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PubMed1991

Rapid site-specific DNA inversion in Escherichia coli mutants lacking the histonelike protein H-NS.

Escherichia coli pilG mutants are thought to have a dramatically higher DNA inversion rate as measured by the site-specific DNA inversion of the type 1 pili pilA promoter. DNA sequence of the pilG gene confirmed its identity to the gene encoding the bacterial histonelike protein H-NS. Unlike other histonelike protein complexes that enhance site-specific DNA recombination, the H-NS protein inhibited this process. This inhibition was indicated by the increased inversion rate of the pilA promoter region effected by two different mutant pilG alleles. One of these alleles, pilG1, conferred a mutant phenotype only at low temperature attributable to a T-to-G transversion in the -35 sequence of the pilG promoter. The other allele, pilG2-tetR, was an insertion mutation in the pilG coding region that conferred the mutant phenotype independent of temperature. We measured an approximately 100-fold-increased pilA promoter inversion rate in the mutant by exploiting the temperature-dependent expression of pilG1 and using a novel rapid-population-sampling method. Contrary to one current view on how the H-NS protein might act to increase DNA inversion rate, we found no evidence to support the hypothesis that DNA supercoiling affected pilA promoter inversion.

Alleles↗

PubMed1984

Paracentric inversions in man.

We have reviewed 50 cases of paracentric inversions. Of these 34 were familial with 62 phenotypically normal carrier relatives. Twenty of the 50 were discovered fortuitously. There were two reports of children with easily recognised unbalanced karyotypes resulting from a paracentric inversion in one of the parents. The vast majority of paracentric inversions are harmless. The risk of abnormal children for paracentric inversion heterozygotes is low but increases with the finding of recurrent abortions or abnormal children or both in other carriers in the family. We emphasise the need for caution in interpreting the results of antenatal diagnosis because of the variety of unexpected unbalanced chromosome types that can result from a paracentric inversion, and the difficulty in recognising, with confidence, minute differences (for the detection of which very high resolution banding is required) between apparently similar parental and fetal inversions.

Abortion, Habitual↗

PubMed1994

Familial pericentric inversion inv(8)(p23q11).

We describe two families in whom a pericentric inversion, inv(8)(p23q11), is segregating. No examples of unbalanced karyotypes were encountered. The families originated from neighbouring parishes in western Finland. In one family a mild form of mental retardation segregated. However, this phenotype did not cosegregate with the inversion karyotype. There was no evidence of a higher than average abortion rate in the inversion carriers. Carrier matings produced 19 children with a balanced inversion and 14 children with a normal karyotype, concordant with a 1:1 segregation ratio. Of 13 karyotyped men at risk, 10 were inversion carriers. However, this difference was not statistically different from the expected 1:1 ratio. In females, the inversion carrier to normal ratio was 10:11.

Abortion, Spontaneous↗

PubMed1995

Inversions in the factor VIII gene: improvement of carrier detection and prenatal diagnosis in Dutch haemophilia A families.

Haemophilia A is an X linked bleeding disorder caused by a heterogeneous spectrum of mutations in the factor VIII gene. It has recently been reported that about 50% of severe haemophilia A cases are the result of an iversion in the factor VIII gene. The inversion results from homologous recombination between the A gene located in intron 22 of the FVIII gene and one of the two distal A genes, thus disrupting the coding sequence of the factor VIII gene. The inversion can be detected by conventional Southern blotting and hybridisation techniques. Here we present an analysis of 177 unrelated Dutch haemophilia A cases for the presence of an inversion. In 57% of the patients with severe disease an inversion was found and also in at least one of the 26 patients with moderately severe disease. The majority of inversions (85%) involved the most distal A gene, while in a minority (15%) the more proximal A gene was involved. We show that direct mutation detection greatly improves the assessment of carrier status and prenatal diagnosis for haemophilia A, especially in families with an isolated patient. The inversion is predominantly of grandpaternal origin.

Blotting, Southern↗

PubMed1996

Breakpoints in alpha, beta, and satellite III DNA sequences of chromosome 9 result in a variety of pericentric inversions.

