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Biomedical subjects

A Cao

Publications and source records attributed to A Cao.

At least 253 records · Page 14Linked to original sources
PubMed1984

A genetic combination of silent beta-thalassaemia, high Hb A2 beta-thalassaemia, and single alpha globin gene deletion causing mild thalassaemia intermedia.

This paper reports a Sardinian patient, who was a compound heterozygote for silent beta-thalassaemia and high Hb A2 beta o-thalassaemia with the clinical phenotype of mild thalassaemia intermedia; alpha globin gene mapping showed a single alpha globin gene deletion. The reduced alpha globin chain output resulted in more balanced globin chain synthesis, which in turn accounted for the mild clinical phenotype.

Child↗
PubMed1984

Hemoglobin inclusions in heterozygous alpha-thalassemia according to their alpha-globin genotype.

In this study we have correlated the presence/absence of rare red blood cells with HbH inclusions with the alpha-globin genotype in a group of Sardinian alpha-thalassemia carriers, whose genotype have been defined by alpha-globin gene mapping. We found that the majority of the carriers investigated, including those with the deletion of a single or two alpha-globin genes and those with non-deletion lesions, have rare blood cells with inclusions, with no significant difference in the frequency of positive finding related to the alpha-globin genotype.

Adult↗
PubMed1984

Longitudinal study of a newborn with a combination of deletion and nondeletion alpha-thalassemia-2.

In this study we have characterized by DNA analysis the molecular basis of an alpha-thalassemia condition found in an infant, with 16% Hb Bart's at birth, who developed an hematologic picture similar to the alpha-thalassemia carrier state. Restriction endonuclease analysis and hybridization with alpha and zeta specific probes have provided strong evidence that this patient carries a genetic compound of deletion alpha-thalassemia-2 lesion (-alpha) and a non-deletion defect [(alpha alpha)th] with both alpha-structural genes intact on chromosome 16. He inherited the deletion alpha-thalassemia-2 chromosome (-alpha) from the father and the chromosome with non-deletion alpha-thalassemia defect from the mother. Because the deletion of one, two, or three alpha-globin structural genes is associated with 1-2%, 5-6%, or 25%, Hb Bart's respectively, these findings suggest that the non-deletion chromosome [(alpha alpha)th] contains two alpha-globin structural genes that are less active than a single alpha gene (-alpha).

Child, Preschool↗
PubMed1984

Hemoglobin constitution of double heterozygotes for alpha or beta-thalassemia and Hb J Sardegna.

In this study, we carried out alpha-globin gene mapping in 12 heterozygotes for Hb J Sardegna and in 5 double heterozygotes for this variant and beta-thalassemia. Then, we correlated the Hb pattern with the alpha and beta-globin genotype. In heterozygotes for Hb J Sardegna with a deletion of a single alpha-globin gene (alpha alpha/-alpha) the amount of the abnormal Hb was significantly (p much less than 0.001) higher than in heterozygotes for this variant with a full complement of 4 alpha-globin structural genes (27.5% versus 20.4%). Double heterozygotes for the abnormal hemoglobin and beta-thalassemia with a full complement of 4 alpha-globin structural genes tended to have lower amount of the abnormal Hb than heterozygotes for this variant who do not have beta-thalassemia.

Chromosome Mapping↗
PubMed1984

Developmental pattern of beta-chain production at midtrimester pregnancy in Sardinian beta o-thalassemia heterozygotes.

This study shows a minor, statistically non significant increase, of beta-chain synthesis from 18 to 24 weeks gestation in both normal and beta o-thalassemia heterozygous fetuses with no significant changes in the ratio between the values for the two groups as a function of gestational age. This result indicates that at midtrimester pregnancy the developmental pattern of Hb F to Hb A switching in beta o-thalassemia heterozygotes is similar to that of normal fetuses.

Female↗
PubMed1984

Hematological phenotype of the double heterozygous state for alpha and beta thalassemia.

In this study, we have correlated the hematological phenotype of 56 Sardinian beta o-thalassemia heterozygotes with their alpha-globin genotype as defined by restriction endonuclease mapping. We found that the coinheritance of the deletion of one alpha-globin and, more obviously, two alpha-globin genes tend to normalize the thalassemia-like hematological phenotype commonly associated with the beta o-thalassemia carrier state. On the other hand, the association of the deletion of three alpha-globin genes caused a more severe phenotype. By globin chain synthesis analysis, those beta o-thalassemia heterozygotes with the (-alpha/alpha alpha) alpha-globin genotype had less deficiency of beta-chain synthesis than did those with the normal alpha-globin genotype (alpha alpha/alpha alpha). In heterozygotes with the (-alpha/-alpha) and in those with the (--/-alpha) alpha-globin genotype the imbalance was actually reversed with a mild or marked alpha-chain synthesis excess respectively.

