Trivia: Common Birth Defects/Congenital Disorders – Blood-Related

Definition: Thalassemia patients have abnormal globin chains in their red blood cells, which interferes with the transportation of oxygen through the blood and causes the red blood cells to die easily. The disease is classified into alpha (α), beta (β), and delta (δ) thalassemia, depending on which type of globin chain is affected. Thalassemia is also classified according to the severity of the disease. Patients with thalassemia minor (aka thalassemia trait) have one normal copy of the gene and one gene with thalassemia trait. These patients are generally healthy, although they may suffer mild to moderate anemia. Two parents with thalassemia minor have a one in four chance of having a child with thalassemia major. Patients with thalassemia intermedia have one copy of a milder form of the thalassemia gene and one copy of a severe form of the thalassemia gene. Those with thalassemia major have two copies of the severe form of the thalassemia gene.

Prevalence: According to the 2006 March of Dimes Global Report on Birth Defects, there were 307,897 cases of congenital hemoglobin disorders (thalassemia and sickle cell disease combined) worldwide in 2001. This translates to a prevalence of 2 in 1,000 births. Thalassemia is much more common in Mediterranean, Chinese, South Asian, Middle Eastern, and African populations.

Effects: If left untreated, thalassemia major can cause severe anemia within the first year of life, and bone deformities and death within 10 years. Other symptoms include chronic fatigue, failure to thrive, and organ damage due to the excessive buildup of iron.

Causes: Hereditary.

Treatment: Patients with thalassemia intermedia and thalassemia major generally require regular blood transfusions. They may also need iron chelating drugs to remove the excess iron build-up that is a side-effect of the transfusions. Bone marrow transplants are an option in treating thalassemia major.

Definition: Sickle cell disease includes a group of diseases where the red blood cells produce a mutant form of β hemoglobin called sickle hemoglobin. Sickle cell anemia is the best known example of sickle cell disease.

Prevalence: According to the 2006 March of Dimes Global Report on Birth Defects, there were 307,897 cases of thalassemia and sickle cell disease worldwide in 2001. This translates to a prevalence of 2 in 1,000 births. Sickle cell disease is more common in areas where malaria is, or used to be, prevalent.

Effects: Individuals with sickle cell disease generally fare well, but suffer from periodic sickle cell crises. These crises occur when red blood cells become stuck in blood vessels, and cause ischemia (a restriction in blood supply) or infarction (a blocked artery). Such crises can cause pain and organ damage. Patients with sickle cell disease are also prone to infections and have an average life expectancy of 40 years.

Causes: Hereditary.

Treatment: Regular folic acid supplements and therapies to treat sickle crises when they occur.

Definition: Patients with this disease lack the glucose-6-phosphate dehydrogenase (G6PD) enzyme.

Prevalence: According to the 2006 March of Dimes Global Report on Birth Defects, there were 177,032 cases of neonatal G6PD deficiency worldwide in 2001. This translates to a prevalence of 1 in 1,000 births.

Effects: Patients with G6PD deficiency suffer hemolytic anemia when they are exposed to certain foods (such as broad beans), infections, and certain drugs. Patients are also prone to infections and prolonged neonatal jaundice.

Causes: Hereditary. G6PD is an X-linked, recessive disease. Almost all patients are male, since women who have the G6PD deficiency gene usually have a normal copy of the gene on their second X chromosome.

Treatment: Hemolytic anemia can be prevented by avoiding the foods and drugs that trigger it, and by vaccinating patients against infectious agents. Treatments for hemolysis include blood transfusions and dialysis to treat kidney failure.