1/17. A case of beta-thalassemia with a CT substitution at position 654 of the second intervening sequence of the beta-globin gene. A 26-year-old Chinese-Malaysian female patient with beta-thalassemia is presented. The main hematological values found in this patient were as follows: 1) normocytic hypochromic anemia (RBC 444 x 10(4)/microliters, Hb 11.8 g/dl) with marked anisopoikilocytosis, 2) erythroid hyperplasia, and 3) increased HbF (HbA 41.4%, HbA2 2.9%, HbF 48.9%). dna obtained from peripheral leukocytes was analyzed using dot blot hybridization of the polymerase chain reaction (PCR)-amplified dna with allele-specific oligonucleotide probes. A C T substitution at position 654 of the second intervening sequence (IVS-2) was detected in her beta-globin clone.- - - - - - - - - - ranking = 1keywords = hybridization (Clic here for more details about this article) |
2/17. Detection of the Hb Quong Sze mutation in a Chinese family by selective amplification of the alpha 2-globin gene and restriction map analysis with Msp I.The polymerase chain reaction technique combined with restriction map analysis with Msp I and hybridization with synthetic oligonucleotide probes has been used to identify Hb Quong Sze [alpha 125(H8)Leu Pro] in a Chinese family in Guangxi (Quong Sze), P. R. china. Our data and those described in an earlier publication (1) indicate that the Hb Quong Sze carriers originate from the same province of the People's Republic of china, namely Guangxi.- - - - - - - - - - ranking = 1keywords = hybridization (Clic here for more details about this article) |
3/17. A new beta-thalassaemia frameshift mutation detected by PCR after selective hybridization to immobilized oligonucleotides.A previously undescribed mutation (-1, 3, codon 24) causing beta-thalassaemia was identified in an Egyptian patient. It consists in the concomitant deletion of a G in codon 24 and its replacement with the new trinucleotide CAC, thus resulting in the shift of the beta-globin reading frame. The sequence of the chromosome of interest was isolated from the homologous one by means of selective hybridization to an immobilized oligonucleotide. The presence of this mutation in the proband's family was confirmed by dot blot hybridization with an oligonucleotide probe.- - - - - - - - - - ranking = 6keywords = hybridization (Clic here for more details about this article) |
4/17. alpha-thalassemia: prenatal diagnosis and neonatal implications.Homozygous alpha-thalassemia major, or Bart's hemoglobinopathy, is the most common etiology of nonimmune hydrops in those of Oriental descent. The prenatal diagnosis can now be made utilizing dna hybridization technique from fetal cells obtained by either amniocentesis or chorionic villus sampling. A case is reviewed documenting the utilization of dna studies in managing patients known or suspected to have a history of alpha-thalassemia major.- - - - - - - - - - ranking = 1keywords = hybridization (Clic here for more details about this article) |
5/17. Hb Icaria-Hb H disease: identification of the Hb Icaria mutation through analysis of amplified dna.Hb Icaria-Hb H disease was observed in a Yugoslavian teenager who exhibited moderate anaemia with severe microcytosis and hypochromia and 16% Hb H. Four of his relatives were Hb Icaria heterozygotes; their haematological data were comparable to those with a deletional type of alpha-thalassaemia-2. The patient also had an additional alpha-thalassaemia-1 deletion, an approximately 20.5 kb deletion, common among Mediterranean populations. The Hb Icaria mutation, i.e. the TAA AAA mutation at codon 142, was identified by hybridization of amplified dna with specific probes. The mutation is located on the alpha 2-globin gene; the one remaining alpha 1-globin gene is apparently able to compensate sufficiently for the loss of the three alpha-globin genes to maintain a haemoglobin level of 8-9 g/dl.- - - - - - - - - - ranking = 1keywords = hybridization (Clic here for more details about this article) |
6/17. The beta zero-thalassemia in an American black family is due to a single nucleotide substitution in the acceptor splice junction of the second intervening sequence.An AG dinucleotide is an invariant feature of all acceptor splice sites, and deletion or substitution of (one of) these nucleotides will result in abnormal processing of the beta-globin mRNA. Restriction endonuclease mapping of dna from an American black patient with Hb S-beta zero-thalassemia failed to detect any deletion in the beta 0-globin gene region, but cloning and sequencing of the beta 0-globin gene showed a point mutation (A C) in the highly conserved dinucleotide AG of the acceptor splice junction of the IVS-2. Blot hybridization analysis of rna prepared from the erythroid cells of the patient showed only rna of normal size. The patient and her daughter, who has the same condition, have high levels of Hb F (27%-35%); the mechanism responsible for the greatly increased gamma chain production remains unclear.- - - - - - - - - - ranking = 1keywords = hybridization (Clic here for more details about this article) |
