Cases reported "Thalassemia"

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. These results indicate that in the absence of high HbF determinants, concomitant inheritance of homozygous alpha-thal-2 with homozygous severe beta thal does not influence the severity of the thalassemic phenotype.
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1/18. A G gamma type of the hereditary persistence of fetal hemoglobin with beta chain production in cis.

    In a new subclass of G gamma HPFH which has been detected in a black family, beta A chains are produced in cis to the HPFH determinant (the G gamma-beta HPFH). No other instance of beta chain production in cis to HPFH has been reported. All individuals in this family are well even if Hb S is produced in trans to HPFH. Genetically, this new subclass requires a slightly smaller deletion in the gamma, delta, and beta complex of genes than do other forms of HPFH. It is speculated that a subclass (the G gamma-(G gamma A gamma)-beta HPFH) in which beta S chains are produced in cis to HPFH in conjunction with true beta S genes in trans may be responsible for "mild" cases of sickle cell anemia.
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2/18. Globin chain synthesis in the greek type (A gamma) of hereditary persisitence of fetal haemoglobin.

    Globin chain synthesis was studied in a family with both the Greek (Agamma) type of hereditary persistence of fetal haemoglobin and beta thalassaemia. The ratio of alpha/(gamma beta delta) chain synthesis in the hereditary persistence of fetal haemoglobin (HPFH) heterozygotes was 0.97 while in the HPFH/beta-thalassaemia heterozygote it was 2.14. However, calculation of the amounts of haemoglobin synthesized per cell suggests that in the HPFH/beta-thalassaemia heterozygote, the beta- and Agamma-chain genes in cis to the HPFH determinant are unable to compensate for the deficiency of chains imposed by the beta-thalassaemia gene in trans and that the increased synthesis of Hb F is directed by the gamma-chain genes located on the beta-thalassaemia chromosome. The data suggest that synthesis of beta and Agamma chains in the Greek HPFH is fixed at a 'preset' level and indicate that the defect might be due to an abnormality in the rate of transcription of the closely linked beta-, delta- and gamma-chain genes.
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3/18. Molecular characterization of thalassemia intermedia associated with HPFH-6/beta-thalassemia and HPFH-6/Hb E in Thai patients.

    We report the molecular and hematological characterizations of thalassemia caused by interactions of the hereditary persistence of fetal hemoglobin (HPFH)-6 with beta-thalassemia in 2 Thai patients and the HPFH-6 with Hb E in another Thai patient. Marked hypochromic microcytosis, characteristics of thalassemia intermedia, were obvious in the former 2 cases but the latter had much milder clinical phenotype with normal Hb and a slightly reduced mean corpuscular volume (MCV) value. Hb analysis revealed no Hb A but Hb A(2)F patterns in the compound HPFH-6/beta-thalassemia patients and the EF pattern in the HPFH-6/Hb E patient. The (G)gamma-globin chain predominated in all cases. Globin gene analyses demonstrated that all patients carried the 101-kb HPFH-6 deletion in trans to the beta-thalassemia genes with the IVS1#5 G-C mutation and the G insertion between codons 8/9 and the beta(E)-gene, respectively. Hematologic data of the patients were compared to those of the HPFH-6 heterozygotes found in their family members and different genotype-phenotype interactions of this HPFH determinant in these Thai patients are illustrated.
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4/18. Ggamma -37 (A-->T): a new nondeletional hereditary persistence of fetal hemoglobin determinant associated with the rare codon 91 ( T) delta0-thalassemia.

    We recently described a rare frameshift mutation in the delta-globin gene in a Dutch patient, in association with a new mutation of the Ggamma-globin gene promoter [Ggamma -37 (A-->T)] with a moderately elevated Hb F level of 2.3%. The delta mutation at codon 91 ( T) has been described once before in our laboratory in 1989, in a complex Belgian family with Ggamma (Agammadeltabeta)0-thalassemia (thal) and moderately elevated Hb F levels, without the Ggamma (Agammadeltabeta)0-thal deletion in some individuals. Analysis of the patients from 1989 revealed the presence of the same Ggamma-globin gene mutation and moderately elevated Hb F in all patients, who were also carriers of the delta-globin gene frameshift. Further analysis demonstrated that the two mutations were in linkage with the same haplotype in both the Belgian family and the recently found patient, confirming the association of the elevated Hb F expression with the new Ggamma-globin gene mutation.
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5/18. Intrinsic potential for high fetal hemoglobin production in a Druz family with beta-thalassemia is due to an unlinked genetic determinant.

