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E Blennow

Publications and source records attributed to E Blennow.

At least 37 records · Page 2Linked to original sources
PubMed2000

Fine mapping of the constitutional translocation t(11;22)(q23;q11).

Translocation t(11;22)(q23;q11) is the most common constitutional reciprocal translocation in man. Balanced carriers are phenotypically normal, except for decreased fertility, an increased spontaneous abortion rate and a possible predisposition to breast cancer in some families. Here, we report the high resolution mapping of the t(11;22)(q23;q11) breakpoint. We have localised the breakpoint, by using fluorescence in situ hybidisation (FISH) walking, to a region between D11S1340 and WI-8564 on chromosome 11, and D22S134 and D22S264 on chromosome 22. We report the isolation of a bacterial artificial chromosome (BAC) clone spanning the breakpoint in 11q23. We have narrowed down the breakpoint to an 80-kb sequenced region on chromosome 11 and FISH analysis has revealed a variation of the breakpoint position between patients. In 22q11, we have sequenced two BACs (BAC2280L11 and BAC41C4) apparently mapping to the region; these contain low copy repeats (LCRs). Southern blot analysis with probes from BAC2280L11 has revealed different patterns between normal controls and translocation carriers, indicating that sequences similar/identical to these probes flank the translocation breakpoint. The occurrence of LCRs has previously been associated with genomic instability and "unclonable" regions. Hence, the presence of such repeats renders standard translocation breakpoint cloning techniques ineffective. Thus, we have used high resolution fiber-FISH to study this region in normal and translocation cases by using probes from 22q11, LCRs and 11q23. We demonstrate that the LCR containing the gap in 22q11 is probably substantially larger than the previous estimates of 100 kb. Using fiber-FISH, we have localised the breakpoint in 22q11 to approximately 20-40 kb from the centromeric border of the LCR (i.e. the telomeric end of AC006547) and have confirmed the breakpoint position on 11q23.

Base Sequence↗
PubMed2000

Inv dup(22), del(22)(q11) and r(22) in the father of a child with DiGeorge syndrome.

We here report a unique inherited case of DiGeorge syndrome. The asymptomatic father had a mosaic karyotype with a 21q11 deletion in three different cell lines. In two of the cell lines there was an additional supernumerary inv dup(22) or an r(22), respectively. In the third cell line the del(22) was the sole anomaly. FISH analysis showed that both the inv dup(22) and the r(22) included the DGS region. We hypothesize that an inter-chromosomal recombination between inverted repeats, together with a recombination between sister chromatids during meiosis I, gave rise to a deletion of 22q11 as well as an inv dup(22) containing the DGS region. The inv dup(22) was later rearranged into a ring chromosome during mitosis which was subsequently lost during cell division, thereby resulting in three different cell lines. This is the first case reported with an inv dup(22) and a del(22)(q11) in the same cell line. Our findings support a related mechanism in the formation of these two rearrangements mediated by low-copy repeats.

Adult↗
PubMed2000

Detailed characterization of a complex karyotype in a patient with primary plasma cell leukaemia using multicolour spectral karyotyping and micro-FISH.

INTRODUCTION: Plasma cell leukaemia is a rare disorder that usually carries an aggressive course with a rapidly fatal outcome. A variety of chromosomal abnormalities have been reported in plasma cell leukaemia but the clinical significance of an abnormal karyotype is still unclear. MATERIALS AND METHODS: We have applied the molecular cytogenetic techniques multicolour spectral karyotyping and microdissection in combination with fluorescence in situ hybridization on metaphases from a patient with primary plasma cell leukaemia and a fatal outcome. RESULTS AND CONCLUSION: The chromosome analysis showed severe hypodiploidy and 12 marker chromosomes. Identification of the structural rearrangements was not possible using routine cytogenetic methods. Utilizing the methods above, all marker chromosomes could be identified in detail and the karyotype was shown to be very complex. Forty-three breakpoints were found, and 25 could be identified at the band level, among others 14q32 where the immunoglobulin heavy chain locus is situated. Thus, these techniques provide the opportunity to resolve very complex chromosomal changes in a way that has not been previously possible and will consequently be of great importance in the search for hot spots that may harbour new cancer genes.

