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PubMed2006

TEM, FISH and molecular studies in infertile men with pericentric inversion of chromosome 9.

Pericentric inversions involving the secondary constriction (qh) region of chromosome 9 are considered to be normal variants of human karyotype. A number of investigators have suggested that chromosomal anomalies can contribute to human infertility causing spermatogenetic derangement. The present study was aimed at verifying the influence of chromosome 9 inversion on human spermatogenesis. Semen samples of 18 male carriers of chromosome 9 inversion, analysed by light microscopy, revealed that five patients were azoospermic. PCR analysis demonstrated that two of them also had Y microdeletions. The other 13 showed generally normal sperm concentrations and reduced motility. The morphological characteristics of sperm were studied by TEM and the data were elaborated by a mathematical formula. Sperm pathologies resulted more frequently in the studied group compared to controls, particularly apoptosis. Partial sequences of the A-kinase anchoring protein (Akap) 4 and 3 genes were performed in all patients, as a previous study by our group highlighted Dysplasia of Fibrous Sheath (DFS) defect in two men with inv 9 investigations. The possible effect of chromosome 9 inversion on meiotic chromosome segregation was investigated by FISH, which showed an increased incidence of diploidy. We hypothesized that this inversion could have variable effects on spermatogenesis, from azoospermia to severely altered sperm morphology, motility and meiotic segregation.

Adolescent↗
PubMed1998

Chromosomal structure and recombination between inversions in Drosophila subobscura.

Drosophila subobscura is a species with rich chromosomal polymorphism. More than 45 arrangements have been described in the O chromosome. The recombination between them is an interesting topic, because many nonoverlapping arrangements are inherited together. In the analysis of recombination between the arrangements O7 and O3 + 4 + 8, out of 415 individuals observed none was found to be recombinant. The same result was obtained in the study of the recombination between the inversions O5 and O3 + 4, in which 437 individuals were analyzed. In this case a significant non equivalent segregation was found, the O5 chromosomes being more frequent than expected. This phenomenon could be explained by three hypotheses: a meiotic drive, a greater fitness of the individuals carrying this inversion and heterotic effect of a wild chromosome in combination with a chromosome from an inbred laboratory strain. If the second hypothesis is correct, it could explain why an inversion always associated with a lethal gene in American populations is not infrequent and presents a clinal distribution in the colonized areas. Furthermore, another inversion, O22, is very similar to O5. These two inversions can be distinguished only by careful observation. Although O22 and O5 are very similar they show different behavior in the wild, probably due to the combinations of genes included in them.

Animals↗
PubMed1999

Generation of a widespread Drosophila inversion by a transposable element.

Although polymorphic inversions in Drosophila are very common, the origin of these chromosomal rearrangements is unclear. The breakpoints of the cosmopolitan inversion 2j of D. buzzatii were cloned and sequenced. Both breakpoints contain large insertions corresponding to a transposable element. It appears that the two pairs of target site duplications generated upon insertion were exchanged during the inversion event, and that the inversion arose by ectopic recombination between two copies of the transposon that were in opposite orientations. This is apparently the mechanism by which transposable elements generate natural inversions in Drosophila.

Animals↗
PubMed1994

Inversions and deletions generated by a mini-gamma delta (Tn1000) transposon.

Intramolecular transposition by an engineered derivative of the transposon gamma delta (Tn1000) is described. This 1-kb element contains inverted repeats of the 40 bp of the delta end of gamma delta, bracketing a kan gene, but it contains no resolution site. Transposition was analyzed in two plasmids; one contained two contraselectable (conditional lethal) genes (thyA and sacB) adjacent to the mini-gamma delta element in a 13.0-kb pBR322/pUC-based two-component plasmid (a heterodimer), and the other contained a different contraselectable gene (strA [rpsL]) in a 13.2-kb three-component plasmid (a heterotrimer). Selection for loss of function of a single contraselectable gene yielded inversions and deletions. Each inversion plasmid was 1 kb larger than the parent plasmid: it had a second copy of mini-gamma delta inserted in the contraselected gene, with that copy plus the intervening segment inverted, and the 5-bp target site duplicated. Each deletion plasmid was smaller than the parent plasmid and had a deletion that extended from one transposon end into or through the contraselected gene for distances of up to 9.4 kb. The frequencies of deletions versus inversions ending in a single target gene were similar, although overall, deletions outnumbered inversions because deletions, but not inversions, into sites beyond the contraselected gene inactivate it. This work also demonstrates that thyA (which encodes thymidylate synthetase) is a useful contraselectable marker.

Base Sequence↗
PubMed1987

Pericentric inversion in human chromosome 1 and the risk for male sterility.

