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Shwachman-Diamond syndrome

Shwachman-Diamond syndrome (SDS) is a rare congenital disorder characterized by exocrine pancreatic insufficiency, bone marrow dysfunction, skeletal abnormalities, and short stature. After cystic fibrosis (CF), it is the second most common cause of exocrine pancreatic insufficiency in children. more...

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Clinical Features

This syndrome shows a wide range of abnormalities and symptoms. The main characteristics of the syndrome are exocrine pancreatic dysfunction, haematologic abnormalities and growth retardation. Neutropenia may be intermittent or persistent and is the most common haematological finding. Low neutrophil counts leave patients at risk of developing severe recurrent infections that may be life-threatening. Anemia (low red blood cell counts) and thrombocytopenia (low platelet counts) may also occur. Bone marrow is typically hypocellular, with maturation arrest in the myeloid lineages that give rise to neutrophils, macrophages, platelets and red blood cells. Patients may also develop progressive marrow failure or transform to acute myelogenous leukemia. Pancreatic exocrine insufficiency arises due to a lack of acinar cells that produce digestive enzymes. These are extensively depleted and replaced by fat. A lack of pancreatic digestive enzymes leaves patients unable to digest and absorb fat. However, pancreatic status may improve with age in some patients. More than 50% of patients are below the third percentile for height, and short stature appears to be unrelated to nutritional status. Other skeletal abnormalities include metaphyseal dysostosis (45% of patients), thoracic dystrophy (rib cage abnormalities in 46% of patients), and costochondral thickening (shortened ribs with flared ends in 32% of patients). Skeletal problems are one of the most variable components of SDS, with 50% affected siblings from the same family discordant for clinical presentation or type of abnormality. Despite this, a careful review of radiographs from 15 patients indicated that all of them had at least one skeletal anomaly, though many were sub-clinical.


Initially, the clinical presentation of SDS may appear similar to cystic fibrosis. However, CF can be excluded with a normal sweat chloride test result. The variation, intermittent nature, and potential for long-term improvement of some clinical features make this syndrome difficult to diagnose. SDS may present with either malabsorption, or hematological problems. Rarely, SDS may present with skeletal defects, including severe rib cage abnormalities that lead to difficulty in breathing. Diagnosis is generally based on evidence of exocrine pancreatic dysfunction and neutropenia. Skeletal abnormalities and short stature are characteristics that can be used to support the diagnosis. The gene responsible for the disease has been identified and genetic testing is now available. Though useful in diagnostics, a genetic test does not surmount the need for careful clinical assessment and monitoring of all patients.


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Aplastic anemia
From Gale Encyclopedia of Medicine, 4/6/01 by Rosalyn S. Carson-DeWitt


Aplastic anemia is a disorder in which the bone marrow greatly decreases or stops production of blood cells.


The bone marrow (soft tissue which is located within the hard outer shell of the bones) is responsible for the production of all the types of blood cells. The mature forms of these cells include red blood cells, which carry oxygen throughout the body; white blood cells, which fight infection; and platelets, which are involved in clotting. In aplastic anemia, the basic structure of the marrow becomes abnormal, and those cells responsible for generating blood cells (hematopoietic cells) are greatly decreased in number or absent. These hematopoietic cells are replaced by large quantities of fat.

Yearly, aplastic anemia strikes about 5-10 people in every one million. Although aplastic anemia strikes both males and females of all ages, there are two age groups that have an increased risk. Both young adults (between 15-30 years of age) and the elderly (over the age of 60) have higher rates of aplastic anemia than the general population. While the disorder occurs worldwide, young adults in Asia have a higher disease rate than do populations in North America and Europe.

Causes & symptoms

Aplastic anemia falls into three basic categories, based on the origin of its cause: idiopathic, acquired, and hereditary.

In about 60% of cases, aplastic anemia is considered to be idiopathic, meaning that the cause of the disorder is unknown.

Acquired aplastic anemia refers to those cases where certain environmental factors and physical conditions seem to be associated with development of the disease. Acquired aplastic anemia can be associated with:

  • Exposure to drugs, especially anti-cancer agents, antibiotics, anti-inflammatory agents, seizure medications, and antithyroid drugs (drugs given to stop the functioning of an overactive thyroid).
  • Exposure to radiation.
  • Chemical exposure (especially to the organic solvent benzene and certain insecticides).
  • Infection with certain viruses (especially those causing viral hepatitis, as well as Epstein-Barr virus, parvovirus, and HIV, the virus which can cause AIDS).
  • Pregnancy.
  • Certain other disorders, including a disease called paroxysmal nocturnal hemoglobinuria, an autoimmune reaction called graft-vs-host disease (which occurs when the body's immune system attacks and destroys the body's own cells), and certain connective tissue diseases.