DNA↗
PubMed1983

Prenatal diagnosis of beta-thalassemia. Detection of a single nucleotide mutation in DNA.

We investigated a method employing synthetic oligonucleotides for the prenatal diagnosis of beta-thalassemia due to a single nucleotide mutation. The beta 0 thalassemia we tested is produced by a nonsense mutation and is commonly found in Sardinia and other parts of the Mediterranean. In this DNA lesion, the glutamine codon CAG at the beta 39 position is mutated to TAG, which results in a stop codon and premature termination of the beta-globin chain. We synthesized two oligonucleotides: one homologous to the normal beta A gene and the other to the beta 0 thalassemia gene at the beta 39 location. The oligonucleotides were labeled with 32P and used as hybridization probes for normal and thalassemic DNA. The beta A probe hybridized only to the normal DNA, and the beta-thalassemia probe only to thalassemic DNA, thus providing a technique for direct demonstration of the mutation. The method is sensitive enough to be applied directly to DNA that is isolated from uncultured cells obtained from only 20 ml of amniotic fluid as early as the 16th gestational week.

Amniocentesis↗
PubMed1983

Molecular mechanism accounting for milder types of thalassemia major.

We carried out alpha-globin gene analysis by restriction endonuclease mapping in 91 Sardinians with homozygous transfusion-dependent beta 0-thalassemia and correlated the clinical findings with the alpha-globin genotype. In patients (n = 6) with deletion of two alpha-globin structural genes, disease onset and transfusion dependence occur later than in those (n = 50) with a full complement of alpha-globin genes. There was no statistically significant difference in the group of patients (n = 35) with deletion of only one alpha-globin gene. Patients with deletion of two alpha-globin genes had significantly higher Hb A2 levels than those with a full complement of alpha-structural genes and those with deletion of a single alpha-globin gene. From this and other studies, it seems that the deletion of two alpha-globin structural genes may convert the common severe clinical picture associated with homozygous beta 0-thalassemia to milder forms, ranging from a later occurring but still transfusion-dependent type to a non-transfusion-dependent form.

Child, Preschool↗
PubMed1983

Alpha globin gene analysis in a Sardinian family with interacting alpha and beta thalassaemia genes.

This paper reports the results of alpha globin gene analysis in a Sardinian family with interacting alpha and beta thalassaemia genes. The propositus, who was identified in a newborn survey as he had 26.0% Hb Bart's and 74.0% Hb F, successively developed the clinical and haematological picture of a transfusion-dependent thalassaemia major. According to the haemoglobin pattern, restriction endonuclease analysis of the DNA from this patient showed the deletion of three of the four alpha-globin structural genes. Thus beta 0-thalassaemia homozygotes with the delection of three alpha-structural genes seem to have a severe clinical phenotype similar to that of patients with a full complement of four alpha-globin structural genes.

Chromosome Deletion↗
PubMed1983

Phenotype-genotype correlation in haemoglobin H disease in childhood.

In this study we used restriction endonuclease mapping to characterise the molecular defect responsible for haemoglobin H disease in 14 Sardinian children. The resulting genotypes were then correlated with the respective clinical and haematological phenotypes. We found that patients with the combination of non-deletion alpha(+)-thalassaemia [(alpha alpha)th] and deletion alpha(0)-thalassaemia (-Med) have a more severe phenotype than that resulting from the interaction of deletion alpha(0)-thalassaemia (-Med) and alpha(+)-thalassaemia (-alpha) determinants. Clinically, presentation was earlier and with moderate anaemia or haemolytic crisis, enlargement of the liver and spleen, and thalassaemic bone changes. Haematologically, the anaemia was more severe and there were higher bilirubin levels, reticulocyte counts, Hb H levels, and percentage of red blood cells with inclusion bodies. These results suggest that in those Hb H disease patients with the non-deletion [(alpha alpha)th] determinant, two alpha globin genes produce fewer alpha globin chains than a single alpha globin locus.

Adolescent↗
PubMed1983

Serum ferritin levels in hemoglobin H disease.