Adult↗
PubMed2000

New chromosomal breakpoints in non-Hodgkin's lymphomas revealed by spectral karyotyping and G-banding.

Chromosomal rearrangements in short term cultures from nine cases of non-Hodgkin's lymphomas (NHL) were characterized by G-banding, spectral karyotyping (SKY), and fluorescence in situ hybridization (FISH). Eight of the nine cases showed complex karyotypes with chromosomal aberrations which, in most cases, could not be fully characterized by traditional G-banding analysis alone. Karyotypic abnormalities of special interest were marker chromosomes and chromosomes with added unidentified chromosomal material, as previously non-identified chromosomal translocations were hidden behind these aberrations. SKY and FISH analysis, as a complement to banding analysis, significantly improved the karyotypes in seven of the nine cases and unveiled 21 previously unidentified rearrangements with novel translocation breakpoints. Traditional G-banding alone revealed seven new rearrangements, which were all confirmed by SKY. None of these new aberrations occurred as single clonal rearrangements but as parts of complex karyotypes. Nevertheless, the chromosomal break-point regions identified should be considered as potential hot spots for genes involved in the tumorigenesis of the malignancy.

Adult↗
PubMed2000

Highly abnormal cleavage divisions in preimplantation embryos from translocation carriers.

We have developed preimplantation genetic diagnosis (PGD) for carriers of chromosomal abnormalities using fluorescent in situ hybridisation (FISH). Here we present the detailed analysis of 64 biopsied, normally developing embryos obtained from four Robertsonian and three reciprocal translocation carriers in 11 treatment cycles of which four resulted in normal pregnancies (three simplex, one duplex). In order to investigate the degree of mosaicism and segregation mode in the embryos, the primary analysis of the biopsied cells was extended with the analysis of all cells from the non-transferred embryos. The analysis also included a second hybridisation with two additional probes, not involved in the translocation (chromosomes 1 and 9), in order to investigate the overall degree of mosaicism. Seventeen out of 64 analysed embryos were balanced for the chromosomes involved in the translocation and 14 of these were transferred. Forty-seven out of 64 embryos (73%) were mosaic regarding the chromosomes involved in the translocation and alternate segregation mode was the most common mode of segregation. Moreover, we have found a higher degree of mosaicism for the chromosomes involved in translocations as compared to control chromosomes. This difference was more pronounced for the embryos from reciprocal translocation carriers. The results, mechanisms, significance and implications of our findings are discussed.

Biopsy↗
PubMed1999

Maternal isodisomy of chromosome 9 with no impact on the phenotype in a woman with two isochromosomes: i(9p) and i(9q).

We describe a 34-year-old healthy woman with isochromosomes for the short and long arm of chromosome 9 who was ascertained because of repeated spontaneous abortions. Molecular analysis demonstrated maternal uniparental isodisomy for the whole chromosome 9, thus the origin of the isochromosomes was maternal. Because the patient had a normal phenotype, the maternal isodisomy supports the previous assumption that there are no maternally imprinted genes on chromosome 9.

Abortion, Spontaneous↗
PubMed1999

A putative susceptibility locus on chromosome 18 is not a major contributor to human selective IgA deficiency: evidence from meiotic mapping of 83 multiple-case families.

Previous reports of an association between constitutional chromosome 18 abnormalities and low levels of IgA suggested that this chromosome contains a susceptibility locus for selective IgA deficiency (IgAD), the most frequent Ig deficiency in humans. IgAD is genetically related to common variable immunodeficiency (CVID), characterized by a lack of additional isotypes. Our previous linkage analysis of 83 multiple-case IgAD/CVID families containing 449 informative pedigree members showed a significantly increased allele sharing in the chromosome region 6p21 consistent with allelic associations in family-based and case-control studies and provided the evidence for a predisposing locus, termed IGAD1, in the proximal part of the MHC. We have typed the same family material at 17 chromosome 18 marker loci with the average intermarker distance of 7 cM. A total of 7633 genotypes were analyzed in a nonparametric linkage analysis, but none of the marker loci exhibited a significantly increased allele sharing in affected family members. In addition, reverse painting and deletion mapping of a panel of constitutional chromosome 18 deletions/translocations showed the presence of IgA-deficient and IgA-proficient patients with the same abnormality and did not reveal a region commonly deleted. The linkage analysis of chromosome 8 and 21 regions involved in reciprocal translocations t(8;18) and t(18;21), which were identified in two patients lacking IgA, did not disclose a significant allele sharing. Although these results do not exclude the presence of a minor predisposing locus on this chromosome, such a putative locus would confer a population risk of developing IgAD/CVID much lower than IGAD1.

