Thalassemia
Thalassemia, a group of hereditary hemolytic anemias, is characterized by defective synthesis in one or more of the polypeptide chains (alpha and beta) necessary for hemoglobin production. Structurally, the chains are normal, but the genetic defect decreases their number and can affect either the alpha or beta pair. Because thalassemia affects hemoglobin production, it also impairs red blood cell (RBC) synthesis. This disorder is most common in individuals of Mediterranean ancestry (especially Italians and Greeks), although it also occurs in Blacks and people from southern China, southeast Asia, and India.
Pediatric pointerHydrops fetalis, the most severe form of alpha-thalassemia, causes severe anemia and heart failure. The fetus becomes hydropic, leading to stillbirth or death shortly after birth. Prenatal testing can detect the condition.
Beta-thalassemia is the most common form of this disorder and occurs in three clinical forms: thalassemia major, intermedia, and minor. The severity of the resulting anemia depends on whether the patient is homozygous or heterozygous for the thalassemic trait. The prognosis for beta-thalassemia varies.
Pediatric pointerPatients with thalassemia major seldom survive to adulthood; children with thalassemia intermedia develop normally to adulthood, although puberty is usually delayed; and patients with thalassemia minor can expect a normal life span.
Causes
Thalassemia major and intermedia result from homozygous inheritance of the partially dominant autosomal gene responsible for this trait. Thalassemia minor is caused by heterozygous inheritance of the same gene. Total or partial deficiency of beta polypeptide chain production impairs hemoglobin synthesis and results in continual production of fetal hemoglobin, even after the neonatal period has passed.
Complications
As children with thalassemia major grow older, they become prone to pathologic fractures. This occurs because the bone marrow cavities expand as the long bones thin. Other complications include cardiac arrhythmias, heart failure, and conditions resulting from iron deposits in the heart and other tissues caused by repeated blood transfusions.
Assessment
In thalassemia major (also known as Cooley’s anemia and erythroblastic anemia), the infant, well at birth, develops severe anemia, bone abnormalities, failure to thrive, and life-threatening complications. Often, the first signs are pallor and yellow skin and scleras in infants between ages 3 and 6 months. Later signs are severe anemia, splenomegaly or hepatomegaly with abdominal enlargement, frequent infections, bleeding tendencies, and anorexia.
Children with thalassemia major usually have small bodies and large heads and may also be mentally retarded. Infants may have mongoloid features because bone marrow hyperactivity thickens the bone at the base of the nose.
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