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At least 271 records · Page 15Linked to original sources
PubMed1997

Tandem duplications of the FLT3 receptor gene are associated with leukemic transformation of myelodysplasia.

We recently reported an internal tandem duplication of the human flt3 receptor gene (FLT3) as a somatic mutation in 17% of acute myelogenous leukemia (AML). The present study revealed the duplication at the juxtamembrane and the first tyrosine kinase domains of FLT3 in seven of 92 (8%) patients with myelodysplastic syndrome (MDS) and AML with trilineage myelodysplasia (AML/TMDS), the diseases which may represent neoplastic changes of pluripotent stem cells. A tandem duplication of exon 11 of FLT3 was harbored by two of 58 (3%) patients with MDS and five of 34 (15%) with overt leukemia, including MDS-derived leukemia, AML/TMDS and therapy-related leukemia. Although the duplicated regions varied within exon 11 in each case, they occurred in-frame, and altered mRNA expressions were demonstrated by reverse-transcription polymerase chain reaction. Two cases of MDS with a FLT3 duplication transformed to overt leukemia within a few months. Longitudinal analyses in two other patients with leukemia revealed that the duplication was a late genetic event during the disease course; one of whom showed two independent duplications of FLT3 at the terminal therapy-resistant phase. Of seven patients with the FLT3 duplication, six had abnormal karyotypes, and four harbored a point mutation of the N-RAS and/or TP53 genes. Patients with FLT3 mutations have poor prognoses. This study uncovered the fact that the accumulation of genetic events, including FLT3 duplication, correlates with leukemic transformation from antecedent myelodysplasia and with subsequent disease progression.

Aged↗
PubMed2002

Incidence and pattern of long saphenous vein duplication and its possible implications for recurrence after varicose vein surgery.

BACKGROUND: The incidence of long saphenous vein (LSV) duplication has not been clearly established. This anomaly could have implications for recurrence after varicose vein surgery. METHODS: Some 103 saphenograms obtained in 85 patients being considered for peripheral arterial bypass surgery were reviewed. Non-ionic contrast medium was injected directly into the vein or its tributaries at the ankle. Duplications of the LSV and their relation to thigh and calf perforator veins were assessed and recorded by two independent observers. RESULTS: There was evidence of duplication of the LSV in 50 (49 per cent) of the 103 saphenograms. Most duplications were present in the thigh (88 per cent) and the most common pattern was a closed loop (54 per cent). Perforator veins were connected to one branch of the duplication in 42 per cent of the legs (20 per cent of all 103 legs); in half the perforator vein was connected to the non-dominant branch of the duplication. Only ten of the 18 patients who had bilateral saphenograms had duplications in both legs, and only one patient had the same pattern of duplication on both sides. CONCLUSION: The incidence of LSV duplications is higher than previously reported.

Adult↗
PubMedDate not supplied

The "Bilhaut-Cloquet" technique for treatment of thumb duplication.

The presentation of thumb duplication is variable depending on the level of bifurcation, the relative sizes of the two thumbs and their possible symmetry along a longitudinal axis. Resection of the supernumerary thumb often leads to disappointing results when both thumbs are hypoplastic. The principle of the "Bilhaut-Cloquet" procedure involves central resection of the duplication followed by fusion of the remaining lateral portions, in order to obtain a thumb of satisfactory volume. Thirteen children with unilateral thumb duplication were treated using the "Bilhaut-Cloquet" procedure. Nine cases involved duplication of the distal phalanx (Wassel type II). Five of these duplications were symmetrical and four were asymmetrical with an associated proximal delta phalanx. In these cases, a corrective osteotomy of the delta phalanx was performed at the same time. Four cases involved symmetrical duplications of both proximal and distal phalanges (Wassel type IV). The mean age at time of surgery was 11.5 months. Patients were reviewed with a mean follow-up of four years. The aesthetic aspect of the nail was judged as good in 12 cases. In one case, the aesthetic aspect of the nail was judged as fair due to a prominent longitudinal ridge. Bony fusion was obtained in all cases but one. The alignment was corrected in all cases but four, involving asymmetrical duplications. Joint mobility was limited in all patients. The "Bilhaut-Cloquet" technique leads to a satisfactory volume of the thumb in selected cases. Good correction of preoperative angular deformity is obtained in symmetrical cases. A precise technique of bone and nail approximation yields good functional and aesthetic results. The "Bilhaut-Cloquet" technique is indicated in balanced and symmetrical duplications, when the two thumbs are severely hypoplastic. It can be used either in the distal or proximal phalangeal types of thumb duplication.

