Preimplantation genetic diagnosis of a reciprocal translocation t(3;11)(q27.3;q24.3) in siblings.
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Preimplantation genetic diagnosis (PGD) was performed in two couples to avoid chromosomally unbalanced progeny in a family in which a brother and a sister carry an identical maternally inherited balanced translocation t(3;11)(q27.3;q24.3). Embryos were biopsied 3 days after fertilization and blastomeres were analysed by fluorescent in-situ hybridization (FISH). Embryos were classified as unbalanced or normal/balanced. In the first case, the male carrier and his wife underwent one IVF/PGD treatment cycle. In all, 18 embryos were analysed. Of those, 15 revealed an unbalanced karyotype. For one embryo, results were not conclusive, from one embryo results were contradictory and one embryo was classified as normal/balanced and subsequently transferred. A singleton pregnancy was achieved. The PGD analysis was confirmed at 16 weeks gestation by amniocentesis. At term, a healthy girl with a balanced karyotype was born. Pregnancy and delivery were without complications. In the second case, the female carrier and her husband underwent two IVF/PGD treatment cycles. During the first cycle, three embryos were analysed. One embryo revealed an unbalanced karyotype and two embryos were designated a normal/balanced karyotype and transferred but no pregnancy was achieved. During the second PGD cycle three embryos were analysed. Of those, none appeared suitable for transfer. The couple decided not to undergo further treatment. Our results indicate that for individuals carrying a reciprocal translocation PGD is a feasible approach to obtain embryos with a normal chromosome balance and to avoid both spontaneous and induced abortion. (+info)
Molecular analysis of phyllodes tumors reveals distinct changes in the epithelial and stromal components.
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Phyllodes tumors are fibroepithelial mammary lesions that tend to behave in a benign fashion but may undergo sarcomatous transformation. A study of clonality in these tumors has suggested that the epithelial component is polyclonal, but the stroma is monoclonal, and thus forms the neoplastic component of the lesion. In this study microsatellites on chromosome 1q and chromosome 3p were assessed for allelic imbalance (AI) in 47 phyllodes tumors; in all cases stroma and epithelium were analyzed separately. Ten of 42 (24%) phyllodes tumors showed AI at one or more markers on 3p, and 14 of 46 (30%) showed AI on chromosome 1. Five tumors had changes in both the epithelium and stroma. Eight tumors had changes only detectable in the stroma and eight, changes in the epithelium only. Three tumors exhibited low-level microsatellite instability in the epithelium but not in the stroma. The results show that AI on 3p and 1q does occur in phyllodes tumors and that it can occur in both the stroma and epithelium, sometimes as independent genetic events. These unexpected findings throw into doubt the classical view that phyllodes tumors are simply stromal neoplasms and raise questions about the nature of stromal and epithelial interactions in these tumors. (+info)
HYAL1LUCA-1, a candidate tumor suppressor gene on chromosome 3p21.3, is inactivated in head and neck squamous cell carcinomas by aberrant splicing of pre-mRNA.
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The hyaluronidase first isolated from human plasma, Hyal-1, is expressed in many somatic tissues. The Hyal-1 gene, HYAL1, also known as LUCA-1, maps to chromosome 3p21.3 within a candidate tumor suppressor gene locus defined by homozygous deletions and by functional tumor suppressor activity. Hemizygosity in this region occurs in many malignancies, including squamous cell carcinomas of the head and neck. We have investigated whether cell lines derived from such malignancies expressed Hyal-1 activity, using normal human keratinocytes as controls. Hyal-1 enzyme activity and protein were absent or markedly reduced in six of seven carcinoma cell lines examined. Comparative genomic and fluorescence in situ hybridization identified chromosomal deletions of one allele of HYAL1 in six of seven cell lines. Initial RT - PCR analyses demonstrated marked discrepancies between levels of HYAL1 mRNA and protein. Despite repeated sequence analyses, no mutations were found. However, two species of transcripts were identified when primers were used that included the 5' untranslated region. The predominant mRNA species did not correlate with protein translation and contained a retained intron. A second spliced form lacking this intron was found only in cell lines that produced Hyal-1 protein. Inactivation of HYAL1 in these tumor lines is a result of incomplete splicing of its pre-mRNA that appears to be epigenetic in nature. Oncogene (2000) 19, 870 - 877. (+info)
Chromosomal aberrations evaluated by CGH, FISH and GTG-banding in a case of AIDS-related Burkitt's lymphoma.
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BACKGROUND AND OBJECTIVE: We have previously reported on a complex chromosome rearrangement [der(17)] in a B-cell line, BRG A, established from an AIDS patient with Burkitt's lymphoma (BL). The aim of the present study was the definition of der(17) composition and the identification of complete or partial chromosome gains and losses in two cell clones (BRG A and BRG M) derived from this patient. DESIGN AND METHODS: We applied comparative genome hybridization (CGH) to detect the DNA misrepresentations in the genome of the two cell clones. Findings from CGH and banding analysis could then direct the choice of probes for chromosome painting experiments to elucidate der(17) composition. RESULTS: CGH analysis identified gains of chromosomes 1q, 7q, 12q, 13q, 15q, 17p, 20p,q and losses of chromosomes 3p and 5q in BRG A and gain of chromosome 1q and loss in chromosome 6q in BRG M. Some of the detected alterations had already been described in lymphomas, while others appeared to be new. The combination of these techniques allowed a precise definition of der(17), composed by translocated regions from chromosomes 12 and 15. INTERPRETATION AND CONCLUSIONS: We demonstrated CGH to be a powerful tool in the identification of recurrent chromosome aberrations in an AIDS-related BL and in ascertaining the origin of marker chromosomes. We were also able to identify a different pattern of aberrations and assess an independent sequence of events leading to the 1p gain in the two subclones. (+info)
Alterations of the FHIT gene in human hepatocellular carcinoma.