Case-Control Studies↗
PubMed1999

A high degree of aneuploidy in frozen-thawed human preimplantation embryos.

We have studied the chromosomal content in 68 normally fertilised freeze-thawed human embryos of good morphology from 34 patients with an average maternal age of 32,6 years. Forty embryos showed post-thaw cellular division and twenty-eight post-thaw cleavage arrest. After spreading of the embryos on microscope slides, analysis of chromosomes X, Y, 15, 16, 17 and 18 was performed using two rounds of fluorescent in situ hybridisation (FISH). According to the results, the embryos were divided into four groups: (I) normal, all nuclei uniformly diploid, (II) diploid mosaics, normal diploid blastomeres in combination with abnormal blastomeres, (III) abnormal, all nuclei abnormal, (IV) chaotic, the chromosome constitution varies randomly from cell to cell. Approximately 25% of the embryos had normal number of the chromosomes tested, while the majority of the embryos were abnormal. Most of the abnormal embryos were diploid mosaics (57%). This was true for the embryos showing cleavage division as well as the embryos showing cleavage arrest. Our data show a slightly higher incidence of abnormal embryos compared to those obtained with FISH in non-cryopreserved embryos and confirm that the majority of preimplantation embryos fertilised in vitro contain abnormal blastomeres. The results, mechanisms, significance and implications are discussed.

Aneuploidy↗
PubMed1999

Severe phenotype of neurofibromatosis type 2 in a patient with a 7.4-MB constitutional deletion on chromosome 22: possible localization of a neurofibromatosis type 2 modifier gene?

Neurofibromatosis type 2 (NF2) is an autosomal dominant disorder predisposing to multiple neoplastic lesions with the hallmark of schwannoma arising at the eighth cranial nerve. NF2 shows a distinct clinical variability, with a mild and a severe form of the disease. The NF2 gene is mutated in constitutional DNA of affected patients from NF2 families and in sporadic cases. Comprehensive mutation analyses in patients with severe and mild phenotypes revealed mutations in only 34%-66%. In the remaining fraction, the genetic mechanism behind the development of NF2 is unknown. Analyses of germline mutations do not provide a conclusive explanation for the observed clinical heterogeneity of NF2. It can therefore be hypothesized that other factors, e.g., modifier gene(s), contribute to the development of a more severe NF2 phenotype. We report a mentally retarded patient with the severe form of NF2 who displays a 7.4 million base pair deletion on chromosome 22. We performed a full genetic characterization of this case using heterozygozity analysis of 41 markers from chromosome 22, detailed FISH mapping of deletion breakpoints, allelotyping of all other chromosomes, and sequencing of the NF2 gene in tumor DNA. Two genomically large deletions similar in size (700-800 kb), which encompass the entire NF2 gene, have been reported previously in mildly affected NF2 patients. The centromeric breakpoints of these deletions were similar to the centromeric breakpoint in the present case. However, the deletion in our patient extends over a much larger distance toward the telomere of 22q. Our results support the existence of NF2 modifier gene(s) and suggest that such a putative locus maps to a 6.5-MB interval on 22q, between D22S32 and the MB gene.

Adult↗
PubMed1998

Application of single-needle blastomere biopsy in human preimplantation genetic diagnosis.

