![]() ![]() Rarely, infection with parvovirus B19 can cause an aplastic crisis. Individuals with HbH disease may develop gallstones and experience acute episodes of hemolysis in response to oxidant drugs and infections. The majority of individuals have enlargement of the spleen and less commonly of the liver, mild jaundice, and sometimes mild-to-moderate thalassemia-like skeletal changes (e.g., hypertrophy of the maxilla, bossing of the skull, and prominence of the malar eminences) that affect the facial features. ![]() The phenotype of HbH disease varies however, clinical features are usually only diagnosed during routine hematologic analysis in an asymptomatic individual. Maternal complications during pregnancy commonly include preeclampsia, polyhydramnios or oligohydramnios, antepartum hemorrhage, and premature delivery. Retardation in brain growth, hydrocephalus, cardiovascular deformities, and urogenital defects have been reported.Ī very small number of newborns survive following intrauterine transfusions and repeated frequent transfusions after birth. ![]() Extramedullary erythropoiesis, marked hepatosplenomegaly, and a massive placenta are common. Notably, red cells with Hb Bart have an extremely high oxygen affinity and are incapable of effective oxygen delivery. The main clinical features are generalized edema and pleural and pericardial effusions as a result of congestive heart failure induced by severe anemia. Affected fetuses are either delivered stillborn at 30-40 weeks' gestation or die soon after birth. Hb Bart syndrome is the most severe clinical condition related to α-thalassemia. The severity of the α-thalassemia syndromes depends on the extent of α-globin chain defect (see Genotype-Phenotype Correlations). The clinically significant phenotypes of alpha-thalassemia (α-thalassemia) are hemoglobin Bart hydrops fetalis (Hb Bart) syndrome and hemoglobin H (HbH) disease. Pregnancy management: Complications reported in pregnant women with HbH disease include worsening anemia, preeclampsia, congestive heart failure, and threatened miscarriage monitoring for these issues during pregnancy is recommended. Surveillance: For HbH disease, hematologic evaluation every six to 12 months assessment of growth and development in children every six to 12 months monitoring of iron load with serum ferritin concentration and periodic quantitative measurement of liver iron concentration.Īgents/circumstances to avoid: In persons with HbH disease: inappropriate iron therapy and oxidant drugs (i.e., the same drugs to be avoided by individuals with glucose-6-phosphate dehydrogenase deficiency).Įvaluation of relatives at risk: Test the sibs of a proband as soon as possible after birth for HbH disease so that monitoring can be instituted. Prevention of secondary complications: Monitor individuals with HbH disease for hemolytic/aplastic crisis during febrile episodes in those who require chronic red blood cell transfusions, iron chelation therapy should be instituted for those who are not red blood cell transfusion dependent, iron chelation with deferasirox can be considered to reduce liver iron concentration. However, recent advances in intrauterine and postnatal therapy have increased treatment options, thus complicating the ethical issues for health care providers and families facing an affected pregnancy. Prevention of primary manifestations: Because of the severity of Hb Bart syndrome, the occasional presence of congenital anomalies, and the risk for maternal complications, prenatal testing and early termination of pregnancies at risk have usually been considered. ![]() In contrast, persons with non-deletional HbH disease may be more severely affected and transfusion dependent. Red blood cell transfusions are very rarely needed for severe anemia affecting cardiac function and erythroid expansion that results in severe bone changes and extramedullary erythropoiesis. HbH disease: while most individuals are clinically well and survive without any treatment, occasional red blood cell transfusions may be needed during hemolytic or aplastic crises. Treatment of manifestations: Hb Bart syndrome: intrauterine blood transfusions, improved transfusion strategies, and rarely curative hematopoietic stem cell transplant may allow survival of children. ![]()
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