gene, they have a 1 in 4 chance of having a child with ASMD.
- Carriers for ASMD often do not know they are carriers before having a child with the condition. In most cases, families have no history of the condition until the birth of a child with ASMD.
- Parents who already have a child with ASMD still have a 1 in 4 chance of having another child with ASMD. This 1 in 4 chance stays the same for all future children.
- Genetic counselors and medical geneticists can help families learn about this condition and the chance of having children with it. Visit the National Society of Genetic Counselors to find a genetic counselor and the American College of Medical Genetics and Genomics to find a medical geneticist.
Treatment and Management
It is important to talk to your health care provider about which treatment(s) are best for your baby. Treatment manages the health problems caused by this condition by reducing symptoms.
Treatments may include the following:
- Bone marrow transplant or enzyme replacement therapy (for type B)
- Medications to help cholesterol levels (statins)
- Physical and occupational therapy
Children who receive early and ongoing treatment for ASMD may live longer and have better growth. There is not yet effective treatment for brain issues by ASMD in the infantile neurovisceral and chronic neurovisceral forms of the disease. It is important to talk to your health care provider about how to best care for your baby. Health care providers will develop a plan that is tailored to the needs of each child.