This study shows that hemoglobin H disease patients aged between 0.5 and 44 years, usually (27 out of 30) have normal serum ferritin levels according to age. This reconfirms that in this disease there are usually normal iron stores. However, in a few patients (3 out of 30) increased levels were found. This may be due to inappropriate iron medication, transfusions or associated idiopathic hereditary hemocromatosis gene.

Adolescent↗
PubMed1983

Globin gene mapping studies in Sardinian patients homozygous for beta zero Thalassaemia.

The genetic factors responsible for the relatively mild clinical phenotypes of some cases of homozygous beta zero thalassaemia (thalassaemia intermedia) in Sardinia have been evaluated. The frequency of deletion forms of alpha thalassaemia was higher in patients with thalassaemia intermedia (6/8) than in those with thalassaemia major (6/17). The beta globin gene clusters were also studied, first to determine whether there were any rearrangements of the gamma genes, and second to see whether the restriction fragment length polymorphism patterns (haplotypes) of the two groups of patients were similar. The structure of the gamma genes was normal in all the patients with the single exception of a thalassaemia major patient with a triplicated gamma gene arrangement. The beta globin gene cluster haplotypes of the two groups of patients were not significantly different. However, the frequency of the various haplotypes in the thalassaemic as compared to the normal (beta A) chromosomes was different. This finding is of potential value in the antenatal diagnosis of homozygous beta thalassaemia in this population.

Child↗
PubMed1983

Phenotypic effect of heterozygous alpha and beta 0-thalassemia interaction.

In this study, we carried out restriction endonuclease mapping in order to characterize the alpha-globin genotype of 10 Sardinian beta 0-thalassemia heterozygotes, all of whom presented with normal red blood cell indices and increased HbA2 levels. In 8 of these subjects, we found the deletion of two alpha-globin genes (-alpha/-alpha), and in the remaining two the deletion of a single alpha-globin gene (-alpha/alpha alpha). In three of these carriers with the (-alpha/-alpha) alpha-globin genotype and in one with the (-alpha/alpha alpha) genotype, we also found the glucose-6-phosphate dehydrogenase (G6PD) defect of the Mediterranean type. On the basis of these findings, we may conclude that the interaction of heterozygous beta 0-thalassemia with alpha-thalassemia, due to the deletion of either one or two alpha-globin genes, may lead to the production of red blood cells with normal indices. The association of the G6PD defect with this thalassemia gene complex may eventually contribute to this effect. We suggest, therefore, that screening programs for heterozygous beta-thalassemia in populations where alpha-thalassemia is also prevalent, should incorporate the determination of HbA2 in the first set of tests.

DNA↗
PubMed1983

Delta +-thalassemia in Sardinia.

We have defined a new type of delta-thalassemia in which beta-globin chain synthesis is incompletely suppressed. Homozygotes have unusually low HbA2 levels, and double heterozygosity for this delta-thalassemia gene and beta-thalassemia normalizes the HbA2 level. The delta-thalassemia occurs on a chromosome that is identifiable using polymorphic restriction endonuclease sites. We call this condition delta +-thalassemia, to distinguish it from the previously described delta 0-thalassemia syndromes in which no delta-globin chain synthesis occurs.

Chromosome Mapping↗
PubMed1983

A family with segregating triplicated alpha globin loci and beta thalassemia.

In this article we report a Sardinian family, in which a beta-thalassemia gene and a triple alpha-globin loci, counterpart of the rightward deletion type alpha-thalassemia-2, were segregating. The analysis of the genotype-phenotype correlations in the different family members allowed us to give an outline of the manifestations associated with different genotype combinations. The heterozygote for the triple alpha-loci showed no consistent abnormal clinical or hematologic characteristics and presented balanced alpha/beta-globin chain synthesis. In the homozygous state for this lesion, the only phenotypic expression was a slightly imbalanced globin chain synthesis. The combination of heterozygous beta-thalassemia with the heterozygous state for the triple alpha-globin loci produced no clinical manifestations and showed a hematologic phenotype indistinguishable from that of heterozygous beta-thalassemia. On the other hand, the combination of the homozygous state for the triple alpha-globin gene loci and the heterozygous state for beta-thalassemia produced a clinical picture of thalassemia intermedia with a very mild clinical course, minor increase of fetal hemoglobin (HbF) levels, and a pronounced imbalance of globin chain synthesis.

Adult↗