Blood Diseases & Down Syndrome

The most common blood cell abnormalities diagnosed in patients with Down syndrome include: polycythemia (also known as erythrocytosis), macrocytosis, thrombocytopenia, thrombocytosis, leucopenia, leukemoid reactions, and transient myeloproliferative disorder.

POLYCYTHEMIA

Polycythemia or erythrocytosis means an elevated number of red blood cells. This is frequently seen in newborn babies with Down syndrome. In some babies, the elevation in the number of red blood cells can be associated with some types of congenital heart defects but the great majority of babies with Down syndrome who develop polycythemia don’t have an associated heart defect. Typically the polycythemia will resolve within the first few months of life especially if it is not associated with an underlying medical condition. In general polycythemia, regardless of the cause, won’t cause significant problems associated with the increased number of red cells. Occasionally some individuals may need to be treated if the number of red cells is extremely elevated and the blood gets too thick.

MACROCYTOSIS

Macrocytosis means enlargement of the red blood cells. This is a very common finding in newborn babies with Down syndrome. This hematologic finding persists throughout life in about two-thirds of individuals with Down syndrome. Medical conditions that can be associated with macrocytosis include hypothyroidism (insufficient production of thyroid hormone), megaloblastic anemia (decreased number of red cells because of deficiency in vitamin B12 and Folic acid), increased number of reticulocytes (young red blood cells) and some diseases of the liver and the bone marrow (the tissue found in the hollow interior of bones where all the blood cells are made). It is important to consider these medical conditions when an individual with Down syndrome is found with macrocytosis but in the great majority of cases, an apparent cause won’t be found. Macrocytosis shouldn’t cause any adverse medical effects.

THROMBOCYTOPENIA

Thrombocytopenia means a decreased number of platelets. This is a common diagnosis made in babies with Down syndrome. It can be seen associated with some types of congenital heart defects. Also, it is a frequent hematologic finding among newborns with Down syndrome without any heart problems; in these cases typically the low platelet count usually resolves within a few weeks. Having a platelet count that is too low may predispose an individual to bleed. Under some circumstances, patients who have significant thrombocytopenia may require platelet transfusions.

THROMBOCYTOSIS

Thrombocytosis means an elevated number of platelets. This is a rare hematologic finding in newborn babies with Down syndrome. When it occurs, it usually doesn’t cause any medical problem and it goes away spontaneously within the first weeks of life.

LEUKOPENIA

Leukopenia means a low number of white cells. The number of white cells tends to be slightly lower than the normal range in about one-third of individuals with Down syndrome. There is some concern that this may increase the risk for infections among patients with Down syndrome but this has not been clearly proven through medical research yet.

LEUKEMOID REACTION

Leukemoid reaction means a very elevated number of white cells. Babies born with Down syndrome can present with this blood cell abnormality within the first few months of life. This elevated white cell count typically goes away spontaneously. In some instances, it may be associated with a more serious medical condition (see transient myeloproliferative disorder).

TRANSIENT MYELOPROLIFERATIVE DISORDER (TMD)

This is a medical condition found almost exclusively in newborn babies with Down syndrome. Not every baby with Down syndrome will develop TMD; it is estimated that 10-20% of babies born with Down syndrome are diagnosed with TMD. This condition results from the rapid growth of abnormal white cells. The abnormal cells may go away without treatment, or they may need treatment. The choice of treatment or no treatment depends on whether certain harmful characteristics of the disease are observed in the baby. There are different ways to treat babies with TMD. The decision regarding what kind of therapy will be necessary depends on the type of harmful characteristics that are seen in the baby. Some of the treatments that have been used include leukophoresis (a procedure that filters abnormal cells from a baby’s blood) and chemotherapy (anti-cancer drugs). In the great majority of patients, the prognosis of TMD is good with complete resolution of the disease without any treatment; however, a few patients with TMD don’t show improvement and develop cancer in the blood or leukemia. In some patients, leukemia develops years after TMD is resolved. In general, babies who are diagnosed with TMD will need to be followed very closely to make sure that the disease goes away. Because TMD is potentially cancerous, children who are diagnosed with this disorder should be monitored closely for years after the signs and symptoms of the condition resolve. The evaluation and treatment of TMD should be discussed with a hematologist/oncologist.