A pericentric inversion in chromosome 1 of a severely oligospermic human male is reported. Pachytene analysis in microspread preparations shows an absence of full loop formation in the inversion bivalent and only the rare occurrence of a partial loop. The majority of cells exhibit extensive asynapsis across the inverted segment, or a normal looking synaptonemal complex indicative of heterologous pairing along the length of the inversion. Crossing over is reduced in the No 1 bivalent with only a rare chiasma being seen in the inverted region at metaphase I. Males heterozygous for a pericentric inversion in chromosome 1 appear to be at severe risk for infertility brought about by spermatogenic disturbance. The dearth of full loops at prophase in this patient, and in other pericentric inversion cases studied both in man and other species, raises the question of whether recombinant offspring might be rarer than anticipated on a theoretical basis owing to asynapsis or early heterologous synapsis across inverted segments.

Adult↗
PubMed1990

Inversion polymorphism in Indian natural populations of Drosophila melanogaster.

Six natural populations (three urban and three rural) of Drosophila melanogaster from India were analysed for chromosome inversions, revealing the presence of 19 different paracentric autosomal inversions. One new inversion has also been detected in a laboratory stock established from flies collected from Kerala. In total 20 different paracentric inversions in Indian D. melanogaster have been detected during the present study, and of these, 4 are common cosmopolitans; 2 are rare cosmopolitans; 7 are recurrent endemics; and 7 are unique endemics. The quantitative data clearly show that the urban populations are different from the rural ones with respect to inversion polymorphism.

Animals↗
PubMed2006

Non-puerperal uterine inversion due to uterine sarcoma.

BACKGROUND: Uterine inversion is a very rare pathological condition that usually occurs in puerperium. Non- puerperal uterine inversion is exceptional and to our knowledge only a few cases of uterine inversion due to a uterine sarcoma have been reported. CASE REPORT: A 79-year-old woman, gravida 0, para 0, presented with vaginal bleeding. Pelvic examination under anesthesia revealed a huge mass coming from the cervix filling the vagina to the introitus, and rectal examination could not identify the uterus. Diagnosis of uterine inversion was made and the patient was submitted to total abdominal hysterectomy with bilateral salpingo-oophorectomy and pelvic lymph node sampling. The postoperative course was uneventful and the patient was discharged on the 5th postoperative day. She underwent postoperative pelvic radiation, and no recurrence was found during the 19-month follow-up period. CONCLUSION: Chronic non-puerperal uterine inversion can be considered a rare complication of malignant mixed mullerian tumor of the uterus.

Aged↗
PubMed1981

A pericentric inversion in the mouse.

A pericentric inversion induced in a Robertsonian chromosome was recovered and analyzed in a male heterozygous for the rearrangement. Identification was made from chromosome banding and confirmed by synaptonemal complex(SC) analyses. From the former, the chromosome was identified as Rb4Bnr. The inversion involves about 34% of the chromosome length, and is designated In(11.13LS)29Rk. Analysis of SC inversion loops gave break points at 0.20 in the short arm and 0.54 in the long arm. Inhibition of homologous synapsis in the inversion was observed at zygotene and early pachytene, while synaptic adjustment was found to lead to heterologous SC formation at late pachytene. The inversion is believed to be causally related to the reduction in fertility observed in the carriers.

Animals↗
PubMed1995

Male sterility and double heterozygosity for chromosomal inversion.

A meiotic analysis has been carried out on male mice heterozygous for one of two inversions in Chromosome 2, In(2)5Rk and In(2)2H, as well as on double heterozygotes for these two overlapping inversions. Electron microscopic observation of synaptonemal complexes revealed that heterosynapsis had occurred in a large number of spermatocytes, producing a small number of cells with an inversion loop. Heterozygous carriers of a single inversion loop reproduced quite normally, whereas doubly heterozygous carriers of a double loop showed a reduction in spermatogenesis. These data shed new light on the role of inversions in speciation.

Animals↗
PubMed1996

A new method for detecting pericentric inversions using COD-FISH.

A new approach for detecting chromosomal inversions, based on the recently developed technique of chromosome orientation and direction fluorescence in situ hybridization (COD-FISH), is presented. COD-FISH is a strand-specific modification of standard FISH technology which allows the hybridization of single-stranded probes to one, and only one, chromatid of a metaphase chromosome. It can be used to determine the absolute 5'-to-3' direction of DNA target sequences with respect to the short-to-long arm direction of a given chromosome. Since an inversion reverses the orientation of DNA sequences within the inverted region, an inversion becomes detectable as a "switch" in probe signal from one chromatid to the other, when compared to a reference probe outside of the inverted region. Pericentric inversions in chromosomes 1, 8, 10, and X, which had previously been identified by chromosome banding, were analyzed by the COD-FISH technique. The results presented here demonstrate that COD-FISH can be used for the detection of pericentric inversions and that, in some instances, it provides additional information not obtainable by more conventional methods of cytogenetic analysis. Practical limitations of the COD-FISH technique are also discussed.