Human chromosome 9 with a pericentric inversion involving the qh region is considered normal. It has probably evolved through breakage and reunion and is retained through mendelian inheritance without any apparent phenotypic consequences. Fluorescent in situ hybridisation (FISH) technique using alpha, beta, and satellite III DNA probes showed that the breakpoints are variable and can be localised in the alpha or in the satellite III and beta DNA regions or both. Three types of inversions are proposed which appear similar by CBG banding: pericentric inversions with two alphoid, one beta, and one satellite III hybridisation signals were classified as type A. Type B were those with two beta, one alpha, and one satellite III hybridisation signals, while type C was complex, and most likely involved two inversions, since two separate hybridisation signals were detected in each of the alphoid, beta satellite, and satellite III DNA regions. Based on eight cases, type A is likely to be the most frequent, but the frequencies, which at present appear non-random for these different types of inversions in the population, can only be estimated by studying a larger sample size. Inversion heteromorphisms may promote reshuffling of tandem arrays of DNA repeat sequences, thereby giving rise to new heteromorphic domains. Alternatively, the repetitive nature of the sequences lends to the structural variations observed within the inv(9) chromosomes (or any other abnormal chromosome that is the result of recombination between, or breakage within, repetitive DNA).

Chromosome Inversion↗

PubMed2004

Inversion frequencies in Drosophila serrata along an eastern Australian transect.

Clinal patterns over broad geographic regions provide a way of identifying characteristics of species under selection and are increasingly being used in quantitative trait locus mapping of adaptive genetic variation in Drosophila. However, interpretations of clinal patterns can be complicated by inversions that also vary clinally and reduce recombination in some parts of the genome. Drosophila serrata (Malloch) is an Australian endemic species being used to investigate the genetic basis of geographic variation in climatic adaptation and mate recognition. Here we describe inversions in D. serrata populations from the east coast of Australia, covering tropical and temperate regions. Seven autosomal paracentric inversions and 1 apparently complex X chromosome arrangement were identified from these populations. All inverted arrangements were relatively more common in tropical populations; 2 common inversions showed clinal patterns over part of the range of D. serrata. Inversion polymorphism was relatively higher in tropical populations and almost absent in populations near the cooler southern border, in agreement with findings on other Drosophila species. While these patterns will complicate mapping of adaptive variation in D. serrata, they suggest that this species will be useful in investigatingthe dynamics of inversion-trait associations in natural populations.

Animals↗

PubMed2005

Breakpoint analysis of the pericentric inversion between chimpanzee chromosome 10 and the homologous chromosome 12 in humans.

During this study, we analysed the pericentric inversion that distinguishes human chromosome 12 (HSA12) from the homologous chimpanzee chromosome (PTR10). Two large chimpanzee-specific duplications of 86 and 23 kb were observed in the breakpoint regions, which most probably occurred associated with the inversion. The inversion break in PTR10p caused the disruption of the SLCO1B3 gene in exon 11. However, the 86-kb duplication includes the functional SLCO1B3 locus, which is thus retained in the chimpanzee, although inverted to PTR10q. The second duplication spans 23 kb and does not contain expressed sequences. Eleven genes map to a region of about 1 Mb around the breakpoints. Six of these eleven genes are not among the differentially expressed genes as determined previously by comparing the human and chimpanzee transcriptome of fibroblast cell lines, blood leukocytes, liver and brain samples. These findings imply that the inversion did not cause major expression differences of these genes. Comparative FISH analysis with BACs spanning the inversion breakpoints in PTR on metaphase chromosomes of gorilla (GGO) confirmed that the pericentric inversion of the chromosome 12 homologs in GGO and PTR have distinct breakpoints and that humans retain the ancestral arrangement. These findings coincide with the trend observed in hominoid karyotype evolution that humans have a karyotype close to an ancestral one, while African great apes present with more derived chromosome arrangements.

Animals↗

PubMed2005

Discovery of human inversion polymorphisms by comparative analysis of human and chimpanzee DNA sequence assemblies.

