Reverse painting of microdissected chromosome 19 markers in ovarian carcinoma identifies a complex rearrangement map

Alterations of chromosome bands 19p13 and 19q13 in the form of added extra material of unknown origin are among the most frequent cytogenetic changes in ovarian carcinomas. To investigate the chromosomal composition of the 19p+ and/or 19q+ markers, we selected for examination 26 ovarian carcinomas which by G-banding had one to four 19p+ and/or 19q+, in total 37 markers. These cases were then subjected to chromosomal microdissection with subsequent reverse painting, which gave informative results on 29 markers. The breakpoints on chromosome 19 were located in both the short (p; n = 15) and the long (q; n = 10) arms, as well as in the centromeric (n = 2) and pericentromeric (n = 6) region. The analysis showed that many chromosomes added material to chromosome 19, but the chromosome arms 11q, 21q, and 22q were particularly common donors. Homogeneously staining regions (hsr) were seen in only three markers, in all of them consisting of 19p material. Eighteen markers were derived from an unbalanced translocation involving chromosome 19. In five markers, chromosome 19 was rearranged with two chromosomes. The most complex marker showed chromosome 19 rearranged with three other chromosomes, i.e., X, 13, and 16. In five markers, all of the additional material stemmed from chromosome 19 itself. This is the first large chromosome microdissection/FISH study of chromosome 19 markers in ovarian carcinomas. A detailed map of the rearrangements should provide clues to the positions of oncogenes and potential fusion genes important in ovarian carcinogenesis.     

Region-specific loss of heterozygosity on chromosome 19 is related to the morphologic type of human glioma

Allelic mutation on chromosome 19 has previously been reported as a frequent genetic event in human glial tumors. In an effort to localize specific regions of importance on this chromosome better, 13 highly polymorphic genetic markers distributed along the length of chromosome 19 were used for evaluation of loss of heterozygosity (LOH) and microsatellite instability in a total of 100 brain tumors, including 75 astrocytomas (55 grade 4; 7 grade 3; 5 grade 2; 6 grade 1; and 2 other), 17 oligodendrogliomas (1 grade 4; 5 grade 3; 10 grade 2; and 1 grade 1), and 8 mixed oligoastrocytomas (MOA) (3 grade 4; 2 grade 3; and 3 grade 2). No microsatellite expansion was observed in these glial tumors for any of the chromosome 19 loci examined. LOH for loci on chromosome 19 was detected in 23/74 informative astrocytomas (31%), 11/17 oligodendrogliomas (65%), and 3/8 MOA (38%). Partial deletion of chromosome 19 occurred more frequently (31/37 cases) than did loss of one whole copy of the chromosome, and a morphology-specific pattern of LOH was observed. In 12/14 (86%) instances of chromosome 19 deletion in oligodendrogliomas and MOA, the 19q arm showed LOH, whereas the 19p arm showed no loss for all informative loci. Conversely, in 17/23 (74%) instances of chromosome 19 deletion in astrocytomas, the 19p arm showed LOH, whereas the 19q arm showed no loss for one or more loci. Thus, loss of 19q and retention of 19p are strongly associated with oligodendroglioma and MOA, whereas loss of 19p and retention of distal 19q is associated with astrocytoma. These data indicate that two or more tumor suppressor genes may reside on chromosome 19, one on 19p important in the development of astrocytomas, and one on 19q important in oligodendrogliomas and MOA.     

Monosomy 19pter and trisomy 19q13-qter in two siblings arising from a maternal pericentric inversion: clinical data and molecular characterization

Pericentric inversions of chromosome 19 are very rare rearrangements. Only one case was shown to have resulted in duplication deficiency in the offspring. We report a familial case of pericentric inversion of chromosome 19 not detectable by standard karyotype and usual subtelomeric FISH probes. This inversion was transmitted in its balanced and in its recombinant form to the offspring. The two children carrying the recombinant chromosome 19 presented with growth and mental retardation, microcephaly, mild facial dysmorphism and clinodactyly. The recombinant chromosome 19 was characterized by FISH and array CGH. It consisted of a 400 kb 19pter deletion and a 6.9 Mb (19q13.33-qter) duplication. This observation supports the recombination risk of pericentric inversion of chromosome 19 and emphasizes the role of molecular cytogenetics techniques in the characterization of chromosome 19 rearrangements.     

