LP16418-3

Hemoglobin Barts

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Descriptions

Hemoglobin Barts is a relatively common hemoglobin variant consisting of four gamma chains. Hemoglobin Barts is an extremely high affinity hemoglobin that is not effective at delivering oxygen to tissues. Hemoglobin Barts is only seen during the newborn period and usually indicates that one or more of the baby's alpha-globin genes are deleted, resulting in alpha-thalassemia. Alpha thalassemia is caused by deletions of the alpha globin genes on chromosome 16. Normal patients have four copies of the alpha-globin gene, 2 on each chromosome. A silent carrier will have one deleted alpha gene and usually result in a benign condition. Alpha thalassmia trait occurs when there are two deleted alpha genes, resulting in mild or no anemia with microcytosis and hypochromia. Hemoglobin H disease results from the deletion of three alpha genes with resultant moderately severe alpha thalassemia. Most patients are anemic and display some degree of splenomegaly. Fetal hydrops syndrome occurs when all four alpha genes are deleted. Fetal hydrops is not compatible with life and death occurs in utero or during early infancy.Carrier states for alpha thalassemia are very common in the African, Meditteranean and Asian populations. In general, only the loss of one or two genes is seen in African Americans. Asian and Meditteranean populations may have all types of alpha thalassemia. Information from The Georgia Comphensive Sickle Cell Center at Grady Health System, Emory University School of Medicine Department of Pediatrics, Atlanta, GA at www.scinfo.org, accessed 2007 11 02, and The Utah Department of Health at www.health.utah.gov, accessed 2007 11 02. Source: Regenstrief Institute

Hemoglobin Barts consists of four gamma chains. It is moderately insoluble, and therefore accumulates in the red blood cells. It has an extremely high affinity for oxygen, resulting in almost no oxygen delivery to the tissues. It is produced in the disease alpha-thalassemia and in the most severe of cases, it is the only form of haemoglobin in circulation. In this situation, a fetus will develop hydrops fetalis and normally die before or shortly after birth, unless intrauterine blood transfusion is performed.

Since Hemoglobin Barts is elevated in alpha thalassaemia, it can be measured, providing a useful screening test for this disease in some populations. Copyright Text is available under the Creative Commons Attribution/Share-Alike License. See http://creativecommons.org/licenses/by-sa/3.0/ for details. Source: Wikipedia, Wikipedia

Basic Part Properties

Part Display Name

Hemoglobin Barts

Part Type

Component (Describes the core component or analyte measured)

Created On

2000-05-04

Construct for LOINC Short Name

Hgb Barts

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