Child↗
PubMed2005

Segmental duplications and copy-number variation in the human genome.

The human genome contains numerous blocks of highly homologous duplicated sequence. This higher-order architecture provides a substrate for recombination and recurrent chromosomal rearrangement associated with genomic disease. However, an assessment of the role of segmental duplications in normal variation has not yet been made. On the basis of the duplication architecture of the human genome, we defined a set of 130 potential rearrangement hotspots and constructed a targeted bacterial artificial chromosome (BAC) microarray (with 2,194 BACs) to assess copy-number variation in these regions by array comparative genomic hybridization. Using our segmental duplication BAC microarray, we screened a panel of 47 normal individuals, who represented populations from four continents, and we identified 119 regions of copy-number polymorphism (CNP), 73 of which were previously unreported. We observed an equal frequency of duplications and deletions, as well as a 4-fold enrichment of CNPs within hotspot regions, compared with control BACs (P < .000001), which suggests that segmental duplications are a major catalyst of large-scale variation in the human genome. Importantly, segmental duplications themselves were also significantly enriched >4-fold within regions of CNP. Almost without exception, CNPs were not confined to a single population, suggesting that these either are recurrent events, having occurred independently in multiple founders, or were present in early human populations. Our study demonstrates that segmental duplications define hotspots of chromosomal rearrangement, likely acting as mediators of normal variation as well as genomic disease, and it suggests that the consideration of genomic architecture can significantly improve the ascertainment of large-scale rearrangements. Our specialized segmental duplication BAC microarray and associated database of structural polymorphisms will provide an important resource for the future characterization of human genomic disorders.

Chromosomes, Artificial, Bacterial↗
PubMed1989

Role of gene duplications in the adaptation of Salmonella typhimurium to growth on limiting carbon sources.

Duplication-containing cells are selected when growth of Salmonella typhimurium is limited by the availability of any one of several carbon and energy sources. Under conditions of extreme starvation, growth occurs almost exclusively in the duplication-containing fraction of the population. Cells with duplications of one large segment of the chromosome are repeatedly selected regardless of which of these carbon sources limits growth. The duplicated chromosomal segment encodes the transport systems for all of these carbon sources. This duplication is not selected during growth on a carbon source for which the permease is not included within the duplication segment. This suggests that the growth advantage conferred by the duplication may be due to increased transport of the limiting carbon source. Inclusion of the permease alone is not sufficient to explain the growth advantage of the duplications, since other common duplications that include the permease are not selected.

Adaptation, Physiological↗
PubMed1997

Characteristics and distribution of large tandem duplications in brook stickleback (Culaea inconstans) mitochondrial DNA.