With a draft genome-sequence assembly for the chimpanzee available, it is now possible to perform genome-wide analyses to identify, at a submicroscopic level, structural rearrangements that have occurred between chimpanzees and humans. The goal of this study was to investigate chromosomal regions that are inverted between the chimpanzee and human genomes. Using the net alignments for the builds of the human and chimpanzee genome assemblies, we identified a total of 1,576 putative regions of inverted orientation, covering more than 154 mega-bases of DNA. The DNA segments are distributed throughout the genome and range from 23 base pairs to 62 mega-bases in length. For the 66 inversions more than 25 kilobases (kb) in length, 75% were flanked on one or both sides by (often unrelated) segmental duplications. Using PCR and fluorescence in situ hybridization we experimentally validated 23 of 27 (85%) semi-randomly chosen regions; the largest novel inversion confirmed was 4.3 mega-bases at human Chromosome 7p14. Gorilla was used as an out-group to assign ancestral status to the variants. All experimentally validated inversion regions were then assayed against a panel of human samples and three of the 23 (13%) regions were found to be polymorphic in the human genome. These polymorphic inversions include 730 kb (at 7p22), 13 kb (at 7q11), and 1 kb (at 16q24) fragments with a 5%, 30%, and 48% minor allele frequency, respectively. Our results suggest that inversions are an important source of variation in primate genome evolution. The finding of at least three novel inversion polymorphisms in humans indicates this type of structural variation may be a more common feature of our genome than previously realized.

Animals↗

PubMed2005

Patterns of diversity and linkage disequilibrium within the cosmopolitan inversion In(3R)Payne in Drosophila melanogaster are indicative of coadaptation.

The cosmopolitan inversion In(3R)Payne in Drosophila melanogaster decreases in frequency with increasing distance from the equator on three continents, indicating it is subject to strong natural selection. We investigated patterns of genetic variation and linkage disequilibrium (LD) in 24 molecular markers located within and near In(3R)Payne to determine if different parts of the inversion responded to selection the same way. We found reduced variation in the markers we used compared to others distributed throughout the genome, consistent with the inversion having a relatively recent origin (<N(e) generations). LD between markers and In(3R)Payne varied significantly among markers within the inversion, with regions of high association interspersed by regions of low association. Several factors indicate that these patterns were not due to demographic factors such as admixture and bottlenecks associated with colonization, but instead reflected strong epistatic selection. Furthermore, we found that nonadjacent regions with high association to the inversion contained markers with the strongest clinal patterns in allele frequency; in most cases, the level of clinal variation was beyond what could be explained by hitchhiking with In(3R)Payne, indicating that genes within these regions are targets of selection. Our results provide some support for the hypothesis that inversions persist in natural populations because they hold together favorable combinations of alleles that act together to facilitate adaptive shifts.

Adaptation, Biological↗

PubMed2002

Analysis of the population structure of Anopheles funestus (Diptera: Culicidae) from western and coastal Kenya using paracentric chromosomal inversion frequencies.

In total, 324 Anopheles funestus Giles specimens collected from seven houses in western Kenya and seven in coastal Kenya were scored for their paracentric chromosomal inversions with the aim of determining the level of genetic differentiation based on these inversions. Houses in each area were within a 2-km radius. The two areas are approximately 700 km apart. Only inversions 2a, 3a, 3b, and 5a were found to be polymorphic. Levels of polymorphism varied greatly between inversions. There were no significant deviations from Hardy-Weinberg expectations for samples from individual houses at one site or when data for houses in each area were pooled. Overall, the level of differentiation between western and coastal Kenya was significant, suggesting that the two populations are genetically isolated. Results based on inversion 2a alone were, however, not consistent with this conclusion. Founder effects and selection against the 2a inversion are discussed as possible explanations for this discrepancy.

Animals↗

PubMedDate not supplied

[Puerperal uterine inversion with covered uterine rupture].

Uterine inversion is a rare complication of the postpartum period which can occur in various degrees. The three key symptoms for diagnosis are pain, cardiovascular shock and vaginal bleeding combined with corresponding vaginal and uterine signs of an inversion. Early diagnosis is one of the most important factors determining the outcome of disease. The case of an uterine inversion, caused by a covered rupture of the uterine wall after a cesarean section, is given as an example to discuss predisposing factors and etiologic factors as well as therapy of uterine inversion. As uterine inversion is a rare event, it makes sense and seems to be necessary that new data are presented and discussed in the literature from time to time, especially regarding the cases of inversion in combination with uterine rupture after cesarean section.

Adult↗

PubMed2003

Long distance PCR in detection of inversion mutations of F8C gene in hemophilia A patients.