7/17. Homozygous beta-thalassemia without anemia.A 37-year-old man of Guyanese origin was found to have homozygous beta-thalassemia without anemia. There were no physical stigmata of thalassemia. The hematocrit value was 41 to 45.8, the mean corpuscular volume was 61 fL, and the mean corpuscular hemoglobin was 18.9 pg. The HbF was 45% with a G gamma:A gamma ratio of 3:1. An acid elution preparation of the peripheral blood showed heterogeneous distribution of HbF, but all erythrocytes stained for fetal hemoglobin. The beta/alpha synthesis ratio in the peripheral blood was 0.25; the (beta gamma)/alpha ratio was 0.55. Haplotype analysis revealed homozygosity for the - - pattern (senegal, type IX) at seven polymorphic restriction sites within the beta-like gene complex. digestion of dna with Xmnl indicated that the -158 C-to-T transition was present in both beta-globin gene clusters. Oligomer hybridization analysis demonstrated homozygosity for the -29 A-to-G mutation in the beta-globin promoter region. Although this form of thalassemia can cause transfusion-requiring anemia, the high-HbF, high-G gamma phenotype associated with the linked - subhaplotype and -158 C-to-T substitution appears to have ameliorated the disease in this subject.- - - - - - - - - - ranking = 1keywords = hybridization (Clic here for more details about this article) |
8/17. Nucleotide variations in the 3' A gamma enhancer region are linked to beta-gene cluster haplotypes and are unrelated to fetal hemoglobin expression.Molecular cloning and sequence analysis of a nondeletion form of Sicilian beta o hereditary persistence of fetal hemoglobinemia (HPFH) (mutation in IVS2 nt1 position) homozygous for haplotype III revealed the presence of four sequence variations: C T at -158 5' to G gamma, T C at 2285, C A at 2476, and A G at 2676, all 3' to A gamma. The latter three variations in the putative A gamma enhancer are identical to those observed in the case of Seattle HPFH. However, a severe beta o-thalassemia case from algeria (mutation in IVS1 nt1 position), also homozygous for haplotype III, revealed the same nucleotide variation, albeit an inefficient HbF production. We conclude that the variations in the A gamma enhancer element do not play a role in the regulation of HbF production. To assess both the linkage of these sites with the beta-cluster haplotype and the extent of the polymorphism, we examined several black and Mediterranean chromosomes, by PCR amplification followed by both EspI digestion and oligonucleotide hybridization. Our data indicate that these sequence variations in the enhancer element are absent in Mediterranean haplotypes I, V, and VII but are consistently associated with Mediterranean haplotypes II, III, and IX, as well as with the black beta c-associated haplotype. The common feature of all the latter haplotypes is the presence of a polymorphic PvuII site between A gamma and psi beta, which is thus in linkage disequilibrium with the variations in the A gamma enhancer.(ABSTRACT TRUNCATED AT 250 WORDS)- - - - - - - - - - ranking = 1keywords = hybridization (Clic here for more details about this article) |
9/17. Frameshift codon 5 [Fsc-5 (-CT)] thalassemia; a novel mutation detected in a Greek patient.sequence analysis and dot-blot hybridization of dna from a Greek patient with a transfusion dependent thalassemia revealed the combination of a beta IVS-I-1 G A mutation (beta(0) -thalassemia) and a hitherto undescribed frameshift mutation; the latter concerns the absence of a CT dinucleotide from codon 5 and results in a termination signal at the new codon 21 (also a beta (0)-thalassemia).- - - - - - - - - - ranking = 1keywords = hybridization (Clic here for more details about this article) |
10/17. Authentic beta-globin mRNA sequences in homozygous betaO-thalassemia.In a patient with homozygous betaO-thalassemia in whom studies of reticulocyte hemoglobin synthesis showed no beta-globin chain synthesis in vivo and in vitro, molecular hybridization studies revealed rna sequences complementary to beta-globin cDNA. The fact that these sequences were authentic beta-globin mRNA was shown by fingerprint analysis of T1 ribonuclease-digested mRNA and by sequencing of oligonucleotides unique to beta-globin mRNA. The beta-mRNA that failed to direct beta-globin chain synthesis was not detectably shortened or degraded and contained poly(A) sequences.- - - - - - - - - - ranking = 1keywords = hybridization (Clic here for more details about this article) |
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