Most animal mitochondrial DNAs (mtDNAs) range in size from 15 to 18 kb, but increased sizes up to approximately 40 kb are occasionally found. We investigated large size variation in mtDNA of the brook stickleback fish, Culaea inconstans, and characterized four large (2.7-5.8 kb) tandem duplications. Duplications differ in size, frequency of occurrence, and degree of associated heteroplasmy, but each includes the control region and one or more adjacent genes. Duplications are correlated with two mtDNA lineages sampled from 31 populations. L1 duplications (3.2-4.8 kb) were present in all lineage I individuals (n = 121, 19 populations); 53 fish were heteroplasmic due to variation in the copy number of a tandemly repeated 270-bp sequence within the duplicated region. In contrast, duplications, L2, L3, and L4 (2.7-5.8 kb) occurred in only 117 of 174 lineage II fish, in eight of 14 populations. Nine fish with L3 or L4 duplications were heteroplasmic, possessing some mtDNAs that lacked duplications (normal-length mtDNAs). Heteroplasmy in L2 was associated with a small variable region near the ND5 gene. Phylogenetic analysis of restriction sites in Culaea mtDNAs and haplotype-defining sequence differences present in both copies argue for multiple independent events that gave rise to three of the four duplications.

Animals↗
PubMed1997

Occurrence of repeat induced point mutation in long segmental duplications of Neurospora.

Previous studies of repeat induced point mutation (RIP) have typically involved gene-size duplications resulting from insertion of transforming DNA at ectopic chromosomal positions. To ascertain whether genes in larger duplications are subject to RIP, progeny were examined from crosses heterozygous for long segmental duplications obtained using insertional or quasiterminal translocations. Of 17 distinct mutations from crossing 11 different duplications, 13 mapped within the segment that was duplicated in the parent, one was closely linked, and three were unlinked. Half of the mutations in duplicated segments were at previously unknown loci. The mutations were recessive and were expressed both in haploid and in duplication progeny from Duplication x Normal, suggesting that both copies of the wild-type gene had undergone RIP. Seven transition mutations characteristic of RIP were found in 395 base pairs (bp) examined in one ro-11 allele from these crosses and three were found in approximately 750 bp of another. A single chain-terminating C to T mutation was found in 800 bp of arg-6. RIP is thus responsible. These results are consistent with the idea that the impaired fertility that is characteristic of segmental duplications is due to inactivation by RIP of genes needed for progression through the sexual cycle.

Crosses, Genetic↗
PubMed1975

Selection for a large genetic duplication in Salmonella typhimurium.

Salmonella typhimurium strains containing a duplication of nearly a third of the genome have been isolated by a simple procedure involving selection for improved utilization of L-malate as sole carbon source. The duplication occurs at a very high spontaneous frequency. Strains containing the duplication can be isolated selectively on malate medium, or by a non-selective procedure involving Hfr conjugation. When strains containing the duplication are maintained on non-selective medium, the duplication is readily lost. Genetic evidence suggests that the duplication is chromosomal and tandem. The fact that the recA gene is included in the duplication has been used to obtain evidence that the recA1 marker is recessive to its wild-type allele. Unlike tandem duplications previously described in I. coli, the duplication described in this report appears to have unique endpoints.

Acetates↗
PubMed1998

Phylogenetic tests of the hypothesis of block duplication of homologous genes on human chromosomes 6, 9, and 1.

There are 10 gene families that have members on both human chromosome 6 (6p21.3, the location of the human major histocompatibility complex [MHC]) and human chromosome 9 (mostly 9q33-34). Six of these families also have members on mouse chromosome 17 (the mouse MHC chromosome) and mouse chromosome 2. In addition, four of these families have members on human chromosome 1 (1q21-25 and 1p13), and two of these have members on mouse chromosome 1. One hypothesis to explain these patterns is that members of the 10 gene families of human chromosomes 6 and 9 were duplicated simultaneously as a result of polyploidization or duplication of a chromosome segment ("block duplication"). A subsequent block duplication has been proposed to account for the presence of representatives of four of these families on human chromosome 1. Phylogenetic analyses of the 9 gene families for which data were available decisively rejected the hypothesis of block duplication as an overall explanation of these patterns. Three to five of the genes on human chromosomes 6 and 9 probably duplicated simultaneously early in vertebrate history, prior to the divergence of jawed and jawless vertebrates, and shortly after that, all four of the genes on chromosomes 1 and 9 probably duplicated as a block. However, the other genes duplicated at different times scattered over at least 1.6 billion years. Since the occurrence of these clusters of related genes cannot be explained by block duplication, one alternative explanation is that they cluster together because of shared functional characteristics relating to expression patterns.

