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Fetal hemoglobin, or foetal haemoglobin (also hemoglobin F, HbF, or α 2 γ 2) is the main oxygen carrier protein in the human fetus.Hemoglobin F is found in fetal red blood cells, and is involved in transporting oxygen from the mother's bloodstream to organs and tissues in the fetus.
Hemoglobin variants occur when there are mutations in specific genes that code for the protein chains, known as globins, which make up the hemoglobin molecule. This leads to amino acid substitutions in the hemoglobin molecule that could affect the structure, properties, and/or the stability of the hemoglobin molecule.
Polycythemia is defined as serum hematocrit (Hct) or hemoglobin (HgB) exceeding normal ranges expected for age and sex, typically Hct >49% in healthy adult men and >48% in women, or HgB >16.5 g/dL in men or >16.0 g/dL in women. [8] The definition is different for neonates and varies by age in children. [9] [10]
Normal levels of hemoglobin vary according to sex and age in the range 9.5 to 17.2 grams of hemoglobin in every deciliter of blood. [6] Hemoglobin also transports other gases. It carries off some of the body's respiratory carbon dioxide (about 20–25% of the total) [7] as carbaminohemoglobin, in which CO 2 binds to the heme protein.
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.
Children: 11 to 16 g/dL (110 to 160 g/L, or 6.83 to 9.93 mmol/L) Pregnant women: 11 to 14 g/dL (110 to 140 g/L, or 6.83 to 8.69 mmol/L) (9.5 to 15 usual value during pregnancy) [93] [b] Normal values of hemoglobin in the 1st and 3rd trimesters of pregnant women must be at least 11 g/dL and at least 10.5 g/dL during the 2nd trimester. [95]
In persons with sickle cell disease, high levels of fetal hemoglobin as found in a newborn or as found abnormally in persons with hereditary persistence of fetal hemoglobin, the HbF causes the sickle cell disease to be less severe. In essence the HbF inhibits polymerization of HbS. A similar mechanism occurs with persons who have sickle cell trait.
The hemoglobin was named hemoglobin III, [24] but hemoglobin C was eventually used. [ 25 ] [ 26 ] By 1954, it was found that the mutant hemoglobin was highly prevalent in West Africa. [ 27 ] [ 28 ] In 1960, Vernon Ingram and J. A. Hunt at the University of Cambridge discovered that the mutation was a single amino acid replacement of glutamic ...