Identification of new DNA markers close to the myotonic dystrophy locus.

The most useful markers for the prenatal diagnosis of myotonic dystrophy (DM) are APOC2 and CKM, both of which map proximal to DM. In order to produce other markers useful for DM, we have screened genomic DNA libraries constructed from cell line 20XP3542-1-4, which contains 20 to 30 Mb of human material including APOC2 and CKM. Of 51 human clones identified, seven map to chromosome 17, four to chromosome 8, and nine to chromosome 19, and the remaining 31 were excluded form chromosome 19 but not localised further. Four of the clones from chromosome 19 map distal to CKM and two of these clones (D19S62 and D19S63) are closely linked to DM. Analysis of a family in which a crossover between CKM and DM has occurred shows that neither D19S62 nor D19S63 and DM have recombined, suggesting that D19S62 and D19S63 are either closer to or flanking DM in relation to CKM. Pulsed field gel analysis showed that CKM, D19S62, and D19S63 map to a region of at least 1500 kb.     

Prenatal detection and molecular characterization of a de novo duplication of the distal long arm of chromosome 19

A tandem duplication of the distal long arm of chromosome 19 was identified in a 10 week fetus by analysis of chorionic villi. The fetal karyotype from two primary cultures was 46,XY,dir dup(19)(q13.2q13.4). The origin of the extra material was confirmed by fluorescence in situ hybridization using a chromosome 19 whole chromosome probe. Parental chromosomes were normal, indicating a de novo origin of the extra chromosome material. This is the first case of dup(19q) detected by prenatal diagnosis. Molecular studies demonstrated that the duplication involved a maternal chromosome 19. Am. J. Med. Genet. 71:325–328, 1997. © 1997 Wiley-Liss, Inc.     

Additional dark G-band in the p-arm of chromosome 19 due to a paracentric inversion with a breakpoint in the pericentromeric heterochromatin

Paracentric inversions in chromosome 19 have rarely been described. Here we present an inv(19)(p11p13.1) with a breakpoint in the pericentromeric heterochromatin which leads to an additional dark G-band in the p-arm of chromosome 19. The rearranged chromosome segregated in two generations of a family without any phenotypic effects. A detailed characterization of the inv(19) by molecular cytogenetic techniques is presented.     

Chromatin conformation of the H19 epigenetic mark

Genomic imprinting in mammals is an epigenetic process that results in differential expression of the two parental alleles. The tightly linked murine H19 and Igf2 genes are reciprocally imprinted: H19 is expressed from the maternal chromosome while Igf2 is expressed from the paternal chromosome. A single regulatory region in the 5' flank of the H19 gene has been implicated in silencing both genes. On the paternal chromosome, this region is heavily methylated at CpG residues, leading to repression of the H19 gene. The mechanism by which the same region in an unmethylated state on the maternal chromosome silences Igf2 is less well understood. We have probed the chromatin structure of the region by assessing its sensitivity to nuclease digestion. Two regions of nuclease hypersensitivity that are specific to the maternal chromosome were identified. These coincide with the region that is most heavily methylated on the paternal chromosome. As is the case with paternal methylation, hypersensitivity is present in all tissues surveyed, irrespective of H19 expression. We suggest that the chromatin structure of the maternal 5' flank of the H19 gene may represent an epigenetic mark involved in the silencing of Igf2.      

