Lysosomal storage diseases (LSDs)

What are lysosomal storage diseases (LSDs)?

Lysosomal storage diseases are a group of about 50 disorders. Children with a lysosomal storage disease are missing certain enzymes or have enzymes that don’t work how they should. LSDs are congenital diseases that develop during fetal growth.

Enzymes are small substances in your body that help break down and recycle complex chemicals important for the function and maintenance of our bodies. When these chemicals can’t get broken down, they build up and can cause cell damage in the skeleton, skin, brain, heart, nervous system and liver.

What are the different types of lysosomal storage diseases (LSDs)?

We can help patients with any of the 50 different lysosomal storage diseases. While all these conditions are rare, we most commonly treat:

• Gaucher disease - This condition can cause your child to have an enlarged liver and spleen, along with blood and bone issues.

• Fabry disease - This disease can create a burning sensation in the feet and hands, and skin rashes in some children. It can also affect the kidneys.

• Mucopolysaccharidosis - This is a group of conditions that affects bone growth and can lead to short stature (height), stiff joints, an enlarged liver and heart and developmental delay.

• Pompe disease - This condition causes muscle damage and can lead to muscle weakness, an enlarged heart and respiratory problems.

• Tay-Sachs disease - This rare disease causes fatal damage to the brain and spinal cord. Children with this condition typically start showing severe developmental delays around 6 months of age and only live for a few years.

• Niemann-Pick disease - This disease leads to enlarged organs, lung problems and progressive brain damage.

What are the signs and symptoms of lysosomal storage diseases (LSDs)?

Lysosomal storage disease is a broad category with many different conditions, so symptoms vary depending on which disease a child has. Common symptoms include:

• Short stature (height)

• Developmental delays or regression (loss of learned skills)

• Recurrent ear and upper respiratory infections

• Hernias

• Distinctive facial features (thick eyebrows, overgrown gums, severely large tongue and/or thick lips)

• Enlarged liver and/or spleen

• Joint issues

How are lysosomal storage diseases (LSDs) diagnosed?

Often the first sign of a lysosomal storage disease is an enlarged liver and developmental delays. Many children also have poor growth and have many infections.

We can make an accurate diagnosis with a physical exam and blood and urine tests. Ideally, we can make a diagnosis before age 2, but most children receive a diagnosis between ages 4 and 5. The sooner we can make a diagnosis, the better. That way, we can get your child on a treatment plan and connect you to the medical care and resources your family will need.

What causes lysosomal storage diseases (LSDs)?

Lysosomal storage diseases are caused by genes that are passed down from parent to child. These genes cause a child to not have certain enzymes or to have enzymes that don’t work properly. This leads to an incorrect “storage” of harmful material in various cells in the body.

How are lysosomal storage diseases (LSDs) treated?

Your child’s treatment will depend on the type of lysosomal storage disease they have. Common therapies include:

Enzyme replacement therapy - The goal of enzyme replacement therapy is to infuse your child with healthy, functioning enzymes. These new enzymes will help their body break down the specific chemical building up in their body, based on type of the disease they have. This therapy is safe and effective with few side effects.

Children typically receive enzyme infusions every week or every other week. During this process, we place a catheter (a small tube) underneath a child’s skin, instead of a needle. Enzyme replacement therapy is a lifelong treatment. Enzyme replacement therapy is typically used for children with:

• Gaucher disease

• Fabry disease

• Mucopolysaccharidosis

• Pompe disease

Bone marrow transplant - For some lysosomal storage diseases, enzyme replacement therapy doesn’t manage the disease well, especially for disorders that affect the brain. Bone marrow transplants can help some of these children. Most commonly, bone marrow transplants are used to try to prevent progressive mental disabilities in newborns who’ve been diagnosed with Hurler disease.

Bone marrow transplants can be hard on a child’s body. That’s why we only use this therapy when enzyme replacement therapy doesn’t work.

Medication management - Depending on the type of lysosomal storage disease, we might use medication to help control their symptoms. For example, if your child’s condition causes epilepsy, we’ll use an anti-seizure medication. If your child’s condition causes heart problems, we might prescribe heart medication.