Hemoglobin H

	Hemoglobin H Hemoglobin H disease is a type of alpha thalassemia caused by impaired production of three of the four alpha globins, coded by genes HBA1 and HBA2. See also * Hemoglobin Barts Hemoglobin Barts, abbreviated Hb Barts, is an abnormal type of hemoglobin that consists of four gamma globins. It is moderately insoluble, and therefore accumulates in the red blood cells. Hb Barts has an extremely high affinity for oxygen, so it ... References External links Blood disorders {{Circulatory-disease-stub ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu]
picture info	Alpha-thalassemia Alpha-thalassemia (α-thalassemia, α-thalassaemia) is a form of thalassemia involving the genes ''HBA1'' and ''HBA2''. Thalassemias are a group of inherited blood conditions which result in the impaired production of hemoglobin, the molecule that carries oxygen in the blood. Normal hemoglobin consists of two alpha chains and two beta chains; in alpha-thalassemia, there is a quantitative decrease in the amount of alpha chains, resulting in fewer normal hemoglobin molecules. Furthermore, alpha-thalassemia leads to the production of unstable beta globin molecules which cause increased red blood cell destruction. The degree of impairment is based on which clinical phenotype is present (how many genes are affected). Signs and symptoms The presentation of individuals with alpha-thalassemia consists of: Cause Alpha-thalassemias are most commonly inherited in a Mendelian recessive manner. They are also associated with deletions of chromosome 16p. Alpha thalassemia can also be acqu ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu]
	Hemoglobin, Alpha 1 Hemoglobin subunit alpha, Hemoglobin, alpha 1, is a hemoglobin protein that in humans is encoded by the ''HBA1'' gene. Gene The human alpha globin gene cluster located on chromosome 16 spans about 30 kb and includes seven loci: 5'- zeta - pseudozeta - mu - pseudoalpha-1 - alpha-2 - alpha-1 - theta - 3'. The alpha-2 (HBA2) and alpha-1 (HBA1; this gene) coding sequences are identical. These genes differ slightly over the 5' untranslated regions and the introns, but they differ significantly over the 3' untranslated regions. Protein Two alpha chains plus two beta chains constitute HbA, which in normal adult life comprises about 97% of the total hemoglobin; alpha chains combine with delta chains to constitute HbA-2, which with fetal hemoglobin (HbF) makes up the remaining 3% of adult hemoglobin. Clinical significance Alpha thalassemias result from deletions of each of the alpha genes as well as deletions of both HBA2 and HBA1; some nondeletion alpha thalassemias have also ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu]
	Hemoglobin, Alpha 2 Hemoglobin, alpha 2 also known as HBA2 is a gene that in humans codes for the alpha globin chain of hemoglobin. Function The human alpha globin gene cluster is located on chromosome 16 and spans about 30 kb, including seven alpha like globin genes and pseudogenes: 5'- HBZ - HBZP1 - HBM - HBAP1 - HBA2 - HBA1 - HBQ1 -3'. The HBA2 (α2) and HBA1 (α1) coding sequences are identical. These genes differ slightly over the 5' untranslated regions and the introns, but they differ significantly over the 3' untranslated regions. Protein Two alpha chains plus two beta chains constitute HbA, which in normal adult life comprises about 97% of the total hemoglobin; alpha chains combine with delta chains to constitute HbA-2, which with HbF (fetal hemoglobin) makes up the remaining 3% of adult hemoglobin. Clinical significance Alpha-thalassemias most commonly result from deletions of any of the four alpha alleles, although some alpha thalassemias have been reported that are due to m ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu]
	Hemoglobin Barts Hemoglobin Barts, abbreviated Hb Barts, is an abnormal type of hemoglobin that consists of four gamma globins. It is moderately insoluble, and therefore accumulates in the red blood cells. Hb Barts has an extremely high affinity for oxygen, so it cannot release oxygen to the tissue. Therefore, this makes it an inefficient oxygen carrier. As an embryo develops, it begins to produce alpha-globins at weeks 5–6 of development. When both of the HBA1 and HBA2 genes which code for alpha globins becomes dysfunctional, the affected fetuses will have difficulty in synthesizing a functional hemoglobin. As a result, gamma chains will accumulate and form four gamma globins. These gamma globins bind to form hemoglobin Barts. It is produced in the disease alpha-thalassemia and in the most severe of cases, it is the only form of hemoglobin in circulation. In this situation, a fetus will develop hydrops fetalis and normally die before or shortly after birth, unless intrauterine blood transfusion ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu]