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Methylene blue continues to be used in the gravid female. We report three premature neonates exposed to methylene blue that experienced severe hemolytic reactions requiring exchange transfusions. Two neonates were subsequently diagnosed with G6PD deficiency. Continued caution is warranted prior to the use of methylene blue in the gravid female.
Bone marrow aplasia due to parvovirus B19 infections is usually mild and self-limited. In patients with hereditary or acquired hemolytic anemias, B19 infection can cause a severe and life-threatening anemia due to the shortened half-life of red cells, but here, too, the transient nature of the infection soon remits the symptoms. Chronic infections with parvovirus are more characteristically associated with immunodeficiency states. We report here a case of B19-induced anemia in a patient with G6PD deficiency and hypogammaglobulinemia which was mislabeled as Diamond-Blackfan anemia until the use of modern laboratory techniques allowed a correct diagnosis to be made.
Glucose-6-phosphate-dehydrogenase deficiency is the most common disease-producing enzyme deficiency in man. This paper describes a new glucose-6-phosphate-dehydrogenase variant discovered during the evaluation of an episode of acute hemolytic anemia in a 62-year-old black male, which was temporally related to the ingestion of Tolbutamide. The hemolysis resolved within 10 days despite continuation of Tolbutamide. The erythrocyte glucose-6-phosphate-dehydrogenase activity was significantly decreased, and its electrophoretic mobility was indistinguishable from wild type enzyme, though faster on starch gel with tris, borate, and phosphate buffers. The enzyme had a biphasic pH optimum reduced Km for G-6-P and NADP, decreased utilization of deamino-NADP, and reduced Ki for NADPH. Because the kinetic properties of this enzyme were unique, we have designated it as G6PD Central City.
Actin-binding protein-280 (ABP-280) is a dimeric actin filament crosslinking protein that promotes orthogonal branching of actin filaments and links actin filaments to membrane glycoproteins. We have mapped the ABP-280 filamin gene (FLN) to Xq28 by Southern blot analysis of somatic cell hybrid lines, by fluorescence in situ hybridization, and through identification of portions of the FLN gene within cosmids and YACs mapped to Xq28. The FLN gene is found within a 200-kb region centromeric to the G6PD locus and telomeric to DSX52 and the color vision locus.
A yeast artificial chromosome (YAC) contig of approximately 2.3 Mb has been constructed for the region of the mouse X chromosome between Gabra3 and G6pd. YACs were isolated from four genomic libraries by PCR or hybridization screening for the loci Gabra3, DXHX1104, F8a, DXHX52, DXBay2, L1cam, and Rsvp. Orientation of YACs was performed by isolation of ends using several PCR-based methods, including an adaptation for mouse YAC analysis of interspersed repetitive sequence (IRS)-vector PCR. YAC ends were mapped on a panel of somatic cell hybrids, in an interspecific backcross, using pulsed-field gel (PFG) electrophoresis or by hybridization to other YACs in the contig. Overlapping YACs were further aligned by restriction mapping using rare-cutter restriction endonucleases, as well as by comparison of IRS-PCR fingerprints. This contig represents the largest one assembled to date in the mouse. It should facilitate the isolation of genes in the region and may aid in the completion of a physical contig for the homologous human region, Xq28.
A fibroblast cDNA library was screened by hybridization to a yeast artificial chromosome containing genomic sequences from human Xq28. The majority of positive cDNA clones were found to correspond to the cDNA coding for TXREB, an HTLV-1 enhancer-binding protein. Sequence analysis of the Xq28 genomic DNA revealed a number of deleterious changes compared to the previously reported cDNA. In addition, both the genomic DNA and cDNA isolates were found to be lacking a 599-bp sequence, bracketed by GT and AG, in the 5' untranslated region. These results suggest that the Xq28-linked gene is a processed pseudogene for TXREB and that the previously reported cDNA was only partially processed. Southern blot analysis on a hybrid mapping panel confirmed the presence of at least one autosomal gene for TXREB, and Northern blot hybridization with the 599-bp putative intron probe confirmed that the sequence is not part of the mature mRNA. Further analysis showed that the gene is expressed in a variety of human tissues and that the pseudogene is located between the genes for the proteins p55 and G6PD.
