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PubMed1997

The G4 gene is duplicated in 44% of human immunoglobulin heavy chain constant region haplotypes.

The structure of the human immunoglobulin heavy chain constant region (IGHC), on chromosome 14q32, comprises nine CH genes and two pseudogenes, all originating from multiple duplication events. Continuing evolution of the region is demonstrated by the finding of various types of duplicated and deleted haplotypes, which together add up to 6%. Here we provide molecular and genetic evidence that the G4 gene is duplicated in 44% of IGHC haplotypes in the Italian population. The duplication spans about 20 kb of genomic DNA and probably originated through unequal crossing over. Refined characterisation of the genomic region downstream from the G4 gene improves our knowledge of the evolutionary history of CH genes.

Blotting, Southern↗
PubMed1990

Complete foregut duplication.

Alimentary tract duplications are rare congenital anomalies with the majority identified in the pediatric age group. However, duplications may be seen in the adult population and require operative excision. A 53-year-old man was seen with vague, nonspecific symptoms and was found to have a complete esophageal and gastric duplication with communication to the normal alimentary tract. Appropriate-for-structure epithelium was noted throughout the length of the duplication.

Barium Sulfate↗
PubMed1988

Amyloid beta-protein gene duplication is not common in Alzheimer's disease: analysis by polymorphic restriction fragments.

The amyloid beta-protein(BP) is an important component of amyloid fibrils of both Alzheimer's disease(AD) and adult Down syndrome(DS). It has been hypothesized that sporadic AD may involve the duplication of a subregion of chromosome 21 containing the BP locus. However, an improved method for detection of the BP gene duplication using polymorphic Hind III fragments led us to a conclusion that BP gene duplication is rare, if any, in (Japanese) sporadic AD patients, indicating that the duplication of the BP gene itself is not the common underlying genetic defect in AD.

Adolescent↗
PubMed1984

Retinoic acid-induced pattern duplication in regenerating urodele limbs.

The effects of varying doses of retinoic acid on forelimb regeneration in larval Ambystoma mexicanum amputated through the wrist joint and in adult Notophthalmus viridescens amputated through the basal carpals were compared. In both species, the major effect of retinoic acid was to cause the proximodistal duplication, in the regenerate, of stump segments proximal to the amputation plane. Transverse axial duplications (anteroposterior and dorsoventral) occurred in a smaller percentage of cases; these consisted of cartilage spurs in axolotls, and extra digits in newts. The frequency and magnitude of the proximodistal and (in the newt) transverse duplications were dose dependent, and the regenerating limbs were maximally sensitive to the retinoid during the period of dedifferentiation and accumulation of blastema cells. The effect of retinoic acid is exerted on cells local to the amputation surface, as shown by the fact that retinoic acid caused the proximodistal duplication of stump segments in regenerates derived from amputated distal lower arm segments grafted to the eyesocket .

Ambystoma↗
PubMed1993

Sequence homology between bacteriorhodopsin and G-protein coupled receptors: exon shuffling or evolution by duplication?

Bacteriorhodopsin (BR) is a membrane protein of known structure, widely used for the homology modeling of G-protein-coupled receptors (GPCR). The observation of apparently transposed sequence similarities between some of the helical domains of BR and GPCR has led to the suggestion that exon shuffling may have occurred in the later evolution of GPCR, which would necessitate a different folding pattern for the seven transmembrane helices of GPCR. An alternate hypothesis is that duplication occurred in the evolution of an ancestral gene, such that helices 5-7 originated as duplicates of helices 1-3, leading to intragenic as well as intergenic similarities between helices 1-3 and 5-7 of BR and various GPCR. Analyses of GPCR and BR sequences suggest that such a duplication may have occurred; symmetry within the BR structure is also consistent with homology between these two regions. The hypothesis of evolution by duplication is consistent with the conventional, unshuffled homology model, which is also supported by the obvious conservation of the retinal binding Lys moiety on helix 7 in both BR and the mammalian opsins.

Amino Acid Sequence↗
PubMed1996

Ultrarapid metabolizers of debrisoquine: characterization and PCR-based detection of alleles with duplication of the CYP2D6 gene.

Up to 7% of Caucasians may demonstrate ultrarapid metabolism of debrisoquine due to inheritance of alleles with duplicated functional CYP2D6 genes. Here we describe the genomic organization of the duplicated CYP2D6 genes in the 42 kb XbaI allele. We postulate that this duplication originates from a homologous, unequal cross-over event which involved two 29 kb XbaI wild-type alleles, and had break points within a 2.8 kb direct repeat (CYP-REP) flanking the CYP2D6 gene. Moreover, we have designed two different PCR assays for detection of alleles with duplicated CYP2D6 genes. Both assays correctly identified 29 out of 29 subjects positive for the 42 kb XbaI allele. No false negative or false positive reactions were observed.