Individuals with Down syndrome have an increased risk for the development of precancerous conditions such as myelodysplastic syndrome, potentially cancerous conditions such as transient myeloproliferative disorder, and cancerous conditions like leukemia.

MYELODYSPLASTIC SYNDROME (MDS)

Myelodysplastic syndrome (MDS) is a pre-cancerous condition that originates in the bone marrow in which there are cells that are abnormal. The bone marrow is the tissue found in the hollow interior of bones where all the blood cells are made.

The diagnosis of MDS is suspected when the blood cells start showing changes like a decrease in the platelet count (thrombocytopenia), an increase in the size of the RBC (macrocytosis), a decrease in the number of red cells and level of hemoglobin (anemia), or a decrease or increase in the number of white cells.

If not treated, MDS will progress to leukemia. The time frame for the development of leukemia ranges from months to years. The evaluation and treatment of MDS should be discussed with a hematologist/oncologist (a physician who specializes in disorders of the blood cells and the care of cancer patients).

TRANSIENT MYELOPROLIFERATIVE DISORDER (TMD)

This is a medical condition found almost exclusively in newborn babies with Down syndrome. Not every baby with Down syndrome will develop TMD; it is estimated that 10-20% of babies born with Down syndrome are diagnosed with TMD. This condition results from the rapid growth of abnormal white cells. The abnormal cells may go away without treatment, or they may need treatment. The choice of treatment or no treatment depends on whether certain harmful characteristics of the disease are observed in the baby. There are different ways to treat babies with TMD. The decision regarding what kind of therapy will be necessary depends on the type of harmful characteristics that are seen in the baby. Some of the treatments that have been used include leukophoresis (a procedure that filters abnormal cells from their blood) and chemotherapy (anti-cancer drugs). In the great majority of patients, the prognosis of TMD is good with complete resolution of the disease without any treatment; however, a few patients with TMD don’t show improvement and develop cancer in the blood or leukemia. In some patients, leukemia develops years after TMD is resolved. In general, babies who are diagnosed with TMD will need to be followed very closely to make sure that the disease goes away. Because TMD is potentially cancerous, children who are diagnosed with this disorder should be monitored closely for years after the signs and symptoms of the condition resolve. The evaluation and treatment of TMD should be discussed with a hematologist/oncologist.

LEUKEMIA

Leukemia is a cancer of the blood cells. Leukemia develops when young and abnormal cells, called ‘blasts’, crowd out normal bone marrow cells and spread into the bloodstream. The ‘blasts’ can also spread to the brain, spinal cord, and other organs.

There are different subtypes of leukemia; a patient who is diagnosed with leukemia should be evaluated by a hematologist/oncologist who will determine the subtype of leukemia and the type of therapy that will be administered to the patient.

The diagnosis is confirmed by obtaining a bone marrow aspirate and biopsy. A bone marrow aspirate and biopsy is a fairly simple procedure to remove a sample of the bone marrow for special testing. Typically it involves putting a needle into the marrow space of the patient’s hip (pelvis) bone and removing bone marrow with a syringe. The marrow sample will be looked at under a microscope; special tests will also be performed on the sample in order to make a specific diagnosis.

Patients who develop cancer should be evaluated and treated by a hematologist/oncologist. Chemotherapy agents (anti-cancer drugs) and other supportive therapies such as blood transfusions are used for the treatment of patients who have cancer. Individuals with Down syndrome are more sensitive to some chemotherapy agents and some of the side effects are more severe for patients with Down syndrome when compared to the general population. Therefore, these patients should be watched more closely when receiving certain types of chemotherapy medicines.

Patients with Down syndrome probably have an increased risk for the development of germ cell tumors (a rare type of cancer found in the ovaries or the testes that may also be found in other areas of the body such as the brain, chest, or abdomen). There is increasing concern that retinoblastoma (a rare type of cancer that develops in the eye, in the cells of the retina) may be diagnosed more frequently among people with Down syndrome. By far the most frequent type of cancer encountered in patients with Down syndrome is leukemia.

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NDSS thanks Dr. Natalia Dixon for preparing this information.