In the present paper, the experience with detection of intron 22 inversion of F8C gene in severe hemophilia A patients using a recently described long-distance PCR (LD-PCR) method was reported. To test the sensitivity and the specifity of the LD-PCR, analysis of 46 DNA samples of patients and their family members, previously tested by Southern hybridization, was performed. In addition, 16 DNA samples of severe hemophilia A patients in which causative mutation was unknown, were included in analysis. Four-primers, P, Q, A&B, which are able to differentiate between the affected males with or without the inversion, and in female carriers, were used in LD-PCR. Two primers, P&Q, are located within the F8C gene flanking int22h1. Two further primers, A&B, flank int22h2 and int22h3, extragene homologs of int22h1. Nine combinations of four primers were used to identify the optimal one. Four-primers (P, Q, A&B), three-primers (P,Q & B;P, A & B; A, B & Q;P, Q & A) and two-primers (A & B; P & Q; A & Q; P & B) PCR amplifications were performed in the hemophilia A patients as well as in obligate carriers DNA samples. Successful amplification required introduction of some modifications of the original protocol. The most reproducible and uniform results were obtained using two-primers PCR, performed in four single reactions. Thus, a total of 46 DNA samples, 22 were hemizygous for inversion, 6 without the inversion, 14 carriers and 4 non-carriers of inversion. Perfect correlation between genotypes determined using Southern hybridization and LD-PCR was achieved. The optimalized two-primers LD-PCR protocol was used for analysis of 16 DNA samples of severe hemophilia A patients with unknown mutation. Ten cases of inversions and six cases without them were detected. Thus in additional 10 severe hemophilic patients DNA diagnosis was completed. The most successful and reproducible results were obtained performing four single LD-PCR reactions with combinations of two-primers A & B; P & Q; A&Q, and P&B in each DNA sample and this approach is recommended for routine using in clinical practice.

Chromosome Inversion↗

PubMed1986

Acquired inversions in human leucocytes.

Peri- and paracentric inversions are observed in human leukocytes at various rates. Four categories are proposed, in relation to the frequency of occurrence, although it may vary with time for a same inversion. Category 1 corresponds to isolated, thus non recurrent inversions. Category 2 (f congruent to .001) corresponds to inv(14)(q12qter) and inv(7)(p14q35) in individuals with presumably normal genetic constitution. Category 3 (f congruent to .01) corresponds to inv(7)(p14q35) in patients affected by ataxia telangiectasia (AT). This inversion, when it is frequent, indicates an abnormal genetic constitution, radiation sensitive and predisposing to cancers. Finally, category 4 (f greater than or equal to .1) corresponds to inversions existing in precancer or in cancer clonal cells: inv(14)(q11.2q32.2) in AT patients affected by a T-cell hemopathy, inv(14)(q12qter) in chronic T-cell lymphocytic leukaemia, and inv(16)(p13q22) in acute myelomonocytic leukaemia with abnormal eosinophils. The prognostic and diagnostic interests of these inversions is discussed.

Ataxia Telangiectasia↗

PubMed1982

[Pericentric inversions of chromosomes 1, 9 and 16 in patients with sex chromosome anomalies].

Studies on C-heterochromatin in chromosomes 1, 9, 16 in 83 patients with the Shereshevsky-Turner syndrome and in 23 patients with the Klinefelter syndrome revealed the highest number of inversions in chromosome 9 and no inversions in chromosome 16. The inversion frequency in chromosomes 1 and 9 did not significantly differ from the control. Complete inversions were found only in the patients with isochromosome Xq, their frequency being increased in this group. A significant rise of complete inversions in chromosome 9 was found in a group of patients with Klinefelter syndrome. A tendency to inversion concentrations in chromosome 9 under human autosome anomalies, reported in the literature, was also detected in patients with sex chromosome anomalies.

Chromosome Inversion↗

PubMed1996

A novel DNA inversion causing severe hemophilia A.