Centromere↗
PubMed2003

Refinement of a chimpanzee pericentric inversion breakpoint to a segmental duplication cluster.

BACKGROUND: Pericentric inversions are the most common euchromatic chromosomal differences among humans and the great apes. The human and chimpanzee karyotype differs by nine such events, in addition to several constitutive heterochromatic increases and one chromosomal fusion event. Reproductive isolation and subsequent speciation are thought to be the potential result of pericentric inversions, as reproductive boundaries form as a result of hybrid sterility. RESULTS: Here we employed a comparative fluorescence in situ hybridization approach, using probes selected from a combination of physical mapping, genomic sequence, and segmental duplication analyses to narrow the breakpoint interval of a pericentric inversion in chimpanzee involving the orthologous human 15q11-q13 region. We have refined the inversion breakpoint of this chimpanzee-specific rearrangement to a 600 kilobase (kb) interval of the human genome consisting of entirely duplicated material. Detailed analysis of the underlying sequence indicated that this region comprises multiple segmental duplications, including a previously characterized duplication of the alpha7 neuronal nicotinic acetylcholine receptor subunit gene (CHRNA7) in 15q13.3 and several Golgin-linked-to-PML, or LCR15, duplications. CONCLUSIONS: We conclude that, on the basis of experimental data excluding the CHRNA7 duplicon as the site of inversion, and sequence analysis of regional duplications, the most likely rearrangement site is within a GLP/LCR15 duplicon. This study further exemplifies the genomic plasticity due to the presence of segmental duplications and highlights their importance for a complete understanding of genome evolution.

Animals↗
PubMed1994

On the category of naturally occurring inversions of Drosophila melanogaster.

The categorization of naturally occurring inversions in Drosophila melanogaster made by Mettler et al. (1977) was re-examined through compilation of recent data from the world-wide investigations. Categorization was changed into 5 classes by adding a new class: Common cosmopolitan, Rare cosmopolitan, Quasi cosmopolitan, Endemic and Unique. Modifications were also proposed: (1) The Rare cosmopolitans were limited to the 3 inversions, In(3L)M, In(3R)C and In(3R)Mo, instead of 8 inversions originally included. (2) Ambiguity between Endemic and Unique was noted and discussed. Data were presented to show that repeated surveys of the usual scale in a natural population indeed detected Endemic inversions which otherwise would have been classified as Unique inversions. More recent data on Japanese natural populations were finally presented. The Common cosmopolitans but not the Rare and Quasi cosmopolitans clearly showed high frequencies in the south.

Animals↗
PubMed1999

Rare interstitial deletion (2)(p11.2p13) in a child with pericentric inversion (2)(p11.2q13) of paternal origin.

An unbalanced 46,XY,der(2)del(2)(p11.2p13) inv(2)(p11.2q13) karyotype was found in a phenotypically abnormal child with a de novo interstitial deletion of band 2p12 associated with an inv(2)(p11.2q13) inherited from the father. The inv(2) is generally considered a benign familial variant without significant reproductive consequences. However, our findings led us to consider a previously proposed mechanism of unequal meiotic crossing over at the base of a parental inversion loop, which could lead to either a deletion or duplication of a segment adjacent to the inverted region in the offspring. This phenomenon has been reported in other inversions of chromosomes 1, 7, 13, 15, and 17 and may explain the origin of the deletion in our patient. Although repetitive sequences might be present around such inversions, which could predispose to de novo deletions independently of the inversion, current evidence including this case favors a proposed causal relationship between the parental inversion and the deletion in the child. Our review and results suggest there could be a small risk for a related imbalance to couples with an inv(2)(p11.2q13). For del(2)(p11.2p13), which is rare, a more distinct phenotype has been proposed herein. Our patient shared several findings with the three previously published cases, namely the broad nasal bridge, abnormal ears, high-arched palate, psychomotor retardation, and micrognathia. However, our patient also had sensorineural hearing loss and significant hypotonia, which have not been previously reported, thereby expanding our understanding of this rare deletion. Am. J. Med. Genet. 87:139-142, 1999. Published 1999 Wiley-Liss, Inc.

Abnormalities, Multiple↗
PubMed2000

De novo factor VIII gene intron 22 inversion in a female carrier presents as a somatic mosaicism.

The intron 22 inversion represents the most prevalent factor VIII gene defect in severe hemophilia A, accounting for about 40% of all mutations. It is hypothesized that the inversion mutations occur almost exclusively in germ cells during meiotic cell division by intrachromosomal recombination between 1 of 2 telomeric copies of the Int22h region and its intragenic homologue. The majority of inversion mutations originate in male germ cells, where the lack of bivalent formation may facilitate flipping of the telomeric end of the single X chromosome. This is the first intron 22 inversion that presents as a somatic mosaicism in a female, affecting only about 50% of lymphocyte and fibroblast cells of the proposita. Supposing a post-zygotic de novo mutation as the usual cause of somatic mosaicism, the finding would imply that the intron 22 inversion mutation is not restricted to meiotic cell divisions but can also occur during mitotic cell divisions, either in germ cell precursors or in somatic cells. (Blood. 2000;96:2905-2906)

Adult↗
PubMed2000

Chromosomal inversion polymorphism of Anopheles funestus from forest villages of South Cameroon.