Alleles↗
PubMed1989

Gastrointestinal duplications causing relapsing pancreatitis in children.

Two cases of children with relapsing pancreatitis due to intramural gastrointestinal duplications with ductal communication to the pancreas are reported. A gastric duplication with ectopic pancreatic tissue was detected by endoscopic cholangiopancreatography in the gastric antrum of a 6-yr-old girl. A periampullary duodenal duplication was visualized preoperatively by duodenoscopy and computed tomography in a 10-yr-old boy. Resection of the duplication was curative in each case.

Animals↗
PubMed1983

A computer-interfaced photometer and systematic spacing of duplicates to control within-plate enzyme-immunoassay variation.

A Multiskan photometer for reading microtiter plate enzyme immunoassays was linked with a time sharing computer to facilitate control of assay variation and analysis of results. The interface that converted photometer output to RS-232-C format required changes to divide the output into segments short enough for input to the computer. To measure within-plate variation and investigate how the method of allocating sample duplicates to plate wells may affect the estimation of sample variance, uniformity tests were conducted with 47 plates. Coefficients of variation (CV) among wells within-plates ranged from 4.6 to 20.7% and in two-thirds of the plates exceeded 10%. Duplicates allocated to adjacent wells (method 1) gave consistently higher CV for sample means than duplicates allocated to opposite plate quadrants (method 2). In general, the CV by method 2 was about 30% smaller than that by method 1. Analysis of variance confirmed the effectiveness of the quadrant pattern of duplicate allocation as a method of controlling variation that arises from well position effects.

Analysis of Variance↗
PubMedDate not supplied

Carcinogens induce genetic tandem duplications in Salmonella.

Extensive studies have shown that chemical carcinogenesis involves an initiation-promotion pattern. A gene amplification model of carcinogenesis predicts that initiation involves induction of a genetic tandem duplication. We use a system developed by Anderson and Roth to select for tandem duplication of the histidine operon of Salmonella typhimurium by selection for resistance to 3-amino-1,2,4-triazole. Evidence reported here shows that, consistent with prediction, 10 carcinogens are all active in inducing tandem duplications. Two toxic noncarcinogens show little or no activity under the conditions used in inducing tandem duplication but azide, a mutagenic noncarcinogen, did show some activity. 9 types of evidence now support the gene amplification initiation-promotion model of carcinogenesis.

Amitrole↗
PubMed1979

A study of the quality of duplicated radiographs.

The resolution, contrast, and clinical appearance of radiographs and duplicate radiographs made with two types of duplicating film were compared. Duplicating conditions evaluated were type and shape of light, light-film distance, type of exposure surface, and developer temperature. Major observations were as follows: both Kodak and DuPont films produced clinically acceptable duplicates; Kodak film was faster; DuPont film responded better in incandescent photoflood light than Kodak film; clear glass with appropriate light-film distance was the best exposure surface.

Absorptiometry, Photon↗
PubMed1993

Embryogenesis of enterocystomas-enteric duplication cysts of the tongue.

Enteric duplication cysts of the tongue are unusual lesions that may be confused with dermoid cysts, hemangiomas, lingual thyroid remnants, ranulas, and cystic hygromas. Two cases of lingual enteric duplications are reported in a 5-year-old boy and a 4-month-old boy. In the first case the cyst was lined by gastric-type epithelium, and in the second by colonic-type epithelium. Theories of pathogenesis of enteric duplications include development from small epithelial inclusions trapped during fusion of primordial tissues, from incomplete coalescence of lacunas that form between epithelial cells of the solid core of the developing gut, from persistence of epithelial buds within the wall of the bowel, or from nests of trapped entodermal cells. However, each of these theories presents problems with respect to lingual enteric cysts, as possible trapping of epithelium by fusing primordia does not explain the presence of heterotopic mucosa, and the tongue does not develop in the same manner as the hollow viscera. It becomes apparent therefore that enteric duplication cysts are a heterogeneous group of lesions that share some morphologic features, but perhaps not the same pathogenesis.

Child, Preschool↗
PubMed1983

Structure and reversion of an adenovirus type 2 mutant containing a duplication of the left end of the genome at the right end.

A mutant (dp 201) of human adenovirus type 2 has been isolated that has the left 3% (1110 bp) of the genome duplicated at the right terminus. The structure of the mutant genome was studied by restriction endonuclease analysis and by direct DNA sequence analysis. The duplication has resulted in a deletion of 10 bp of the right inverted terminal repeat (ITR) at the junction of right and left end sequences. This internal ITR is not active in initiation or termination of DNA synthesis. Two subclones of dp 201 that bear a deletion between map positions 2.1 and 6.8 encompassing early gene blocks E1a and E1b were also isolated. One of these isolates (dl 201.1) retains the left end duplication and the other isolate (dl 201.2) lacks the left end duplication and is an apparent revertant of dl 201.1. The original mutant dp 201 also reverts to a wild type sequence at a low rate. Since 10 base pairs of the right ITR are deleted in the mutant, reversion must involve a repair mechanism using one of the two complete left end ITRs in the mutant genome. The mechanisms by which this reversion may occur are discussed.

