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Results for “Alpha-thalassaemia”

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At least 19 recordsLinked to original sources
PubMed2026

Alpha-thalassaemia early eluting peak for alpha-thalassaemia --SEA carrier screening: a multicentre diagnostic comparison with immunochromatographic strip test and haemoglobin H inclusion test.

While high-performance liquid chromatography (HPLC) is well-established for &#x3b2;-thalassaemia and haemoglobinopathies, phenotypic screening for &#x3b1;0-thalassaemia has been limited. To address this limitation, we aimed to translate the discovery of the &#x3b1;-thalassemia early eluting peak (&#x3b1;EEP) in HPLC into clinical practice by comparing its diagnostic performance with other existing methods (haemoglobin H inclusion test [HbHi] and immunochromatographic strip test [ICT]) in a multicentre setting, and elucidating the nature of the &#x3b1;EEP by liquid chromatography-tandem mass spectrometry (LC-MS/MS). With a cohort of 820 genotyped patients, the &#x3b1;EEP showed superior diagnostic performance in detecting --SEA (sensitivity 99.6%, specificity 100%) compared with HbHi (sensitivity 95.8%, P&#x2009;=&#x2009;0.006; specificity 97.3%, P&#x2009;<&#x2009;0.001) and ICT (sensitivity 95.8%, P&#x2009;=&#x2009;0.006; specificity 75.4%, P&#x2009;<&#x2009;0.001). Both HbHi and ICT showed reduced sensitivity in &#x3b2;-thalassaemia carriers versus non-carriers. ICT showed reduced specificity when Hb F&#x2009;&#x2265;&#x2009;1% compared with <&#x2009;1%. The &#x3b1;EEP remained robust across all subgroups. LC-MS/MS revealed a strong association between the &#x3b1;EEP and embryonic &#x3b6;-globin chains (P&#x2009;<&#x2009;0.001). The &#x3b1;EEP offered cost reductions of 98.6% over HbHi and 97.3% over ICT. Collectively, the &#x3b1;EEP is a highly reliable and cost-effective marker for detecting --SEA carriers, enabling a novel "all-in-one" HPLC screening strategy for --SEA, &#x3b2;-thalassaemia and haemoglobinopathies. Trial registration number: not applicable.

Humans↗
PubMed1978

Interaction between iron deficiency and alpha-thalassaemia: the in vitro effect of haemin on alpha-chain synthesis.

Two conditions are liable to lower the alpha:beta globin biosynthesis ratio in reticulocytes: iron deficiency and alpha-thalassaemia. The present paper studies the effect of haemin on reticulocytes from 12 patients who have alpha-thalassaemia and/or are iron deficient. The alpha:beta globin biosynthesis ratio was improved in all these cases. 4 showed initially an alpha:beta synthesis ratio usually associated with alpha-thalassaemia type-1; on the addition of haemin the ratio rose to that associated with alpha-thalassaemia type-2. In the other 8 patients the ratio was initially typical for alpha-thalassaemia type-2, and on addition of haemin the ratio became normal. It is suggested that in iron deficient patients a diagnosis of alpha-thalassaemia type-1 or type-2 cannot be made unless haemin has been added to the test system. If this is not done iron deficiency alone can cause the alpha:beta globin synthesis ratio to resemble that associated with alpha-thalassaemia type-2, and iron deficiency in combination with alpha-thalassaemia type-2 can cause the ratio to resemble that typical for alpha-thalassaemia type-1. Reticulocytes from 8 alpha-thalassaemic patients without iron deficiency did not show a marked haemin effect (less than 5%), and in 1 patient with iron overload, the ratio actually fell by about 10%.

Adolescent↗
PubMed1979

Negro alpha-thalassaemia is caused by deletion of a single alpha-globin gene.

Studies in two Jamaican Negro families, including haematological and haemoglobin analysis, haemoglobin synthesis, and globin messenger-RNA assay, have defined two alpha-thalassaemia phenotypes which resemble the severe (alpha-thalassaemia 1) and mild (alpha-thalassaemia 2) forms of the disorder described in Orientals. Genetic analysis suggests that subjects with the alpha-thalassaemia-1 phenotype are homozygous for the alpha-thalassaemia-2 determinant. Restriction-endonuclease mapping shows that alpha-thalassaemia-2 results from the deletion of one of the linked pair of alpha-chain genes. Hence the genotypes of the alpha-thalassaemia heterozygotes and homozygotes in these families are -alpha/alpha alpha and -alpha/-alpha respectively. If these are the usual alpha-thalassaemia genotypes in Negroes, these findings explain the difference in clinical expression of the disorder between Orientals and Negroes--in particular, the absence of haemoglobin Bart's hydrops and the rarity of haemoglobin-H disease in Negroes.