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FHIT (fragile histidine triad), a candidate tumor suppressor gene, encompasses FRA3B, a region with the highest fragility in the human genome, and is altered in a large number of human cancers, particularly those of epithelial cell origin and associated with known carcinogenic agents. Human hepatocellular carcinoma (HCC), a major cancer worldwide, is closely related to carcinogenic agents such as hepatitis B and C virus infections, dietary aflatoxin, alcohol consumption, and exposure to chemical carcinogens. To assess the extent and the nature of the FHIT gene alterations and their implications in the development of HCC, several cell lines and primary tumors were cytologically and molecularly examined. The FHIT gene is expressed in normal hepatic cells and is not expressed or is abnormally expressed in cultured tumor cells derived from HCC. Down-regulation of the FHIT gene was detected by Northern blot analysis in 9 of 14 cell lines However, neither abnormal FHIT transcripts nor point mutations in DNA sequences of reverse transcription-PCR products (exons 2-9) were identified. Expression of FHIT protein was not detected by immunostaining in 5 of 10 primary tumors. Four cell lines showing mRNA down-regulation did not express FHIT protein as demonstrated by Western blot analysis. Allelic loss of intron 5 of the FHIT gene was detected in 10 of 34 informative samples from primary tumors. Structural alterations of chromosome 3p were identified in 8 of 13 HCC cell lines. Deletions or translocations involving region 3p14.2 were identified by fluorescence in situ hybridization with a YAC850A6 probe spanning the FHIT locus on chromosomes derived from cell lines with an abnormal FHIT gene expression. These combined results indicate that the FHIT gene is a frequent target and may be implicated in a subset of liver cancers. (+info)
Two new loci for autosomal recessive ichthyosis on chromosomes 3p21 and 19p12-q12 and evidence for further genetic heterogeneity.
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Autosomal recessive ichthyosis (ARI) includes a heterogeneous group of disorders of keratinization characterized by desquamation over the whole body. Two forms largely limited to the skin have been defined: lamellar ichthyosis (LI) and nonbullous congenital ichthyosiform erythroderma (NCIE). A first gene for LI, transglutaminase TGM1, has been identified on chromosome 14, and a second one has been localized on chromosome 2. In a genomewide scan of nine large consanguineous families, using homozygosity mapping, two new loci for ARI were found, one for a lamellar form in a 6-cM interval on chromosome 19 and a second for an erythrodermic form in a 7.7-cM interval on chromosome 3. Linkage to one of the four loci could be demonstrated in more than half of 51 consanguineous families, most of them from the Mediterranean basin. All four loci could be excluded in the others, implying further genetic heterogeneity in this disorder. Multipoint linkage analysis gave maximal LOD scores of 11.25 at locus D19S566 and 8.53 at locus D3S3564. (+info)
Combined LOH/CGH analysis proves the existence of interstitial 3p deletions in renal cell carcinoma.
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We have recently developed an allele titration assay (ATA) to assess the sensitivity and influence of normal cell admixture in loss of heterozygosity (LOH) studies based on CA-repeat. The assay showed that these studies are biased by the size-dependent differential sensitivity of allele detection. Based on these data, we have set up new criteria for evaluation of LOH. By combining these new rules with comparative genome hybridization (CGH) we have shown the presence of interstitial deletions in renal cell carcinoma (RCC) biopsies and cell lines. At least three out of 11 analysed RCC cell lines and three out of 37 biopsies contain interstitial deletions on chromosome 3. Our study suggests the presence of several regions on human chromosome 3 that might contribute to tumor development by their loss: (i) 3p25-p26, around the VHL gene (D3S1317); (ii) 3p21. 3-p22 (between D3S1260 and D3S1611); (iii) 3p21.2 (around D3S1235 and D3S1289); (iv) 3p13-p14 (around D3S1312 and D3S1285). For the first time, AP20 region (3p21.3-p22) was carefully tested for LOH in RCC. It was found that the AP20 region is the most frequently affected area. Our data also suggest that another tumor suppressor gene is located near the VHL gene in 3p25-p26. (+info)
The p44S10 locus, encoding a subunit of the proteasome regulatory particle, is amplified during progression of cutaneous malignant melanoma.
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Gene amplification is frequently present in human tumors, although specific target genes relevant to many amplified loci remain unidentified. An expression cloning assay enabled identification of a candidate oncogene derived from human chromosome 3p14.1. The cDNA retrieved from morphologically transformed cells contained the full-length protein coding region and detected an abundant transcript in the same cells. Sequence analysis revealed identity with the wild-type sequence of p44S10, a highly conserved subunit of the 26S proteasome that exhibits similarity to the Arabidopsis fus6/cop11 family of signaling molecules. p44S10 gene copy number and mRNA expression were increased in association with segmental 1.8 - 11-fold chromosomal gains in cutaneous malignant melanoma cell lines (5/13; 40%) and tumors (2/40; 5%), and in breast cancer MCF-7 cells. Likewise, malignant progression of human radial growth phase WM35 melanoma cells was associated with amplification and increased expression of endogenous p44S10, and increased expression of p44S10 was sufficient to induce proliferation of WM35 cells in vivo. The results demonstrate segmental copy number gains within chromosome 3p in cutaneous malignant melanoma and suggest that deregulation of a proteasome regulatory particle subunit may contribute to the malignant phenotype. (+info)