The transcriptional organization of the region of the mouse X chromosome between the G6pd and the Fln1 genes was studied in detail, and it was compared with the syntenic region of the human chromosome. A cosmid contig of 250 kb was constructed by screening mouse cosmid libraries with probes for human genes and with whole cosmids. Overlapping cosmids were aligned by comparing EcoRI and rare-cutter restriction enzyme digestions. The gene order and the orientation of transcription were determined by hybridization with fragments from the 5' and 3' moieties of each cDNA. Our work demonstrates that all of the new genes identified in human are present in the mouse. The size of the region, 250 kb, is also very similar, as are gene order and gene organization: the transcriptional organization in "domains" described in human is found to be identical in the mouse. The major difference detected is the much lower content in rare-cutter restriction sites, which is related to the lower G+C and CpG content of mouse DNA. The very high conservation that we have described suggests that a potent selective pressure has contributed to such conservation of gene organization.
In order to test hypotheses about the phylogenetic relationships among living genera of New World monkeys, 1.3 kb of DNA sequence information was collected for two introns of the glucose-6-phosphate dehydrogenase (G6PD) locus, encoded on the X chromosome, for 24 species of New World monkeys. These data were analyzed using a maximum parsimony algorithm. The strict consensus of the three most-parsimonious gene trees that result shows support for the following clades: a pitheciine clade including Callicebus within which Chiropotes and Cacajao are sister taxa, an Alouatta-atelin clade within which Brachyteles is the sister taxon of Lagothrix and which is sister to another clade containing the callitrichines, and a callitrichine/Aotus/Cebus/Saimiri clade. Within the callitrichines, Callimico is the sister taxon of Callithrix. Cebus and Saimiri form a clade. These results are broadly consistent with previously published DNA sequence analyses of platyrrhine phylogeny and provide additional support for groupings provisionally proposed in those earlier studies. Nevertheless, questions remain as to the relative phylogenetic placement of Leontopithecus and Saguinus, the branching order within the Aotus/Cebus/Saimiri/callitrichine clade, and the placement of the pitheciine clade relative to the atelines and the callitrichines.
The entire coding sequence of a Japanese class 1 variant (G6PD Tokyo) was amplified by the polymerase chain reaction from genomic DNA. Nucleotide analysis by a direct sequencing technique revealed a unique nucleotide substitution (1246 G to A) in exon 10, which predicts a Glu to Lys substitution at the 416th amino acid. This is another member of a conspicuous mutation cluster surrounding the putative NADP-binding domain.
Ten variants of erythrocyte glucose-6-phosphate dehydrogenase were identified in 22 patients with G6PD deficiency from three districts of Bulgaria. Corinth-like and Fayoum-like variants were the most frequent; Mediterranean, Ohut II, Kilgore, Boston, Poznan, and Panay variants and two new variants, Petrich and Gotze Delchev, were each found in one or two carriers. No correlation was revealed between clinical and biochemical polymorphism.
A new G6PD variant has been detected in a Cuban male and there is no evidence of associated hematological abnormalities. The main characteristics of this variant, moderate deficiency, slow electrophoretic mobility, increased utilization of the substrate analogues, and a different chromatographic behavior, indicate that it is a variant that has not been previously described.
The syndrome of torticollis, keloids, cryptorchidism and renal dysplasia was described by Goeminne (1968) in a large family, and listed as X-linked incomplete dominant by McKusick (1978; No. 31430). We mapped the locus on the long arm of the X chromosome at band q28 and distal to the G6PD locus. This was achieved by the chance discovery in the literature that two females, each with a balanced X/autosome translocation involving Xq28, had partial manifestation of the syndrome as was the case with the females in the larger family of Goeminne (1968).