Adenoviruses, Human↗
PubMed1978

Duplication of male urethra.

Male urethral duplication is an unusal anomaly with many variants including complete duplication from the bladder to the glans penis as well as incomplete and abortive forms. Two cases are presented of duplication of the male urethra of the epispadiac incomplete type. A chart has been constructed to facilitate categorization of the various forms of urethral duplication in the male.

Adult↗
PubMed1992

Duplicated urethra: an anomaly best repaired.

Three cases of urethral duplication are described--two complete and one incomplete. The surgical approaches used in 2 of the 3 cases are described, the third not having come to definitive surgery as yet. In the patient with an incomplete urethral duplication the accessory urethra and associated ventral preputial hood were excised. A repair of the complete duplication was devised in which an end-to-side urethrourethrostomy and penile plastic revision were accomplished. The literature is reviewed and a new classification system for urethral duplication is proposed.

Humans↗
PubMed1983

Relationship between multiple copies of a T. brucei variable surface glycoprotein gene whose expression is not controlled by duplication.

Unlike many other T. brucei variable surface glycoprotein (VSG) genes, the IITat 1.3 gene is not duplicated when it is expressed. Analysis of the multiple copies of this gene present in all IITaR 1 trypanosome clones by restriction enzyme mapping and sequencing shows that the expressed copy may have arisen by duplication and transposition to a telomeric site, as is observed for those VSG genes whose expression is linked to duplication. The existence of a mechanism selecting between a number of complete telomeric VSG gene copies for expression is implied by these results. Comparisons of the nontelomeric copies of the IITat 1.3 gene are consistent with involvement of gene duplication and mutational drift in the evolution of new VSG genes.

Animals↗
PubMed1986

Large inverted duplications are associated with gene amplification.

Amplified DNA can be found in arrays of large repeated units, with each repeat unit containing a marker gene and surrounding DNA sequences. Amplified DNA sequences from established cell lines were assessed for the presence of repeat units in the form of inverted duplications. Inverted duplicated DNA was detected by virtue of its concentration-independent resistance to S1 hydrolysis after denaturation and rapid renaturation. Using this assay, inverted duplications were detected in amplified DNA (both DM and HSR configurations) containing the myc gene (16-50 copies/cell) in four human tumor cell lines and in amplified DNA containing the CAD gene (30-200 copies/cell) in three PALA-resistant BHK cell lines. The widespread association of inverted duplications with amplified DNA must bear on the amplification mechanism.

Animals↗
PubMed1987

Duplication of seven exons in LDL receptor gene caused by Alu-Alu recombination in a subject with familial hypercholesterolemia.

A defective LDL receptor gene in a child with familial hypercholesterolemia produces a receptor precursor that is 50,000 daltons larger than normal (apparent Mr 170,000 vs. 120,000). The elongated protein resulted from a 14 kilobase duplication that encompasses exons 2 through 8. The duplication arose from an unequal crossing-over between homologous repetitive elements (Alu sequences) in intron 1 and intron 8. The mutant receptor has 18 contiguous cysteine-rich repeat sequences instead of the normal nine. Seven of these duplicated repeats are derived from the ligand-binding domain, and two repeats are part of the epidermal growth factor precursor homology region. The elongated receptor undergoes normal carbohydrate processing, its apparent molecular weight increases to 210,000, and the receptor reaches the cell surface where it binds reduced amounts of LDL but undergoes efficient internalization and recycling. The current findings support an evolutionary model in which homologous recombination between repetitive elements in introns leads to exon duplication during evolution of proteins.

Base Sequence↗
PubMed1991

DNA duplication associated with Charcot-Marie-Tooth disease type 1A.

Charcot-Marie-tooth disease type 1A (CMT1A) was localized by genetic mapping to a 3 cM interval on human chromosome 17p. DNA markers within this interval revealed a duplication that is completely linked and associated with CMT1A. The duplication was demonstrated in affected individuals by the presence of three alleles at a highly polymorphic locus, by dosage differences at RFLP alleles, and by two-color fluorescence in situ hybridization. Pulsed-field gel electrophoresis of genomic DNA from patients of different ethnic origins showed a novel SacII fragment of 500 kb associated with CMT1A. A severely affected CMT1A offspring from a mating between two affected individuals was demonstrated to have this duplication present on each chromosome 17. We have demonstrated that failure to recognize the molecular duplication can lead to misinterpretation of marker genotypes for affected individuals, identification of false recombinants, and incorrect localization of the disease locus.

Animals↗