Shwachman-Diamond syndrome

What is Shwachman-Diamond syndrome? 

Shwachman-Diamond syndrome (SDS) is an inherited disease that affects several systems in a child’s body, including his bone marrow, pancreas and skeleton. Occasionally, other organs, such as the liver and teeth, are also involved.

Is SDS common?

No; in fact, it is quite rare, with an estimated incidence of 1 in every 77,000 births.

Who does SDS affect?

Shwachman-Diamond syndrome occurs more frequently in boys than girls (about 1.7 boys for every girl), and has been reported in all ethnic groups. 

What complications does SDS cause?

SDS affects different children in different ways. Complications often include the following:

• Pancreatic insufficiency results in a failure to produce enough of the enzymes required to properly digest food. That is why many children with SDS have persistent greasy and foul-smelling diarrhea and poor growth during their first years of life.
   
• The most common blood abnormality associated with SDS is a low number of the white blood cell type called neutrophils, which are crucial for fighting bacterial infections. As a result, patients are at increased risk of infection.
   
• Children with SDS may also be anemic due to a decreased production of red cells and low platelets (cells that are needed to form normal blood clots). They are slightly more likely to develop blood cancers such as myelodysplasia or leukemia.

If my child has SDS, what is the likelihood my other children will also have it? Do they need to be tested right away, even if they are not showing any symptoms?

If you or your child’s other parent are carriers of the gene for SDS (this is referred to as being a heterozygote), your other children have a 1 in 4 chance of having the disorder.

Since new gene mutations can sometimes arise, it is important to test both parents in order to evaluate the risk of having another affected child. In most cases, all other immediate members of a family are tested, even if they do not show any symptoms of SDS.

Causes

What causes Shwachman-Diamond syndrome?

90 percent of the time, SDS is caused by a mutation in a gene known as SBDS. Shwachman-Diamond syndrome is a recessively inherited disorder, meaning that a child must inherit two defective copies of the gene (one from each parent) to develop the disease.

The remaining 10 percent of children with Shwachman-Diamond syndrome have a normal SBDS gene, but develop the disease anyway. We believe that an as-yet-unidentified gene is involved in these cases.

Signs and symptoms 

What are the symptoms of SDS?

Symptoms can vary greatly from child to child. The most common symptoms are chronic, often greasy diarrhea, frequent infections due to low white blood cells and poor growth.

Other signs can include:

• anemia
• thrombocytopenia (occurring in up to 30 percent of children with SDS)
• skeletal abnormalities, including growth plate changes, short ribs, curvature of the spine (scoliosis), delayed tooth development, dental abscesses, cavities and gum problems