We selected the common shrew (Sorex araneus) to generate the first insectivore gene map. Shrew-Chinese hamster and shrew- mouse somatic cell hybrid cells were constructed. When the 119 shrew-rodent clones were characterized, only shrew chromosomes were found to have segregated. A panel of hybrid clones was selected for gene assignment. The genes for hypoxanthine phosphoribosyl transferase (HPRT), glucose-6- phosphate dehydrogenase (G6PD), and malate dehydrogenase 1 (MDH1) were assigned to shrew Chromosome (Chr) de [which is the product of a tandem fusion between the 'original' mammalian X Chromosome (Chr) and an autosome], the gene for adenosine deaminase (ADA) and 6-phosphogluconate dehydrogenase se (PGD) to Chromosome jl, the gene for thymidine kinase (TK) to Chromosome hn, and the gene for lactate dehydrogenase (LDHA) to chromosome ik. Further studies in progress.
G6PD isozyme variation in Drosophila melanogaster is investigated in the larval stage through electrophoretic and genetic analyses. As current structural models for this gene-enzyme system fail to apply in these laboratory populations, the authors suggest a regulatory hypothesis to explain their observations.
A 2850-base-pair-long DNA segment containing the transcriptional start site of the human X-linked gene coding for the housekeeping enzyme glucose-6-phosphate dehydrogenase has been fused to the reporter chloramphenicol acetyl transferase gene. This fusion was introduced into three different mammalian cell lines (HepG2, CVI and HeLa). Strong expression was detected and transcription initiated at the natural start site. By deletion analysis, we determined that a 436 base pair region of this promoter is sufficient for full expression of the chimaeric construct and therefore the remainder of the CpC island surrounding the transcriptional start site and differentially methylated in the active and inactive X chromosome is not necessary for transcriptional activity in this assay. Further sequence deletions from -436 to -116 base pairs decrease the promoter-directed chloramphenicol acetyl transferase activity. Site-directed mutagenesis of a TATA-like sequence present in the G6PD promoter shows that this site is required for a correct start of transcription but not for determining the level of gene expression.
The human S11 surface antigens are expressed on fibroblasts and are coded by a gene on the X-chromosome. We have regionally mapped this gene by examining S11 expression on a panel of hybrid lines which had fragmented the X-chromosome either during chromosome-mediated gene transfer, or by interspecies translocation during hybrid cell expansion. using indirect immunofluorescence and the fluorescence-activated cell sorter (FACS), it was possible to isolate antigen-positive and -negative hybrid subpopulations for subsequent genetic analysis. The gene coding S11 could be localized to Xq27-28, between the loci for HPRT and G6PD where genes for the S10 and S12 antigens have been previously mapped. This work demonstrates the value of cell surface antigens and the FACS in somatic cell genetic analysis, and provides evidence for regional clustering of surface antigen loci on the human X-chromosome.
Studies of a unique clone of skin fibroblasts from a normal 46 XX female reveal that the G6PD locus on the inactive X chromosome has been derepressed. The reactivation event occurs spontaneously, and is associated with normal karyotype, including the presence of a late-replicating X chromosome. Analysis of mouse-human hybrids with the relevant chromosome provides evidence that the derepressed locus is on the inactive X, and that reactivation is not extensive (the PGK locus is not derepressed). Nor is any general change in DNA methylation of this chromosome detectable with Hpa II and an X-specific DNA probe. Studies of the glucose-6-phosphate dehydrogenase phenotype in these heterozygous cells indicate that the reactivated X produces only half the enzyme subunits as are produced by the active X. Although this dosage difference may be related to the mutational event responsible for derepression of the locus, these observations along with other evidence suggest that loci on the inactive X, when expressed, have less activity than corresponding loci on the active X.
An improved method of microdetermination of G6PD isoenzyme activity in human erythrocytes was developed by modification of previously reported procedures. The volume of blood samples was reduced from 2 ml to 20 microliters. After hemolysis in 2% Triton X-100 and 0.1% beta-mercaptoethanol, the samples were subjected to centrifugation and thin-layer isoelectric focusing in polyacrylamide gel (PAG-IEF). By comparison with the original method, excellent resolution was obtained by this more rapid and simple procedure.