Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound   Target Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound

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Query: EC:3.1.30.2 (endonuclease)
18,621 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Hemoglobin A2 levels in normal adults are rarely greater than 3.5%. In patients heterozygous for beta-thalassemia, they average about 5% but do not usually exceed 7%. We studied a family in which four patients with heterozygous beta-thalassemia had HbA2 levels of 8.4% to 11.2%. Globin biosynthesis studies and restriction endonuclease mapping of the alpha-globin loci showed homozygous or heterozygous alpha-thalassemia-2 as well as beta-thalassemia in some family members. The delta- and beta-globin genes were examined by using the restriction enzymes Eco RI, Pvu II, and Xba I, which cut both within and outside the coding portions of the delta- and beta-loci. Only the expected delta- and beta-globin gene containing fragments were present, excluding a crossover event producing a fusion gene that would code for delta-globin but possibly be under the regulatory influence of nucleotide sequences that control the expression of the beta-gene. This kindred provides evidence that in the presence of beta-thalassemia, expression of the delta-gene, beyond that commonly seen, is possible. This could be a direct result of the gene defect producing beta-thalassemia or be due to differences in the delta-globin gene linked to this beta-thalassemia gene. The interactions of alpha- and beta-thalassemia may alter tetramer assembly and increase HbA2 levels; however, this possibility seems less likely.
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PMID:Beta-thalassemia with exceptionally high hemoglobin A2. Differential expression of the delta-globin gene in the presence of beta-thalassemia. 628 19

The restriction endonuclease MstII cleaves the human beta-globin gene at the position corresponding to amino acids 5, 6, and 7. The beta S mutation at this position abolishes the recognition site. Hence, the two normal DNA fragments in this region, 1.15 and 0.2 kb in length, are replaced by a single 1.35-kb fragment in DNA from sickle cell anemia. We have set up an assay using these findings. The assay is extremely sensitive and can be applied to DNA directly harvested from 20 ml of amniotic fluid.
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PMID:A sensitive test for prenatal diagnosis of sickle cell anemia: direct analysis of amniocyte DNA with MstII. 630 79

Restriction endonuclease mapping of cellular DNA with the enzyme Sst I has been used to detect the haemoglobin (Hb) Milwaukee mutation directly. Instead of a normal 15.5 kilobase pairs (kb) fragment which contains the normal beta-globin structural genes, in heterozygous Hb M Milwaukee DNA two additional fragments of 9.0 kb and 6.5 kb were obtained that are diagnostic for this anomaly. The position of Sst I sites within the beta-globin gene region could be established.
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PMID:Analysis of the Hb M Milwaukee mutation at the DNA level. 630 36

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.
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PMID:Delta +-thalassemia in Sardinia. 630 32

We describe a new type of gamma delta beta-thalassemia in four generations of a family of Scotch-Irish descent. The proposita presented with hemolytic disease of the newborn, which was characterized by a microcytic anemia. Initial restriction endonuclease analysis of the DNA showed no grossly abnormal patterns, but studies of polymorphic restriction sites and gene dosage revealed an extensive deletion that removed all the beta- and beta-like globin genes from the affected chromosome. In situ hybridization of chromosome preparations with radioactive beta-globin gene probes showed that only one 11p homolog contained the beta-globin gene cluster in the affected family members.
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PMID:Hemolytic disease of the newborn caused by a new deletion of the entire beta-globin cluster. 630 57

Restriction endonuclease mapping of cellular DNA has been used to identify chromosomes that carry the mutant Hb Presbyterian beta-globin genes in a family with individuals heterozygous for this disease. The presence of the polymorphic Hind III restriction site in the G gamma-globin gene and its absence in the A gamma-globin gene were shown to be in phase with the Hb Presbyterian mutation yielding a haplotype constellation that is diagnostic for any further affected offspring.
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PMID:DNA restriction mapping identifies the chromosome carrying the mutant Hb Presbyterian beta-globin gene. 630 49

We have used the restriction endonuclease mapping technique to analyse the globin genes in local cases of beta-thalassaemia major. No gross deletions or rearrangements of the beta-globin gene locus were detected. In one individual the point mutation within the beta-globin gene which gives rise to a beta(0)-thalassaemia allele was detected by use of a restriction enzyme which cuts the gene at this site. Analysis of restriction fragment length polymorphisms at the beta-globin locus showed that antenatal diagnosis of the disorder could be accomplished in an indigenous family with thalassaemia. The application of the gene-mapping technique to the diagnosis of sickle cell anaemia and alpha-thalassaemia is also discussed.
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PMID:Restriction endonuclease mapping of globin genes in beta-thalassaemia. 631 Aug 4

The continuous DNA sequence of a 16.5-kilobase pair region encompassing the linked delta beta-globin gene cluster in humans is presented with a detailed restriction endonuclease map. There are 38 differences (0.5%) in comparison with published sequence data, corrected for errors in sequencing, resulting in polymorphic rates of 0.2% in exons and 0.76% in 5'-gene flanking regions. Fifteen changes result in the generation or elimination of restriction sites which may be useful in linkage disequilibrium studies. Two pairs of inverted Alu repeats, a pyrimidine-rich region 5' to delta, and (TG)n, (Pu/Py)n, and (ATTTT)n tracts 5' to beta are described. Dinucleotide frequencies and deviation from expected values approximated those found in total human genomic DNA. Regions of less than 50% A + T content were found associated with Alu sequences, a 150-base pair region immediately 5' to the beta gene, exon regions from both genes, and an area 3' to the beta gene. These regions also contained significantly lower than expected CpG levels compared to other regions, suggesting a possible relationship between DNA organizational patterns and functionally important regions. In addition, strand asymmetries in base composition in this region differ from those associated with the fetal globin genes.
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PMID:Nucleotide sequence analysis of the delta beta-globin gene region in humans. 631 16

Digestion of DNA from a patient with homozygous beta zero thalassemia from Calabria, Italy with the restriction endonuclease Mst II produced a pattern similar to the one obtained with sickle cell trait DNA in that the Mst II site at the beta 6 position on one chromosome was abolished. We cloned the DNA from this beta-thalassemia chromosome and performed sequence analysis. The deletion of a single nucleotide (A) at the GAG codon of the beta 6 position results in a frame shift and early beta-globin chain termination. This mutation occurs on a chromosome with a haplotype similar to two other Mediterranean beta-thalassemia lesions. The Mst II enzyme is useful for prenatal diagnosis of beta thalassemia in this population.
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PMID:A beta-thalassemia lesion abolishes the same Mst II site as the sickle mutation. 631 72

beta-Thalassemia, a heterogeneous group of human anemias affecting the expression of beta-globin, is caused by a number of molecular defects. Restriction endonuclease mapping of ethnic populations has revealed many polymorphisms within and around the beta-like globin genes, combinations of which are assigned as haplotypes. Several haplotypes appear to be strongly linked with the molecular defects causing thalassemia in Greek and Italian patients (Orkin et al. 1982). We describe here haplotypes from 40 Algerian beta-thalassemic patients and eight normals determined by restriction endonuclease mapping at seven polymorphic sites. Four haplotypes previously unreported were observed in these thalassemic patients; this argues the existence in this population of undescribed beta-thalassemia alleles. The knowledge of the haplotypes in thalassemic families could be used for prenatal diagnosis of homozygote forms.
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PMID:Four new haplotypes observed in Algerian beta-thalassemia patients. 631 40


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