The polymorphism of paracentric inversions of Anopheles funestus polytene chromosomes was studied in three villages (Nkoteng, Obala, and Simbock) located in a forest area of South Cameroon in order to analyse the genetic structure of these populations. A total of 146-210 chromatids could be scored from specimens collected over about two years. A low degree of chromosomal polymorphism was observed with two floating inversions on chromosomal arm 2 (2h and 2d), and three fixed arrangements on arms 3 (3a and 3b), and 5 (5a). Such arrangement of inversions has never been recorded elsewhere so far. The chromosome analysis indicated that the population from Obala was in Hardy-Weinberg equilibrium, whereas the samples from Nkoteng and Simbock showed a significant excess and deficit of heterokaryotypes, respectively. Significant differences in inversion frequencies on chromosomal arm 2 among villages lying in contrasting eco-climatic settings suggested an adaptive role of these inversions.

Animals↗
PubMed2002

The prothrombin 20210A allele influences clinical manifestations of hemophilia A in patients with intron 22 inversion and without inhibitors.

BACKGROUND AND OBJECTIVES: The modulation of disease severity in hemophilia A (HA) patients may be related to the co-inheritance of mutations in genes with a known thrombotic effect such as factor V Leiden (FVL) and prothrombin. In the Spanish population, the prothrombin 20210A (PT20210A) allele is the most prevalent genetic risk factor for venous thromboembolism. DESIGN AND METHODS: We investigated the presence of both mutations in a cohort of 265 hemophiliac patients divided into two groups: I) 140 unrelated patients with moderate and mild HA and II) 125 unrelated patients with severe HA (83 carrying an inversion of intron 22). RESULTS: In group I, 4 patients had the FVL (2.8% vs. 2.98% controls) and 5 had the PT20210A (3.6% vs. 6.46% controls). In group II, two patients with inversion had the FVL (1.6%) and PT20210A was found in 10 patients (8%), five of them with inversion of intron 22 without inhibitors. One of these patients had the FVL and PT20210A mutations concomitantly. In the subgroup of patients with inversion who were carriers of the PT20210A, three parameters i.e. spontaneous bleeding (p=0.008), factor VIII utilization (p=0.016) and number of hemophilic arthropathies (p<0.0005) were significantly lower than in a subgroup of 11 age-matched non-PT20210A severe HA patients with inversion and without inhibitors. INTERPRETATION AND CONCLUSIONS: These results indicate that the inheritance of PT20210A could be a protective factor that mitigates the clinical severity of HA.

Adolescent↗
PubMed2001

Patterns of inversion polymorphism in three species of the Drosophila melanogaster species group.

In Drosophila, chromosomal polymorphism due to paracentric inversions is very common and constitutes an adaptive character. The degree of chromosomal variability varies in different species and also in different populations of the same species. Chromosomal polymorphism in Indian natural populations of three species, D. melaonogaster, D. ananassae and D. bipectinata which belong to the melanogaster species group has been studied and the quantitative data on frequency of inversions have been reported. Behaviour of chromosome inversions has also been studied in laboratory conditions. The present review summarises the work done on inversion polymorphism in Indian populations of three species which clearly demonstrates that these three species vary in their patterns of inversion polymorphism and have evolved different mechanisms for adjustment to their environments although they belong to the same species group.

Animals↗
PubMed2002

[Acute puerperal uterine inversion: two cases].

Acute puerperal inversion is both rare and serious (1/20000 deliveries in France) and may lead to significant morbidity and mortality. Outcome depends on the degree of uterine bleeding and the presence or not of a state of shock. Acute puerperal inversion occurs at the time of placental delivery. Four stages are usually described by degree of exteriorization of the uterus. The diagnosis is essentially clinical. The predisposing factors are hypotonic uterus, fundal implantation of the placenta and placental acretas. 60% of all cases are caused by precipitous manoeuvres including traction on the cord or improper fundal pressure. Once a diagnosis is made immediate measures must be undertaken to assure clinical stability of the mother. Manuel reinversion of the uterus must be done quickly to avoid a cervical stricture that may form within thirty minutes of the inversion making successful manipulation very difficult. Failure or reoccurrence requires surgical treatment either by abdominal or vaginal approach. We report on two cases: one of complete inversion leading to a hysterectomy in order to control bleeding and a second case of incomplete inversion where repositioning was successful.

Acute Disease↗