Niemann-pick types a/b

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What is the life expectancy for Niemann-Pick disease (SMPD1-associated)?

Life expectancy for Niemann-Pick disease (SMPD1-associated) varies depending on which type it is. Children with type A typically pass away in early childhood (most by age 3). People with type B usually survive into adulthood.

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Is Niemann-Pick disease (SMPD1-associated) more common in certain populations?

If I have a child with Niemann-Pick disease (SMPD1-associated), does that mean I am a carrier?

If I have a child with Niemann-Pick disease (SMPD1-associated), what are the chances that I will have another child with Niemann-Pick disease (SMPD1-associated), as well?

When should a doctor suspect that a person has Niemann-Pick disease (SMPD1-associated)?

Are there certain specific changes/mutations in the SMPD1 gene that are more common?

How good is the genetic testing for Niemann-Pick disease (SMPD1-associated) at finding changes/mutations in SMPD1?

Do people with Niemann-Pick disease (SMPD1-associated) lose all function of the acid sphingomyelinase enzyme?

Does the amount of functioning acid sphingomyelinase a person has impact the severity of the symptoms of Niemann-Pick disease (SMPD1-associated)?

I've heard that some doctors use a bone marrow biopsy to test for Niemann-Pick disease (SMPD1-associated). Is this a better or worse test?

What degree of developmental or intellectual disability is expected in Niemann-Pick disease type A?

How common is it to be a carrier for Niemann-Pick disease (SMPD1-associated) type A if I have Ashkenazi Jewish ancestry?

Can women with Niemann-Pick disease type B get pregnant?

If I have Niemann-Pick disease type B, what are the risks to my children?

Is Niemann-Pick disease (SMPD1-associated) more common in certain populations?

Niemann-Pick disease (SMPD1-associated) is more common in the Ashkenazi Jewish population. Specifically, type A is more common in people from this population. About 1 in 40,000 people with Ashkenazi Jewish ancestry has type A. There are 3 specific changes/mutations in the SMPD1 gene that account for 90% of the mutations in the Ashkenazi Jewish population. It is estimated that between 1 in 80 to 1 in 100 people with Ashkenazi Jewish ancestry are carriers for Niemann-Pick disease type A.

If I have a child with Niemann-Pick disease (SMPD1-associated), does that mean I am a carrier?

Since Niemann-Pick disease (SMPD1-associated) is inherited in an autosomal recessive manner, your child had to have inherited a change/mutation in both copies of the SMPD1 gene. That is, both Mom's copy and Dad's copy of the gene must have had a change/mutation. Therefore, both parents of the child are carriers for Niemann-Pick disease (SMPD1-associated).

If I have a child with Niemann-Pick disease (SMPD1-associated), what are the chances that I will have another child with Niemann-Pick disease (SMPD1-associated), as well?

If the same parents of a child with Niemann-Pick disease (SMPD1-associated) are having another child, there is a 25% (1 in 4) chance that the child will have Niemann-Pick disease (SMPD1-associated). There is a 50% (1 in 2) chance that the child will be a carrier for Niemann-Pick disease (SMPD1-associated). There is a 25% (1 in 4) chance that the child will not have Niemann-Pick disease (SMPD1-associated) or be a carrier. These chances are the chances for each and every pregnancy a couple has. In other words, this does not mean that 1 in 4 of their children will have Niemann-Pick disease (SMPD1-associated), but that each child who is born to the couple has a 1 in 4 chance of having Niemann-Pick disease (SMPD1-associated).

When should a doctor suspect that a person has Niemann-Pick disease (SMPD1-associated)?

Niemann-Pick disease type A should be suspected in a newborn child that has a large liver and spleen (hepatosplenomegaly), developmental delay, lung disease, and cherry-red spot found on an eye exam. Type B should be suspected in a child or older person with a large liver and spleen (hepatosplenomegaly), lung disease, high levels of fats in the blood, and low platelet count.

Are there certain specific changes/mutations in the SMPD1 gene that are more common?

There are some specific changes/mutations in SMPD1 that are more common to find in people with Niemann-Pick disease (SMPD1-associated), which includes type A and type B. There are 3 specific changes that account for about 90% of the changes/mutations in the Ashkenazi Jewish population that cause type A. These changes are called: p.Arg498Leu, p.Leu304Pro, and p.Phe333SerfsTer52. There is 1 specific change that accounts for almost 90% of the changes/mutations in North African individuals, 100% of individuals from Grand Canaria Island, and 20-30% of people from the USA that cause type B. This change is called p.Arg610del.

How good is the genetic testing for Niemann-Pick disease (SMPD1-associated) at finding changes/mutations in SMPD1?

Each specific genetic test performs differently when looking for changes in SMPD1. However, sequence analysis, which reads the SMPD1 gene code from start to finish to look for spelling mistakes, finds 95% of the genetic changes/mutations. In other words, 95% of people who have low levels of acid sphingomyelinase, the enzyme involved in Niemann-Pick disease (SMPD1-associated), will have a SMPD1 change/mutation found by sequence analysis.

Do people with Niemann-Pick disease (SMPD1-associated) lose all function of the acid sphingomyelinase enzyme?

Not necessarily. People with Niemann-Pick disease (SMPD1-associated) usually have less than 10% of the normal function. Therefore, many people still have some functioning acid sphingomyelinase, but a lot less than healthy people.

Does the amount of functioning acid sphingomyelinase a person has impact the severity of the symptoms of Niemann-Pick disease (SMPD1-associated)?

Looking at the level of acid sphingomyelinase enzyme activity is not a good way to guess how severe a person's symptoms will be. The level of activity can help diagnose the disease in the first place, but should not be used to predict severity.

I've heard that some doctors use a bone marrow biopsy to test for Niemann-Pick disease (SMPD1-associated). Is this a better or worse test?

Bone marrow biopsy is not necessary to diagnose Niemann-Pick disease (SMPD1-associated). Some doctors may have ordered this testing because the disease can impact the function of the bone marrow. However, you can get the same answers by testing blood. Bone marrow biopsy should only be done in very special circumstances if the doctor thinks the patient's bone marrow is greatly affected.

What degree of developmental or intellectual disability is expected in Niemann-Pick disease type A?

Children with Niemann-Pick disease type A do not typically exceed a developmental age of 12 months old with regards to language skills and about 9-10 months old for motor skills.

How common is it to be a carrier for Niemann-Pick disease (SMPD1-associated) type A if I have Ashkenazi Jewish ancestry?

It is estimated that between 1 in 80 to 1 in 100 people with Ashkenazi Jewish ancestry are carriers for Niemann-Pick disease (SMPD1-associated) type A.

Can women with Niemann-Pick disease type B get pregnant?

There are previous reports of women with mild forms of Niemann-Pick disease type B getting pregnant and having children. For the most part, women with this condition can have normal pregnancies and healthy babies.

If I have Niemann-Pick disease type B, what are the risks to my children?

Every child of a person with Niemann-Pick disease type B will be a carrier for an SMPD1 change/mutation. If the other parent is a carrier of an SMPD1 change/mutation, there is a 50% chance that each child will also have Niemann-Pick disease. If the other parent also has Niemann-Pick disease (SMPD1-associated), all children will have Niemann-Pick disease.

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