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5 Things You Should Know About Acid Sphingomyelinase Deficiency

Acid sphingomyelinase deficiency (ASMD), including Niemann-Pick disease (NPD), is a spectrum of rare genetic diseases that are progressive and don’t currently have a cure. The condition affects the way fats, lipids and cholesterol are stored in or removed from your body.

ASMD includes two subgroups, neuronopathic (type A) and non-neuronopathic (type B), while there are three common forms of Niemann-Pick disease, types A, B and C. Each type involves different organs and each type can cause different symptoms and may occur at different times throughout life.

Our contributor Sara McGlocklin’s daughter Marian has been living with NPD type C. She just celebrated her 5th birthday. Although the family is celebrating this milestone, they continue their fight for a cure through their organization, Hope for Marian charitable foundation.

“We feel the isolation at times and the pangs of sadness over facing this enormous challenge with Niemann-Pick type C (NPC) disease,” said McGlocklin. “NPC can feel like an anvil hanging over one’s head, attempting to take their memory, their speech, and their movement. It can cause hallucinations, take their ability to eat an ice cream, to hold a hand, run through a park, sit up, smile at a joke, say hi, bye, I love you.”

Here are five things you should know about acid sphingomyelinase deficiency:

1. ASMD is caused by the body’s difficulty processing different fats.

NPD types A and B occur when genetic differences cause cells in the body to not have the enzyme acid sphingomyelinase (ASM). This substance is required to break down (metabolize) a fatty substance called sphingomyelin, which is found in every cell in the body. The lack of sphingomyelinase causes buildup of harmful amounts of lipids in the organs including the liver, spleen, bone marrow, brain, nerves, and, in severe cases, lungs. Sphingomyelin builds up inside cells, killing them, and making it difficult for organs to function normally.

Type A occurs mainly in infants and most do not live beyond their first few years. Most people affected with type B survive into adulthood. Type C occurs when the body cannot properly break down cholesterol and other fats (lipids). The genetic mutations of this type cause cholesterol and other fats to accumulate in the liver, spleen, lungs, and the brain.

2. No two cases of acid sphingomyelinase deficiency are the same.

Because ASMD is rare, every individual case is unique, and affected individuals will not have the same symptoms. Some will develop severe signs and symptoms early on, while others may not develop symptoms until well into adult life.

The signs and symptoms of NPD will depend on the type and severity of the disease.  Some symptoms may include swelling of the abdomen from enlargement of the liver and spleen, difficulty performing motor skills such as walking, difficulty eating or swallowing, frequent respiratory infections, poor coordination and a loss of muscular functioning, to name a few.

3. A doctor will use a variety of tests to look for characteristics of ASMD.

A diagnosis of ASMD begins with a thorough physical exam, detailed medical history, and discussion about symptoms and family health history. Tests using blood or skin samples (biopsy) can measure sphingomyelinase in white blood cells to help confirm the diagnosis. DNA testing and magnetic resonance imaging (MRI) of the brain may also be done to make a diagnosis.

4. There’s currently no cure for ASMD, but a few therapies show promise.

No cure exists for ASMD, and no effective treatment is available to people with type A or B. For people with mild to moderate type C, a drug called miglustat (brand name Zavesca) may be an option. It’s not FDA approved for Niemann-Pick disease, but early evidence suggests it may be helpful and doctors can prescribe it off label.

According to the National Organization for Rare Disorders, clinical trials are currently underway to study enzyme replacement therapy (ERT) to treat adults with ASMD.

Physical therapy is also an important part of treatment to help maintain mobility as long as possible. People with Niemann-Pick disease need to see their doctors regularly because the disease progresses and symptoms worsen.

5. If you’re facing an ASMD diagnosis, you’re not alone.

When you or a loved one receives an ASMD or Niemann-Pick disease diagnosis, it can be hard to know what to do next. The National Niemann-Pick Disease Foundation offers more information about the condition, including research, resources for families and how to cope emotionally with a diagnosis.

Header image via Evgeniia Siiankovskaia/Getty Images