Animals↗
PubMed1998

The exstrophy-epispadias complex in the duplicated lower urinary tract.

PURPOSE: The exstrophy-epispadias complex in combination with a duplicated lower urinary tract is an extremely rare congenital malformation. We describe 2 cases of bladder exstrophy in association with a duplicated lower urinary tract. MATERIALS AND METHODS: We analyzed the case histories of 2 patients. The first case had anteroposterior duplication of the bladder communicating through an isthmus and a duplicate urethra. The anterior system was exstrophic and epispadiac. The second case had a duplicate bladder without epispadias. There was a communication between the anterior exstrophic and posterior normal bladders. No other malformations were present. RESULTS: Both patients underwent excision of the duplicate exstrophic bladder in conjunction with primary closure of the abdominal wall. Postoperative continence was normal. Histological examination confirmed the diagnosed bladder duplication. CONCLUSIONS: Although duplication of the lower urinary tract in combination with the exstrophy-epispadias complex is extremely rare, all children presenting with an exstrophic bladder and a normal urethra alone or in association with an epispadiac anterior urethra should be evaluated for a bladder duplication with possible isthmic communication.

Abnormalities, Multiple↗
PubMed2003

Laparoscopic resection of gastric duplication: successful treatment of a rare entity.

Alimentary tract duplications are rare congenital malformations that may be found anywhere from mouth to anus. They usually share a common smooth muscle wall and blood supply with the adjacent bowel. Some duplications are asymptomatic but most cause problems in early childhood. Gastric duplications account for 2% to 7% of all gastrointestinal duplications. The management of gastric duplication is essentially surgical. The treatment of choice is the complete excision of the gastric duplication without violation of the gastric lumen whenever possible. The authors report an unusual case of gastroesophageal junction duplication completely removed by laparoscopy. To our knowledge, this is the first case of gastric duplication successfully treated by laparoscopy in English literature. Laparoscopic resection may be added to the surgical armamentarium in the treatment of alimentary tract duplications.

Esophageal Cyst↗
PubMed1990

Gene duplication and concerted evolution of the GPDH locus in natural populations of Drosophila melanogaster.

The sn-glycerol-3-phosphate dehydrogenase (GPDH, EC 1, 1, 1, 8) locus of Drosophila melanogaster is polymorphic with respect to the number of tandemly duplicated genes in natural populations. The duplicated genes were cloned and the nucleotide sequences were determined. The duplication deletes both the first and second exons and has a size of 4500 b.p. The fact that there is no sequence variation at the junction point of the duplicated units among strains suggests a single origin for the duplication event. Comparison of the nucleotide sequences among the duplicates indicates that the frequent transfer of genetic information occurs from one to the other of the duplicates on the same chromosome either by gene conversion or by unequal crossing over. Because the GPDH duplication is partial and therefore a kind of pseudogene, the observed polymorphism of the number of tandemly duplicated GPDH genes appears to have been driven mainly by random genetic drift.

Animals↗
PubMed1978

Genetic and segregation analysis of Escherichia coli strains containing a tandem duplication of the trpD-purB region of the chromosome.