Black People↗
PubMed1979

Alpha-thalassaemia in Cyprus.

The frequency of alpha-thalassaemia in Cyprus was determined with studies of haemoglobin Bart's in 1200 Greek Cypriot and 132 Turkish Cypriot newborn babies. Of the Greek newborns, 12.4%, and of the Turkish newborns, 6.8% had raised Hb Bart's (from 0.6% to 12.9% of the total haemoglobin) suggesting that they were carriers of either alpha-thalassaemia-1 or alpha-thalassaemia-2 genes. The findings suggest that the population of Cyprus has the highest frequencies of alpha-thalassaemia among Caucasian people.

Child, Preschool↗
PubMed1975

The alpha-chain-termination mutants and their relation to the alpha-thalassaemias.

The structure, synthesis, genetic transmission, clinical associations and distribution of the elongated alpha-chain haemoglobin variants has been described. The data indicate that the most likely molecular basis for these common abnormal haemoglobins is a single base substitution in the alpha-chain termination codon. Because these variants are produced inefficiently they give rise to the clinical picture of alpha-thalassaemia. When these findings are taken together with recent work regarding the molecular basis for other forms of alpha-thalassaemia it is possible to build up a fairly complete picture of the molecular pathology of the alpha-thalassaemias.

Amino Acids↗
PubMed1979

Interaction between beta-thalassaemia and Hb G Philadelphia associated with alpha-thalassaemia.

A man who did not produce and beta-chains did not suffer from a severe beta-thalassaemia. He was heterozygous for Hb G Philadelphia. It has been suggested that this haemoglobin variant was associated with alpha-thalassaemia and that interaction between alpha-thalassaemia and beta-thalassaemia decreased the imbalance of alpha/beta-globin biosynthesis and thereby the severity of the beta-thalassaemic disorder. Association of Hb G Philadelphia and alpha-thalassaemia in this man and his family is now demonstrated using bone marrow and reticulocytes of the propositus and one of his sons and reticulocytes only of another son.

Bone Marrow↗
PubMed1977

Interaction of haemoglobin E with alpha-thalassaemia and haemoglobin Constant Spring.

The combination of Hb E,alpha-thalassaemia and Hb CoSp was found in a 20-year-old female Malay who presented with a moderately severe haemolytic anaemia. The findings in the patient and her family from which this diagnosis was arrived at are discussed. Although this is the first report of this condition in this country it is pointed out that one may see more such cases in the future if one is aware of this condition since Hb E, alpha-thalassaemia and Hb CoSp all occur at significant frequencies in this country.

Adult↗
PubMed1979

Haemoglobin Bart's hydrops fetalis syndrome in an infant of Greek origin and prenatal diagnosis of alpha-thalassaemia.

An unusual case of Bart's hydrops fetalis is reported where the patient was born to parents of Greek origin. An exchange transfusion was given. Adult haemoglobin (HbA) was present in addition to HbBart's and HbPortland. A low level of synthesis of alpha-chains was evident. The mother presented again in a subsequent pregnancy for prenatal diagnosis of thalassaemia. The fetus was diagnosed as an alpha-thalassaemia carrier, a diagnosis which was confirmed at birth. The nature of alpha-thalassaemia in the family is discussed.

Australia↗
PubMed1978

Leg ulcers in alpha-thalassaemia (haemoglobin H disease).

A case of recurrent leg ulceration associated with alpha-thalassaemia (haemoglobin H disease) is reported. It is suggested that leg ulcers occurring in the thalassaemic syndromes may be due to structural changes in the affected red cells which result in increased cell rigidity, decreased deformability and consequent diminished blood flow in capillary beds that are subjected to venous stasis.

Adult↗
PubMed1978

A unique thalassaemic syndrome: homozygous alpha-thalassaemia + homozygous beta-thalassaemia.

The disturbed balance of globin chain synthesis is a major factor in the pathophysiology of the thalassaemic disorders; this concept is strongly supported by the study of a patient displaying an extreme but symmetrical deficit of both major types of chains alpha and beta. The patient had a mild clinical picture but presented a striking hypochromia (MCH 10 pg) with compensatory erythrocytosis (RBC 10(12)/l.). Study of the propositus and his family by haematological, biochemical and biosynthetic techniques indicates that the patient carries two alpha- and two beta-thalassaemia genes resulting in balanced globin chain synthesis; in addition, several members of the family carry two or three abnormal genes. During observation a change in the haematological pattern occurred with a shift towards more intensive beta-chain and away from gamma-chaim synthesis; this appeared with be associated with improvement of his anaemia through more effective erythropoiesis.

Adult↗
PubMed1979

Haemoglobin Barts in newborn Tanzanians.

