Premium
Alpha‐Thalassaemia Trait in Various Racial Groups in the United Kingdom: Characterization of a Variant of Alpha‐Thalassaemia in Indians *
Author(s) -
Walford Diana M.,
Deacon Rosemary
Publication year - 1976
Publication title -
british journal of haematology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.907
H-Index - 186
eISSN - 1365-2141
pISSN - 0007-1048
DOI - 10.1111/j.1365-2141.1976.tb00190.x
Subject(s) - alpha (finance) , heterozygote advantage , sickle cell trait , red cell , beta thalassaemia , beta (programming language) , medicine , red blood cell , trait , hemoglobinopathy , population , biology , thalassemia , genetics , genotype , hemolytic anemia , gene , surgery , construct validity , disease , environmental health , computer science , patient satisfaction , programming language
SUMMARY. Patients whose red‐cell indices are suggestive of thalassaemia trait, but who have a normal haemoglobin electrophoretic pattern, may be carriers of αthalas‐saemia. A diagnosis of αthalassaemia trait was made in 44 such patients, using the incorporation of [ 3 H]leucine by reticulocytes to measure the relative rates of synthesis of the α and β‐chains of adult haemoglobin. Patients with αthalassaemia trait had a reduced rate of synthesis of the αchains, with a mean α/β specific activity ratio of 0.79 ± SD 0.07. The mean α/β specific activity ratio of 20 control subjects was 1.06 ± SD 0.08. The diagnostic value of the haemoglobin H (Hb H) preparation was assessed in proven αthalassaemia heterozygotes of various races. A high proportion of ‘false negative’results in Indian and Negro heterozygotes indicated that the Hb H preparation is a highly unreliable screening test for use in a multi‐racial population. There was no significant difference in the mean level of Hb A 2 in αthalassaemia heterozygotes (2.0 ± SD 0.6) compared with that of the control group (2.1 ± SD 0.5). Comparison of data from patients with α and β‐thalassaemia traits showed that αthalassaemia trait is the milder disorder, in terms of its effects on red‐cell morphology, red‐cell indices and degree of globin chain imbalance. Amongst individual patients with αthalassaemia trait, there was no correlation between the α/β specific activity ratio and the red‐blood‐cell (RBC) count, mean corpuscular volume (MCV) and mean corpuscular haemoglobin (MCH). This suggests that the α/β ratio cannot be used to distinguish between carriers of a mild gene (‘silent carriers’) and carriers of a more severe disease. This is the first study to characterize αthalassaemia trait in Indians, in whom it appears to be a common disorder. Haematologically, αthalassaemia trait in Indians is milder than that seen in Chinese and the fact that haemoglobin Bart's hydrops fetalis does not occur in Indians makes it likely that the genetics of Indian αthalassaemia differ from those of the Chinese disease. A possible genetic model for Indian αthalassaemia is discussed and the identification of the homozygote is seen as the first step in the determination of the underlying molecular defect.