Shwachman-Diamond Syndrome (SDS)

SDS patients have poor food absorption (malabsorption) and low white blood cell counts (neutropenia). Most patients are diagnosed in infancy. Males and females are affected equally.

1. What are the major findings on physical examination?
1. Short stature
2. Problems with bones ("metaphyseal dysostosis", a specific finding seen on x-rays).
   
   
2. What is the age at diagnosis?
1. The diagnosis of SDS is usually made in the first year of life.
   
   
3. What is the pattern of bone marrow failure?
1. Neutropenia (low white blood count; white cells help the body fight off infection)
2. Anemia (low red blood cell count) may develop (often with large red cells).
3. Low platelet count may develop (platelets are the cells in the blood which help the blood to clot).
4. Aplastic anemia is diagnosed when all 3 types of cells (red cells, white cells and platelets) are abnormally low because the bone marrow is not producing them.
   
   
4. What specific kinds of cancer develop?
1. Leukemia (cancer of the blood and bone marrow)
   
   
5. How is SDS specifically diagnosed?
1. Reduced digestive enzyme production by the pancreas ("Pancreatic insufficiency"), which can be measured by various laboratory or x-ray tests:
1. Low serum trypsinogen and isoamylase (key digestive enzymes made by the pancreas)
2. Abnormal amounts of fat in the stool
3. Low pancreatic enzymes after stimulation of the pancreas
4. Small or fatty pancreas on ultrasound or CT scan imaging of the pancreas
   
2. Bone marrow failure
1. Low neutrophils in blood on at least 3 occasions
2. May have low hemoglobin and/or platelets
3. Genetic testing
1. The disease appears to be inherited in an autosomal recessive manner. This means that illness occurs only if a person has two abnormal (mutant) copies of the SDS gene. Laboratories can now identify the specific genetic "error" (or mutation) in some patients, in a gene called SBDS, which stands for Shwachman Bodian Diamond Syndrome.