Using both starch gel and cellulose-acetate electrophoresis is screening procedures, haemoglobin (Hb) Barts was detected in 11.08% of 325 cord blood samples from newborn Tanzanians. Red cell studies in these and in normals and a search for inclusion bodies of Hb H did not suggest alpha-thalassaemia. The mothers of these babies do not show any evidence of alpha-thalassaemia. It is suggested that the presence of Hb Barts in samples of cord blood is not due to the presence of alpha-thalassaemia in the Tanzanian population.

Adult↗
PubMed1979

Quantitative studies of Hb Bart's levels and red cell indices in alpha thalassaemia trait in Mediterraneans.

Haemoglobin Bart's was detected and quantitated in 42 babies during a survey of cord blood from neonates of Mediterranean origin. The distribution of Hb Bart's levels for the group appeared to be bi-modal, with modes at 2.0% and 5.5%. Haematological data obtained from 21 babies during the first week of life showed a highly significant reduction in average MCV (86.3 +/- 7.7 fl) and MCH (27.8 +/- 6.0 pg) in comparison with a control group of babies. However, there was no significant correlation between these parameters and Hb Bart's levels. Haematological data were available on 57 parents of the Hb Bart's babies and HbH preparations were positive in 28 cases (49%). Examination of red cell indices showed a highly significant reduction in the average MCV and MCH of parents with positive HbH preparations, and a diagnosis of alpha-thalassaemia (based on the presence of HbH inclusion bodies and reductions in MCV and/or MCH) was made in at least one parent in the majority of couples with both partners tested, suggesting that alpha-thalassaemia trait in people of Mediterranean origin is generally associated with detectable haematological changes.

Cyprus↗
PubMed1977

Alpha-beta thalassaemia.

In a Greek Cypriot family in which genes for both alpha and beta thalassaemias were expressed, haematological and biosynthetic investigations indicated that one family member was homozygous for beta thalassaemia and had alpha-thalassaemia1 trait. The concurrent inheritance of an alpha-thalassaemia gene in the beta-thalassaemia homozygote seemed to have modified his degree of chain imbalance and to have reduced the clinical severity of the disease.

Adult↗
PubMed1979

Abnormal haemoglobins in the Sudan savanna of Nigeria. I. Prevalence of haemoglobins and relationships between sickle cell trait, malaria and survival.

The prevalence of different haemoglobins and their interaction with malaria have been studied in Garki, Kano State, Nigeria. Sickle cell trait was present in 24% of newborn and 29% of those aged over five years. Hb.AC was present in 0.7%. Frequency of both haemoglobin variants was greater in Hausa than Fulani. Sickle cell anaemia was almost invariably fatal in early childhood. The distribution curve of percentage of Hb.S in sickle cell trait subjects was normal, and did not demonstrate any high frequency of a gene for alpha-thalassaemia. The presence of beta-thalassaemia minor could not be tested, but Hb.S/beta-thalassaemia was not detected. Hb.S gene frequency appears to have been maintained by a fitness in heterozygotes of 21% over normal homozygotes; increased fertility and high mutation rate did not make any apparent contribution. Hb.AS subjects had on average lower frequency and considerably lower densities of Plasmodium falciparum trophozoites than Hb.AA from the age of 30 to 59 weeks; density was less in sickle cell trait up to age three years in the dry season only. It is suggested that the survival advantage and hence the prevalence of sickle cell trait may be greatest in some hyperendemic areas and less where malaria transmission is extremely high or when it is high and unvaried.

Adolescent↗
PubMed1979

Ocular findings in a case of haemoglobin H disease.

A case is reported of a patient with known haemoglobin H disease who was found to have angioid streaks and retinal detachment. Angioid streaks have not previously been reported in cases of alpha-thalassaemia, and the question whether this is a chance association or otherwise is discussed.

Adult↗
PubMed1979

Hb Bart's and its significance in the South African Negro.

The haematological indices of cord bloods from 430 South African Negro babies were determined by electronic cell counting and their haemoglobin (Hb) patterns examined by alkaline cellulose acetate electrophoresis. A fast-moving, anodal band, identified as Hb Bart's, was found in 7 (1,6%) of the specimens, this being the lowest incidence of the variant yet found in an indigenous African population. The levels of Hb Bart's ranged from 1.3 to 5.5% of the haemoglobin. These findings were confirmed by alkaline-starch gel electrophoresis and at the same time absence of the slow-moving haemoglobin, Hb Constant Spring was established. Subsequent follow-up of 4 of the infants at 4 months of postnatal life showed that the abnormal component had disappeared. The babies with Hb Bart's had a marked microcytosis and low mean corpuscular haemoglobin levels whilst their parents showed no haematological or electrophoretic signs of alpha-thalassaemia. The significance of these findings is discussed in the light of previously reported studies on various Negro groups.

Adult↗