Almost half of all cases of severe hemophilia A are caused by recurrent DNA inversions, which disrupt the factor VIII (FVIII) gene. These inversions generally occur between a region of intron 22 (int22h) and one of two homologous copies of this region, located 300 to 400 kb telomeric to the FVIII gene. They are routinely detected by a Bcl I Southern blot assay in which the sizes of two of the three normal hybridization bands are characteristically altered. However, atypical hybridization patterns have been observed, and this report describes the first detailed analysis of a hemophilia A patient with such a pattern. The abnormal result was found to be caused by a novel FVIII inversion involving an extra copy of int22h from a site only 70 to 200 kb telomeric of the FVIII gene. Polymerase chain reaction (PCR) allowed one of the inversion junctions to be analyzed, showing that the int22h sequence at this inversion junction was truncated. This patient and his novel inversion provide further evidence that int22h is associated with instability in Xq28.

Base Sequence↗

PubMed1996

Molecular diagnosis of hemophilia A in Chinese patients by an analysis of inversions in the factor VIII gene.

Hemophilia A is an X-linked bleeding disorder caused by deleterious mutations in the factor VIII gene. An inversion caused by introchromosomal homologous recombination between the A gene located in intron 22 of the factor VIII gene and one of the two telomeric A genes has been recently described as the common cause of about 50% of cases of severe hemophilia A. The rearrangement can be readily detected by a Southern blotting procedure. We report use of this procedure to detect rearrangements in 106 unrelated Chinese hemophilia A cases. In 49.3% of the patients with severe disease an inversion was found, but no inversion was detected in any of the patients with moderate or mild disease. The majority of inversions (91.4%) involved the most distal A gene; in a minority (8.6%) the more proximal A gene was involved. These results indicate that intron 22 inversion is the most important molecular defect causing Chinese hemophilia A and that analysis for intron 22 inversion may be the first-line test in the molecular diagnosis of severe hemophilia A.

Asian People↗

PubMed1997

Prevalence, male germ-line origin and new patterns of inversions in haemophilia A.

Following the discovery of the FVIII gene inversion by Lakich et al. [1] and Naylor et al. [2], we have investigated this mutation in 108 French and Algerian severe haemophilia A patients. We have found that only 29 severe haemophiliacs (27%) exhibited the rearrangement whereas Lakich et al. [1] and Naylor et al. [2] respectively estimated the inversion frequency at 47% and 42% in severe haemophiliacs. The reason for this discrepancy is not accounted for. In this study, we observed two novel patterns of inversions as yet unreported. We did not find any correlation between the presence of the inversion and a particular RLFP haplotype, or ethnic origin, or the absence of a FVIII inhibitor. Among the cases with the inversion, the proportion of sporadic and transmitted cases was roughly equivalent and we also confirm that the inversion occurs preferentially in the male germ-line.

Algeria↗

PubMed2006

Simplifying minimally invasive transhiatal esophagectomy with the inversion approach: Lessons learned from the first 20 cases.

HYPOTHESIS: The laparoscopic transhiatal esophagectomy can be simplified and performed safely and effectively by using a novel esophageal inversion technique. DESIGN: Case series describing technique, initial experience, and learning curve with laparoscopic inversion esophagectomy. SETTING: Tertiary care university hospital and veteran's hospital. PATIENTS: Twenty consecutive patients with high-grade dysplasia (n = 16) and esophageal adenocarcinoma (n = 4). INTERVENTION: Laparoscopic inversion esophagectomy, a totally laparoscopic approach to transhiatal esophagectomy that incorporates distal to proximal inversion to improve mediastinal exposure and ease of dissection. MAIN OUTCOME MEASURES: Perioperative end points and complications, compared between the first and second groups of 10 patients. RESULTS: There were 19 men and 1 woman. Median operative time was 448 minutes. Median blood loss was 175 cm3. Median intensive care unit stay was 4 days, and median total hospital stay was 9 days. Overall anastomotic leak rate was 20%. Five patients developed an anastomotic stricture, all successfully managed with endoscopic dilation. There were 2 recurrent laryngeal nerve injuries, which resolved. There was no intraoperative or 30-day mortality. Between the first 10 consecutive cases and last 10 procedures, the incidence of anastomotic leak and stricture formation decreased from 30% to 10% and 40% to 10%, respectively. During this period, the number of lymph nodes harvested increased 9-fold, and duration of intensive care unit stay decreased from 8.00 to 2.50 days. CONCLUSIONS: Laparoscopic inversion esophagectomy is a safe procedure. The learning curve for the inversion approach is approximately 10 operations in the hands of esophageal surgeons with advanced laparoscopic expertise.

Adenocarcinoma↗