Hereditary aplastic anemia is relatively rare, but does occur in Fanconi's anemia, Shwachman-Diamond syndrome, and dyskeratosis congenita.

Symptoms of aplastic anemia tend to be those of other anemias, including fatigue, weakness, tiny reddish-purple marks (petechiae) on the skin (evidence of pinpoint hemorrhages into the skin), evidence of abnormal bruising, and bleeding from the gums, nose, intestine, or vagina. The patient is likely to appear pale. If the anemia progresses, decreased oxygen circulating in the blood may lead to an increase in heart rate and the sudden appearance of a new heart murmur.


The blood count in aplastic anemia will reveal low numbers of all formed blood cells. Red blood cells will appear normal in size and coloration, but greatly decreased in number. Cells called reticulocytes (very young red blood cells, which are usually produced in great numbers by the bone marrow in order to compensate for a severe anemia) will be very low in number. Platelets and white blood cells will also be decreased in number, though normal in structure.

A sample of the patient's bone marrow will need to be removed by needle (usually from the hip bone) and examined under a microscope. If aplastic anemia is present, this examination will reveal very few or no hematopoietic cells, and replacement with fat.


The first step in the treatment of aplastic anemia involves discontinuing exposure to any substance that may be causing the disorder. Although it would seem that blood transfusions would be helpful in this disease, in fact, they only serve as a temporary help, and may complicate future attempts at bone marrow transplantation.

The most successful treatment for aplastic anemia is bone marrow transplantation. To do this, a marrow donor (often a sibling) must be identified. There are a number of tissue markers which must be examined to determine whether a bone marrow donation is likely to be compatible with the patient's immune system. Compatibility is necessary to avoid complications, including the destruction of the donor marrow by the patient's own immune system.

Patients who cannot undergo bone marrow transplant can be treated with a number of agents, including antithymocyte globulin (ATG), cyclophosphamide, steroids, and cyclosporine. These agents all have the potential to cause a number of troublesome side-effects. Furthermore, not all patients respond fully to these agents. Still, even among those patients who do have a good response, many later suffer a relapse (return) of aplastic anemia.


Aplastic anemia is a life-threatening illness. Without treatment, it will almost surely progress to death. Survival depends on how severe the disease is at diagnosis, which type of treatment a patient is eligible for, and what kind of response their body has to that treatment. The worst-prognosis type of aplastic anemia is one associated with very low numbers of a particular type of white blood cell. These patients have a high chance of dying from overwhelming bacterial infections. In fact, 80% of all patients treated with blood transfusions alone die within 18 months to two years. Patients who undergo bone marrow transplantation have a 60-90% chance of being cured of the disease.

Key Terms

Bone marrow
A substance found in the cavities of bones, especially the long bones and the sternum (breast bone). The bone marrow contains those cells which are responsible for the production of the blood cells (red blood cells, white blood cells, and platelets).

Bone marrow transplant
A procedure in which a quantity of bone marrow is extracted through a needle from a donor, and then passed into a patient to replace the patient's diseased or absent bone marrow.
Hematopoietic cells
Those cells which are lodged within the bone marrow, and which are responsible for producing the cells which circulate in the blood (red blood cells, white blood cells, and platelets).

Further Reading

For Your Information


  • Castro-Malaspina, Hugo and Richard J. O'Reilly. "Aplastic Anemia and Myelodysplastic Syndromes." In Harrison's Principles of Internal Medicine, edited by Anthony S. Fauci, et al. New York: McGraw-Hill, 1998.


  • Doney, Kristine, et al. "Primary Treatment of Acquired Aplastic Anemia: Outcomes with Bone Marrow Transplantation and Immunosuppressive Therapy." Annals of Internal Medicine 126(January 15, 1997): 107+.
  • Young, Neal. "Aplastic Anaemia." The Lancet 346(July 22, 1995): 228+.
  • Young, Neal, and Jaroslaw Maciejewski. "The Pathophysiology of Acquired Aplastic Anemia." The New England Journal of Medicine 336(May 8, 1997): 1365+.


  • Aplastic Anemia Foundation of America, Inc. P.O. Box 613, Annapolis, MD 21404. (800) 747-2820.

Gale Encyclopedia of Medicine. Gale Research, 1999.

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