Genetic and segregation analysis of Escherichia coli strains containing a partial duplication of the trp operon reveal that the 2.5-min-long region trpD-purB is duplicated in tandem in the chromosome. The adjacent loci cysB and fabD are not duplicated. Although one copy of the duplicated region is longer than the maximum size of bacteriophage P1kc transducing fragments, the frequency at which the duplicated segment trpDCBA is transferred by transduction to tonB-trp deletion strains is equal to that observed for transfer of the normal trp operon. This suggests that three-point recombination events believed to account for transduction of long duplications occur as frequently as two-point recombination events believed to account for normal transduction. Cotransduction frequencies of trpDCBA with the duplicated loci tonB, galU, tyrT, and hemA are very similar to those for the trp operon with the same loci. This indicates that normal genetic linkage is maintained during the three-point recombination event. However, purB, which is normally unlinked to trp by transduction, is closely linked to trpDCBA and thus must be near the repeat point of the duplication. Transduction tests with point mutations in the trp operon indicated that the repeat point occurs near the normal boundary between trpE and trpD. Segregation analysis of heterogenotes constructed from tonB-trp deletion strains shows that the frequency at which a marker is lost is approximately proportional to its distance from the repeat point. This finding is consistent with a random, singlesite crossover event during segregation. Several observations indicate that non-reciprocal genetic exchange also occurs between copies of the duplication. Analysis of heterogenotes containing dadR1 and dadR(+) demonstrate that the mutant allele is transdominant.

Chromosome Aberrations↗
PubMed1992

Duplication within chromosome 17p11.2 in 12 families of French ancestry with Charcot-Marie-Tooth disease type 1a. The French CMT Research Group.

Hereditary motor and sensory neuropathy type I (HMSN I), also designated Charcot-Marie-Tooth disease type 1 (CMT1), is a peripheral neuropathy frequently inherited as an autosomal dominant trait, characterised by progressive distal muscular atrophy and sensory loss with markedly decreased nerve conduction velocity. A duplication within chromosome 17p11.2, cosegregating with the disease, has recently been reported in several CMT1a families. In order to estimate the frequency of this anomaly and determine the location of a duplication in this region, 12 CMT1 families were analysed with polymorphic DNA markers located within 17p11.2-12. Duplications were found in all families including loci D17S61 (EW401), D17S122 (VAW409R3a and RM11-GT), and D17S125 (VAW412R3). The duplications were completely linked and associated with the disease (lod score of 20.77 at zero recombination). Screening for the RM11-GT microsatellite showed that most of the duplicated haplotypes were heterozygous, supporting the hypothesis that the duplication resulted from an unequal crossing over. There was no significant haplotype association within the duplicated region suggesting that the duplication resulted de novo as an independent event in each family. In one family, recombination within the duplicated region was observed, indicating that genetic instability in 17p11.2 might be related to a high recombination rate. Since most cases of CMT1a seem to result from this segmental trisomy, it can be used as a basis for DNA diagnosis of the disease.

Base Sequence↗
PubMed2002

[Urethral sagittal duplication in children. Report of 7 cases].

UNLABELLED: Urethral duplication is a rare disease with various clinical expressions and treatments. The authors report 7 cases. MATERIAL AND METHODS: The authors retrospectively review 7 children with sagittal duplication of the urethra seen between 1995 and 2000. All children were investigated by ultrasonography of the urinary tract, retrograde cystography and voiding cystourethrography. RESULT: Except for one case of neonatal discovery, the mean age at diagnosis in the other six children was 4 years. In one case, the malformation consisted of blind incomplete urethral duplication (type I B) and urethroscopy confirmed the presence of an orifice distal to the urethral cap; symptomatic treatment was successful in this patient. Two children with complete urethral duplication with epispadias and two bladder orifices (type II A1) were successfully treated by resection of the supernumerary urethra. One child presented an U-shaped duplication (type II A2 "Y"). Unsuccessful opacification of the accessory urethra prior to its resection induced sclerosis and no flow with a follow-up of 24 months. Penile surgery was performed in two children with incomplete urethral duplication with only one vesical orifice (type II A2) transforming duplex urethra into distal bifid urethra after resection of the accessory urethra and its epispadic meatus. One child had a suspended duplication of the urethra with only one glandular meatus (type II B2) and a single vesical orifice. He was treated by endoscopic section of the urethral membrane separating the two urethras before their fusion in the bulbar urethra. With a mean follow-up of 36 months (range: 6 months to 4 years) no infectious or voiding complications were observed in these 7 children. CONCLUSION: Sagittal duplication of the urethra is a rare disease requiring precise anatomical and functional assessment. The ideal treatment for symptomatic forms is resection of the duplication without impairing sphincter function.

