About Shwachman-Diamond Syndrome (SDS)
Shwachman-Diamond Syndrome was first identified in 1964. It involves many systems in the body, including the pancreas, bone marrow, and skeleton.
Cause
Shwachman-Diamond Syndrome, commonly referred to as SDS, is caused by an autosomal genetic mutation. This means that a gene mutation is provided from each parent. The genetic mutation that causes SDS is located on the long arm of chromosome 7. However, about 10% of patients have symptoms of Shwachman-Diamond Syndrome (SDS) but do not have a known genetic mutation.
Early Signs
Infants with Shwachman-Diamond Syndrome usually show symptoms early. They may have feeding problems, failure to thrive (do not gain weight), do not grow, and may have frequent infections. They may also have skeletal abnormalities.
What Body Systems are Involved?
Many body parts are affected by Shwachman-Diamond Syndrome among them are the bone marrow, pancreas, skeleton, kidneys, liver, brain, teeth, and immune system.
Pancreatic Issues
The pancreas is an organ that has two functions. It produces insulin to control blood sugars in the body. It also produces enzymes to digest food and nutrients. In patients with Shwachman-Diamond Syndrome, the part of the pancreas that produces enzymes does not work properly. This results in greasy, frequent, and foul-smelling stools. Enzyme replacement will help the patient digest food and provide needed nutrition. Because fats are not easily digested attention should be given to monitoring the levels of the fat-soluble vitamins ( A, D, E, and K) and replacement supplements provided when necessary.
In about 50% of patients, pancreatic function improves with age and enzyme replacement therapy may be discontinued. Enzymes should only be discontinued after consultation and confirmative testing by a gastroenterologist. Slow improvement in weight is usually seen but growth velocity may not improve.
Some patients also have issues with blood sugar levels.
Skeletal
Bone abnormalities are reported in some patients. These usually involve the hips, rib cage, femur, and tibia. If severe enough they may require surgical intervention.
Liver
An enlarged liver and elevated liver enzymes are frequently seen in young patients. Liver enzyme levels do normalize with age. Chronic liver disease has been documented.
Neuro / Psych Issues
Developmental delays and learning difficulties are seen in some Shwachman-Diamond Syndrome patients. These may include learning disabilities, developmental delays, ADHD, and behavior issues. Testing is recommended if there is an indication of these issues.
Bone Marrow
The bone marrow produces all lines of blood cells: white cells, red cells, and platelets. In Shwachman-Diamond Syndrome (SDS) patients the bone marrow does not function properly. As a result, the patient may have decreased numbers of white cells, red cells, and/or platelets.
Anemia
Anemia refers to a decreased number of red blood cells in the bloodstream. Red blood cells are needed to carry oxygen to the cells in the body.
Neutropenia
Neutropenia is a condition caused by a reduction in the number of white blood cells called neutrophils. These cells are responsible for helping the body fight bacteria and fungal infections. Patients with an absolute neutrophil count (ANC) that is low (below 1500 per microliter) may be at risk for life-threatening infections.
Thrombocytopenia
Blood platelets clot the blood and prevent bruising. A normal platelet count is above 150,000 per microliter. A decreased number of these cells is called thrombocytopenia. If the platelet count is too low, platelet transfusions may be necessary to prevent hemorrhaging.
It is strongly recommended that every Shwachman-Diamond Syndrome (SDS) patient be seen regularly by a hematologist, a physician who specializes in blood issues. The patient’s blood counts should be regularly monitored. It is further recommended that all patients have periodic bone marrow biopsies to monitor how the bone marrow is functioning.
Further complications that can develop are leukemia, myelodysplastic syndrome (MDS), and aplastic anemia. These complications are life-threatening and require immediate care by specialists who are experienced in treating SDS patients.
Other Possible Complications
Less common features include dental dysplasia and increased dental caries, lung disease, testicular fibrosis, and cardiac lesions.
Shwachman-Diamond Syndrome (SDS) is a very rare condition. For this reason, not many physicians are knowledgeable about it. We feel that the best possible care for your child can be obtained by taking him/her to physicians who have knowledge and experience in caring for Shwachman-Diamond Syndrome patients. We are happy to help you find a specialist.
Symptoms & Features Of
Shwachman-Diamond Syndrome
Digestive
Diarrhea is almost always present in infancy. Stools contain an excessive amount of fat and are foul-smelling and greasy in appearance. Improvement in stools is seen after enzyme replacement therapy is begun. Although weight gain is noted, growth does not seem to improve. Some older patients are able to discontinue enzyme replacement with no clinical consequences.
Bone Marrow
As a result of dysfunction of the bone marrow, patients may have a decrease in any or all types of blood cells. There may be decreased numbers of neutrophils (the white blood cell that helps fight infection), platelets (the blood cell that helps clot the blood), or red blood cells. Blood cell counts should be monitored regularly. Shwachman-Diamond Syndrome patients have a propensity to myelodysplasia or leukemic transformation, for this reason bone marrow aspirates and biopsies are recommended.
Neutropenia
Neutropenia is present when the counts are lower than 1500 per microliter. Neutrophils are a type of white blood cell important in fighting bacterial infections. Neutropenia is seen, at some time during the course of the disease, in virtually all patients. Many patients are prone to repeated bacterial infection. Some of these infections may be life threatening. Close attention should be paid to infection, with appropriate treatment instituted as quickly as possible.
Thrombocytopenia
The blood also contains cells called platelets. It is their function to clot the blood when bleeding occurs. Normally, platelet counts are above 150,000 per microliter. In about 35% of patients with Shwachman-Diamond Syndrome this count is below that number; this is called thrombocytopenia. Easy bruisability is one indication of thrombocytopenia, but severe bleeding is unusual. Precautions may be required before dental work or surgery, and platelet transfusions or medications may be necessary to diminish the risk of abnormal bleeding.
Anemia
Anemia occurs when the hemoglobin level is under 10gm/dl, and has been observed in up to 40% of patients with Shwachman-Diamond Syndrome. Anemia is usually mild and does not respond well to treatment with iron, folic acid and vitamin B-12.
Skeleton
Bone lesions have been reported in 10 to 15% of patients. The bone abnormalities are called metaphyseal chondrodysplasia. X-ray changes are most commonly seen in the hip, femur, tibia (leg bone) and ribs. These changes can be severe enough to require surgical correction.
Liver
Abnormalities in the structure of the liver and in function are not uncommon. Hepatomegaly (enlarged liver) occurs in about 2/3 of patients under the age of five years of age, but is less frequent in older children. Serum liver enzymes are elevated in 50 to 75% of cases, again most often in young children and tending to fall with age. Chronic liver disease has been reported.