We have tested and subsequently successfully applied a single-needle approach to obtain blastomere biopsies from human preimplantation embryos for preimplantation genetic diagnosis (PGD). The method was first evaluated in a mouse system and shown to be compatible with a high degree of in vitro and in vivo development of biopsied mouse embryos. Furthermore, we showed that biopsied mouse embryos after transfer to recipient mice underwent implantation, normal development and delivery. Litters were followed through puberty and adulthood and shown to be normal with regard to sexual function and also a panel of biochemical and morphological parameters including organ histology. Successful human preimplantation diagnosis, followed by pregnancies and birth of healthy babies, was established with two out of three couples carrying a risk to transmit chromosomal abnormalities leading to severe disease. This is the first report of the successful use of a single-needle approach in human PGD. Considering its simplicity, we conclude that the single-needle approach is an attractive alternative for biopsies in PGD.

Adult↗
PubMed1998

Bilateral multiple renal oncocytomas and cysts associated with a constitutional translocation (8;9)(q24.1;q34.3) and a rare constitutional VHL missense substitution.

We report here on a patient with bilateral multifocal renal oncocytomas and cysts. Cytogenetic analysis of the patient's lymphocytes revealed a constitutional 46,XY,add (9)(q34.3) karyotype. The rearrangement was further resolved as a constitutional reciprocal t(8;9)(q24.1;q34.3) by microdissection and FISH. Because the 9q breakpoint was located in the same region as the tuberous sclerosis type I locus (TSC1), which is associated with renal tumors, we performed FISH with two TSC1 flanking cosmids that were mapped proximal to the 9q breakpoint, thus excluding its involvement. Loss of heterozygosity (LOH) studies of the tumors revealed LOH in chromosome I, further strengthening the molecular diagnosis of oncocytoma. A previously unreported germline missense substitution, Pro40Arg, in exon I of the VHL gene was also found in the patient's constitutional DNA, adding to the complexity of the genetic profile.

Adenoma, Oxyphilic↗
PubMed1998

Molecular analysis of 1p36 breakpoints in two Merkel cell carcinomas.

Merkel cell carcinoma (MCC) is a rare aggressive neuroendocrine tumor of the skin. Only little information is available on the genetic alterations occurring in this tumor. Cytogenetic studies thus far have not shown recurrent chromosomal changes, although various structural chromosome 1 rearrangements, including deletions, often leading to loss of distal 1p material appear to be frequent. We report on fluorescence in situ hybridization and loss of heterozygosity analyses of an MCC tumor and MCC cell line UISO. The present study has shown that two distinct regions in the most distal band 1p36 on the short arm of chromosome 1 can be implicated in MCC. One region at 1p36.3 was delineated by a distal deletion in the MCC tumor as a result of an unbalanced translocation, resulting in loss of all markers distal to ENO1. This region was previously shown to be deleted in different tumor types including neuroblastoma. In cell line UISO an insertion in 1p36.2 was identified. The insertion breakpoint indicates a second, more proximal, region on 1p involved in MCC. The insertion breakpoint was mapped within a cluster of repetitive tRNA and snRNA genes and thus could coincide with the constitutional 1p36 breakpoint previously reported in a patient with neuroblastoma.

Aged↗
PubMed1998

Characterization of the human synaptogyrin gene family.

Genomic sequencing was combined with searches of databases for identification of active genes on human chromosome 22. A cosmid from 22q13, located in the telomeric vicinity of the PDGFB (platelet-derived growth factor B-chain) gene, was fully sequenced. Using an expressed sequence tag-based approach we characterized human (SYNGR1) and mouse (Syngr1) orthologs of the previously cloned rat synaptogyrin gene (RATSYNGR1). The human SYNGR1 gene reveals three (SYNGR1a, SYNGR1b, SYNGR1c) alternative transcript forms of 4.5, 1.3 and 0.9 kb, respectively. The transcription of SYNGR1 starts from two different promoters, and leads to predicted proteins with different N- and C-terminal ends. The most abundant SYNGR1 a transcript, the 4.5-kb form, which corresponds to RATSYNGR1, is highly expressed in neurons of the central nervous system and at much lower levels in other tissues, as determined by in situ hybridization histochemistry. The levels of SYNGR1b and SYNGR1c transcripts are low and limited to heart, skeletal muscle, ovary and fetal liver. We also characterized two additional members of this novel synaptogyrin gene family in human (SYNGR2 and SYNGR3), and one in mouse (Syngr2). The human SYNGR2 gene transcript of 1.6 kb is expressed at high levels in all tissues, except brain. The 2.2-kb SYNGR3 transcript was detected in brain and placenta only. The human SYNGR2 and SYNGR3 genes were mapped by fluorescence in situ hybridization to 17qtel and 16ptel, respectively. The human SYNGR2 gene has a processed pseudogene localized in 15q11. All predicted synaptogyrin proteins contain four strongly conserved transmembrane domains, which is consistent with the M-shaped topology. The C-terminal polypeptide ends are variable in length, display a low degree of sequence similarity between family members, and are therefore likely to convey the functional specificity of each protein.

