alpha thalassemia

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α thal·as·se·mi·a

thalassemia due to one of two or more genes that depress (severely or moderately) synthesis of α-globin chains by the chromosome with the abnormal gene. Heterozygous state: severe type, thalassemia minor with 5-15% of Hb Bart at birth, only traces of Hb Bart in adult; mild type, 1-2% of Hb Bart at birth, not detectable in adult. Homozygous state: severe type, erythroblastosis fetalis and fetal death, only Hb Bart and Hb H present; mild type not clinically defined.
See also: hemoglobin H.
References in periodicals archive ?
In alpha thalassemia, alpha globin expression is deficient and there is a corresponding excess of beta globin chains.
Results: Co-inheritance of alpha thalassemia (-a3.7, -a4.2) with homozygous beta thalassemia was detected in 30% cases of studied cohort (37 out of 121).
In the mid-western region, the migratory target home of Brazilians from several regions of the country, a sample of 404 individuals from 55 cities in the state of Goias revealed a 10.1% prevalence of hereditary anemia, thalassemia and hemoglobin variants, specifically 5.2% of heterozygous alpha thalassemia, 2.2% of hemoglobin S heterozygosity (HbAS); 1% heterozygosity for hemoglobin C (HbAC); 0.7% of lower beta thalassemia; 0.5% alpha-thalassemia and heterozygous for HbS; 0.3% alpha-thalassemia and heterozygous for HbC; and 0.3% heterozygous for hemoglobin D (HbAD) (MELO-REIS et al., 2006).
frequency of alpha thalassemia in Pakistani population as screened through cation exchange chromatography.
A 49-year-old African-American male with a past medical history of the alpha thalassemia trait who had a three-year history of marginal zone monocytoid B-cell non-Hodgkin lymphoma (NHL), which was diagnosed on a lymph node and bone marrow biopsies, had a longstanding splenomegaly with symptoms of fever, night sweats, fatigue, weight loss, mild abdominal pain, and early satiety.
Alpha thalassemia is a reduction or absence of alpha chains ..
We report of an Iranian family with history of a rare haemoglobin variant, Haemoglobin J associated with alpha thalassemia, discovered while performing premarital thalassemia screening.
The prevalence of sickle cell anemia, beta-thalassemia major, beta thalassemia, alpha thalassemia, alpha thalassemia trait was found 0.35% (n=631), 0.07% (n=132), 0.06 % (n=118), 0.005% (n=9), 0.08% (n=150), respectively.
It is estimated, however, that 15% of African Americans (the US population with the highest incidence of any form of thalassemia) are affected by alpha thalassemia. (14) The incidence of beta thalassemia among Mediterranean, African, and Middle Eastern populations ranges from about 5% to 25%.
* Alpha thalassemia occurs when a gene or genes related to the alpha globin protein are missing or changed (mutated).
Neither Hb Rambam (also known as Hb J-Cambridge) a Gly69Asp substitution (28), nor Hb Kenitra, a beta 69 Gly>Arg change associated with an alpha thalassemia show abnormal hematological parameters attributed to the [beta]69 substitution (29).