Showing papers on "Hemoglobin A2 published in 1980"

Lack of influence of fetal hemoglobin levels or erythrocyte indices on the severity of sickle cell anemia.

Abstract: A B S T R A C T Persoins with sickle cell anemiiia who have elevated fetal hemoglobin or lowered erythrocyte mean corpuscular volume are reputed to have less severe clinical manifestations anid a greater probability of survival. This study examiines the relationship between seven clinical indicators of morbidity in sickle cell anemia and seven hematological parameters that were collected fromn 214 patients. Risks of sickle cell crisis, acute chest syndromiie, hospital admissions, cerebrovascular accident, aseptic necrosis, meningitis/septicemia, and death were used as indicators of morbidity. The hematological parameters included percent fetal hemoglobin, absolute fetal hemoglobin, percent hemoglobin A2, hemoglobin concentration, packed cell volume, mean corpuscuilar volume, and mean corpuscular hemoglobin concentration. Statistical analyses of the data showed no relationship between the hematological paramiieters and six of the seven clinical indicators of the severity of sickle cell anemia. The only significant finding was an increased risk of stroke in those patients with lower levels of fetal hemnoglobin. Therefore, with this exception, there is no predictable relationship between morbidity and mortality in sickle cell anemia and levels of fetal heimoglobin or erythrocyte indices. Thus, the general belief that there is an association between severity of sickle cell anemia and the levels of fetal hemoglobin has not been established.

Solubilization of hemoglobin S by other hemoglobins

Abstract: The polymerization of mixtures of Hb S with hemoglobins A, A2, and F has been investigated by analysis of the proportions of S and non-S hemoglobin both in the supernate and in the pellet after centrifugation. In all cases the non-S hemoglobin was incorporated into the polymer even in the absence of hybrids in the order A > A2 > F. The solubility of Hb S is substantially increased by the other hemoglobins, especially by Hb F, which would account for its antisickling effect. It appears that the excluded volume effect of the other hemoglobin on Hb S is largely counterbalanced by the solubilizing effect arising from the interaction between the two hemoglobins in solution. The ability of hybrid hemoglobins to gel was demonstrated directly with tetramers in which alpha beta s dimers were covalently linked to alpha beta A, alpha delta A2, and alpha gamma F dimers.

Sickle beta 0 thalassemia in Eastern Saudi Arabia.

Abstract: The sickle cell (beta s) gene occurs at a high frequency in the oasis populations of Eastern Saudi Arabia. However, as compared with the disorder in Africans, sickle cell anemia runs an unusually benign clinical course in this populations; this has been attributed in part to the relatively high levels of fetal hemoglobin (Hb F) which characterize Saudi Arabians with this condition [1, 2]. As yet, there is no satisfactory explanation for this remarkable phenomenon. To learn more about the expression of the beta s gene in Eastern Saudi Arabia, we examined its interaction with beta 0 thalassemia. We found that remarkably high levels of Hb F in this population are not restricted to individuals with sickle cell anemia but also occur in compound heterozygotes for the beta s and beta 0 thalassemia (beta 0 thal) genes. Additionally, this study has characterized sickle cell-beta 0 thalassemia (S-beta 0 thal) in Eastern Saudi Arabia for the first time.

Homozygous Delta Thalassemia in Japan

Abstract: Six families with delta-thalassemia have been found in Japan, in which 10 individuals are delta-thalassemia homozygotes with complete deficiency of Hb A2 and 18 individuals are heterozygotes with low levels of Hb A2. In three families with 10 individuals among these, persistence of fetal hemoglobin of Swiss type was observed. Almost all the members of these families were free from clinical symptoms and hematological abnormalities of the red cells.

Five families with homozygous delta-thalassaemia in Japan.

Abstract: Five families with delta-thalassaemia discovered in Ehime, Japan, are presented. The delta-thalassaemia was associated with a slight elevation of the level of Hb F in two families and with normal Hb F levels in three. Complete absence of HbA2 was found in the homozygous probands. No abnormal clinical or haematological findings were noted in the individuals with delta-thalassaemia.

Haematological characteristics of the beta 0 thalassaemia trait in Sardinian children.

Abstract: We report red cell indices and haemoglobin (Hb)A2 levels in Sardinian children with heterozygous beta 0-thalassaemia and in normal controls aged 6 months to 12 years. Iron-deficient children and those with haematological findings indicative of alpha-thalassaemia were excluded. As in adult carriers, these subjects have significantly increased mean red cell counts and significantly reduced mean Hb levels, mean corpuscular volume (MCV), mean corpuscular haemoglobin (MCH), haematocrit, and mean corpuscular haemoglobin concentration. From 66 to 76% of the heterozygous beta 0 thalassaemia children examined were anaemic. MCH and MCV were within the normal range in 2.8% of these children. Serum ferritin levels showed no difference from those of normal controls.