Amino Acid Sequence↗
PubMed1998

Preimplantation genetic diagnosis of a large pericentric inversion of chromosome 5.

We report the first established pregnancy using preimplantation genetic diagnosis in order to avoid chromosomal imbalance in the progeny of a woman carrying a large inversion of chromosome 5. This is also the first time where it has been possible to study the distribution of balanced and unbalanced gametes in a female inversion carrier. In total, 23 embryos were biopsied in two separate treatments and analysed by fluorescent in-situ hybridization. Of these, 10 were unbalanced, nine were balanced and for four the analysis was inconclusive. The diagnostic procedure was performed within 3.5 h. This allowed the biopsied embryos to be transferred the same day as the biopsy was taken (day 3). Two embryos were transferred each time, and in the second treatment a twin pregnancy with two chromosomally balanced fetuses was established. Healthy twins were delivered at 34 weeks of gestation.

Adult↗
PubMed1998

Preimplantation genetic diagnosis of DiGeorge syndrome.

We report the first case of preimplantation genetic diagnosis used in order to avoid chromosomal imbalance in the progeny of a woman mildly affected by DiGeorge syndrome and carrier of a microdeletion of chromosome 22q11.2. In total, seven embryos were biopsied in three separate treatments and analysed by fluorescent in-situ hybridization (FISH). Of these, four were carrying the deletion, two were normal and in one the analysis was inconclusive. The diagnostic procedure was performed within 5 h. This allowed the biopsied embryos to be transferred the same day as the biopsy was taken (day 3). Two embryos were transferred in the third treatment, but no pregnancy was established. Patients with a 22q11 microdeletion, who have a 50% risk of transmitting the deletion to their offspring, can now be offered preimplantation genetic diagnosis using FISH for the detection of a 22q11 deletion.

Adult↗
PubMed1997

Trisomy 5q12-->q13.3 in a patient with add(13q): characterization of an interchromosomal insertion by forward and reverse chromosome painting.

We report on a patient with azoospermia, mild mental retardation, and minor physical anomalies. Chromosome analysis demonstrated the presence of additional material on the long arm of one chromosome 13. Forward chromosome painting using chromosome-specific libraries showed an insertion of material from chromosome 5. Further characterization with flow sorting of the aberrant chromosome and amplification by DOP-PCR followed by reverse chromosome painting showed specific trisomy of 5q12-->q13.3.

Adult↗
PubMed1997

Further studies on a male monozygotic triplet with schizophrenia: cytogenetical and neurobiological assessments in the patients and their parents.

We previously described a Swedish set of male schizophrenic monozygotic triplets. In this study the patients as well as their parents were further characterized. By high-resolution chromosomal analysis an extra band at chromosome 15p was found in all the triplets and the father. Microdissection, degenerate oligonucleotide-primed PCR (DOP-PCR) amplification and reverse painting indicates that the extra band probably contains only repetitive DNA sequences with no known effect on the phenotype. Magnetic resonance imaging (MRI) showed similar borderline ventricular enlargement and widened subarachnoid spaces over frontoparietal and basal regions as well as around the pituitary gland (empty sella) in all the triplets. The father also had widened subarachnoid spaces over the frontal and basal regions. The mother had an empty sella indicating widened subarachnoid spaces. All the boys also had a right-sided conductive hearing defect, probably due to malformation and fixation of the ossicular chain. The parents did not present any otological abnormalities. Neuropsychological assessment demonstrated similar marked reductions of attentional, mnestic, and executive functions in all the triplets, but the mother showed a normal pattern. Possible joint etiological mechanisms for the psychological and somatic abnormalities recorded in the triplets are discussed.

Adult↗