    The mechanism for elevated production of fetal hemoglobin (Hb F) in a Druze patient with beta zero-thalassemia intermedia was investigated. Heterozygous family members exhibited normal Hb F levels, suggesting that the increase in gamma-gene expression in the propositus may be partly due to anemic stress. Erythroid progenitors of these family members cultured in vitro [burst forming units (erythroid); (BFUe)] showed elevated synthesis of Hb F, indicating the existence of a genetically determined intrinsic capacity for high Hb F production in this family. The propositus was found to be homozygous for a IVS2-position 1 mutation, on the background of Mediterranean haplotype I, which is not known to be linked to high Hb F production. Moreover, extensive molecular studies of the beta-globin gene cluster, including sequence analysis of the promoter regions of the gamma-globin genes, did not reveal any cis- actin mechanism that could account for the high Hb F production in the propositus. A young niece of the propositus with beta zero-thalassemia major was recently discovered, who was homozygous for the same beta-globin allele and haplotype as the propositus. However, unlike her uncle, she does not have a high Hb F level and presents with a severe clinical course. Her inability to produce high Hb F suggests that the genetic determinant for increased gamma-gene expression in the propositus is unlinked to the beta-globin gene cluster.
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6/18. Interaction of two different disorders in the beta-globin gene cluster associated with an increased hemoglobin F production: a novel deletion type of (G) gamma ((A) gamma delta beta)(0)-thalassemia and a delta(0)-hereditary persistence of fetal hemoglobin determinant.

    We report two different disorders of the beta-globin gene cluster segregating in a Belgian family: a novel deletion that results in (G) gamma ((A) gamma delta beta)(0)-thalassemia (thal) and a heterocellular hereditary persistence of foetal hemoglobin of the Swiss type linked to a delta(0)-thal gene (delta (0)-HPFH). Heterozygosity for the heterocellular HPFH brings about a moderate (3.4% to 8.24%) increase of hemoglobin (Hb) F having a G gamma/A gamma ratio of 4:1, whereas carriers of the G gamma ((A) gamma delta beta)(0)-thal deletion show in their peripheral blood a considerably higher (15%) percentage of Hb F. Both defects interact in the compound heterozygotes for G gamma ((A) gamma delta beta)(0)-thal and delta(0)-HPFH producing a further increase (up to 24%) of fetal Hb consisting entirely of G gamma chains. Molecular characterization of the (G) gamma ((A) gamma delta beta)(0)-thal by means of Southern analysis showed that the deletion spans about 50 kb, removing the 3' end of the A gamma-gene, the psi beta-, delta-, and beta-genes. A number of possible mechanisms leading to the overproduction of Hb F in HPFH and (G) gamma ((A) gamma delta beta)(0)-thal will be discussed.
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7/18. alpha-thalassemia resulting from deletion of regulatory sequences far upstream of the alpha-globin structural genes.

    We describe an alpha-thalassemia determinant in which alpha-globin expression is silenced by a deletion located 27 kb 5' to the transcription start site of the alpha 2-globin gene. This alpha-thalassemic determinant, (alpha alpha)MM, is a member of a newly described group of thalassemic mutations resulting from deletion of locus-controlling sequences critical to globin gene expression.
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8/18. Concomitant inheritance of homozygous alpha-thalassemia-2 with homozygous IVS-I-5 G-C beta gene mutation does not influence the severity of the thalassemic phenotype.

    An Asian Indian child presented the severe transfusion dependent form of beta-thalassemia major. Sequencing data and gene mapping analysis revealed the concomitant presence of homozygous alpha-thal-2 type 3.7 kb deletion with homozygous beta thal IVS-1-5 G-C mutation. Further studies at the dna level demonstrated that he was XmnI negative at the -158 G gamma site and had the haplotype

9/18. Unusual molecular basis of Hb H disease in the azores islands, portugal.

    An Azorean family with Hb H disease (10% Hb H) was studied in order to elucidate its molecular basis. dna studies on the patient only revealed a 4.2 kb "leftward" deletion of paternal origin which implies the co-inheritance of a nondeletional alpha-thalassemia determinant. Restriction endonuclease and oligonucleotide analysis allowed the exclusion of five point mutations: initiation codon (at both alpha 1- and alpha 2-globin genes), IVS-I donor splice junction pentanucleotide deletion, codon 125 CTG   CCG substitution, and Saudi Arabian polyadenylation signal mutation. These findings suggest that the molecular basis of this form of Hb H disease is probably different from those described previously.
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10/18. Alpha thalassaemia in two Spanish families.

    Two Spanish families with alpha thalassaemia, including 4 individuals with Hb H disease, are described. dna mapping shows that, in addition to the common alpha thalassaemia determinant (-alpha 3.7), a different and previously unreported allele is present in each family. In one, there is a deletion of 10.5-12 kb of dna including both alpha genes (--SPAN). In the other, a deletion of more than 100 kb has removed the entire alpha globin gene complex (--BR).
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