Child↗
PubMed1993

Molecular analyses of unrelated Charcot-Marie-Tooth (CMT) disease patients suggest a high frequency of the CMTIA duplication.

Charcot-Marie-Tooth disease (CMT) is the most common inherited peripheral neuropathy. One form of CMT, CMT type 1A, is characterized by uniformly decreased nerve conduction velocities, usually shows autosomal dominant inheritance, and is associated with a large submicroscopic duplication of the p11.2-p12 region of chromosome 17. A cohort of 75 unrelated patients diagnosed clinically with CMT and evaluated by electrophysiological methods were analyzed molecularly for the presence of the CMT1A DNA duplication. Three methodologies were used to assess the duplication: measurement of dosage differences between RFLP alleles, analysis of polymorphic (GT)n repeats, and detection of a junction fragment by pulsed-field gel electrophoresis. The CMT1A duplication was found in 68% of the 63 unrelated CMT patients with electrophysiological studies consistent with CMT type 1 (CMT1). The CMT1A duplication was detected as a de novo event in two CMT1 families. Twelve CMT patients who did not have decreased nerve conduction velocities consistent with a diagnosis of CMT type 2 (CMT2) were found not to have the CMT1A duplication. The most informative molecular method was the detection of the CMT1A duplication-specific junction fragment. Given the high frequency of the CMT1A duplication in CMT patients and the high frequency of new mutations, we conclude that a molecular test for the CMT1A DNA duplication is very useful in the differential diagnosis of patients with peripheral neuropathies.

Charcot-Marie-Tooth Disease↗
PubMed1997

Autism or atypical autism in maternally but not paternally derived proximal 15q duplication.

Duplications of proximal 15q have been found in individuals with autistic disorder (AD) and varying degrees of mental retardation. Often these abnormalities take the form of a supernumerary inverted duplicated chromosome 15, more properly described as an isodicentric chromosome 15, or idic(15). However, intrachromosomal duplications also have been reported. In a few cases, unaffected mothers, as well as their affected children, carry the same duplications. During the course of the genotyping of trios of affected probands with AD and their parents, at the positional candidate locus D15S122, an intrachromosomal duplication of proximal 15q was detected by microsatellite analysis in a phenotypically normal mother. Microsatellite and methylation analyses of the pedigree in the following report show that, among three children, the two with autism or atypical autism have maternal inheritance of a 15q11-q13 duplication whereas the third child, who is unaffected, did not inherit this duplication. Their mother's 15q11-q13 duplication arose de novo from her father's chromosomes 15. This finding documents, for the first time, the significance of parental origin for duplications of 15q11-q13. In this family, paternal inheritance leads to a normal phenotype, and maternal inheritance leads to autism or atypical autism.

Aneuploidy↗
PubMed2003

Evolutionary dynamics of duplicated genes in plants.

Gene duplication, arising from region-specific duplication or genome-wide polyploidization, is a prominent feature in plant genome evolution. Understanding the mechanisms generating duplicate gene copies and the subsequent dynamics among gene duplicates is vital because these investigations shed light on regional and genome-wide aspects of evolutionary forces shaping intra- and interspecific genome contents, evolutionary relationships, and interactions. This review discusses recent gene duplication analyses in plants, focusing on the molecular and evolutionary dynamics occurring at three different timescales following duplication: (1). initial establishment and persistence of cytotypes, (2). interactions among duplicate gene copies, and (3). longer term differentiation between duplicated genes. These relative time points are presented in terms of their potential adaptive significance and impact on plant evolutionary genomics research.

Adaptation, Biological↗