Familial ring (19) chromosome mosaicism: Case report and review

Ring (19) chromosomal mosaicism has been identified in a 14-month-old girl referred for cytogenetic evaluation due to microcephaly and developmental delay with autistic-like mannerisms. An analysis of her peripheral blood lymphocytes showed a 46,XX,r(19) cell line in 119/121 of cells examined. Of the two remaining cells, one had a normal female chromosome complement and the other showed loss of one of the chromosome 19 homologs. Further analysis by fluorescence in situ hybridization using an all human telomere probe showed the presence of a single hybridization signal on the r(19) chromosome. Subsequent cytogenetic characterization of cells derived from the patient's phenotypically normal mother also demonstrated the presence of a ring 19 chromosome in 4/100 cells. The remaining cells had a normal female chromosome complement. These findings represent the first reported case of familial ring 19 mosaicism. The cytogenetic and clinical findings in these two individuals are discussed in relation to six previously reported cases of de novo ring chromosome 19 mosaicism. © 1996 Wiley-Liss, Inc.     

Additional dark G‐band in the p‐arm of chromosome 19 due to a paracentric inversion with a breakpoint in the pericentromeric heterochromatin

Paracentric inversions in chromosome 19 have rarely been described. Here we present an inv(19)(p11p13.1) with a breakpoint in the pericentromeric heterochromatin which leads to an additional dark G‐band in the p‐arm of chromosome 19. The rearranged chromosome segregated in two generations of a family without any phenotypic effects. A detailed characterization of the inv(19) by molecular cytogenetic techniques is presented. © 2001 Wiley‐Liss, Inc.     

Cytogenetic findings in a case of dedifferentiated chondrosarcoma

Cytogenetic analysis of a case of dedifferentiated chondrosarcoma with a malignant fibrous histiocytoma (MFH) component revealed a near-triploid karyotype with multiple copies of chromosome 7, deletion of chromosome arm 9p, and a derivative chromosome 19 [add(19p)] in each metaphase. Whereas numerical anomalies of chromosome 7 have been frequently reported in chondrosarcoma, deletion 9p and add (19p) have been observed in MFH. A putative MFH tumor suppressor gene could be present in a critical region on chromosome bands 9p21~p22.     

A karyotypic analysis of the lesser Malay chevrotain,Tragulus javanicus (Artiodactyla: Tragulidae)

Chevrotains are small forest-dwelling ruminants of the family Tragulidae. The chromosome number of the lesser Malay chevrotain was determined to be 2n=32, NF=64. G- and Q-banding allowed the identification of homologous chromosomes, and C-banding demonstrated the presence of pericentromeric, telomeric and interstitial constitutive heterochromatin. Q-band comparisons with domestic cattle revealed relatively few monobrachial chromosome band homologies. However, the smallest biarmed autosome of the chevrotain, chromosome 15, was determined to be cytogenetically homologus with the acrocentric chromosome 19 of cattle. A molecular cytogenetic analysis confirmed this putative chromosomal homology. In fact, molecular cytogenetic analyses indicate complete conservation of synteny among mouse deer chromosome 15, domestic cattle chromosome 19, domestic pig chromosome 12 and human chromosome 17. In the light of these molecular cytogenetic data and since mouse deer chromosome 15 is submetacentric and appears homologous in banding to submetacentric chromosome 12 of the domestic pig, these outgroup comparisons indicate that the acrocentric condition of cattle chromosome 19 has been derived by inversion. Since this derivative condition is present in the Antilocapridae, Bovidae, Cervidae and Giraffidae, it is a chromosomal synapomorphy that unites these advance ruminant families within the Artiodactyla.accepted for publication by David C. Ward     

Cloning and sequencing of a t(14;19) breakpoint that involves the Cμ switch region

The t(14;19) is a recurring translocation found in a small number of cases of chronic B-cell leukemia (CLL). We have cloned and sequenced the breakpoint in a patient with a t(14;19) and shown that the breakpoint on chromosome 14 occurred in the Cμ switch region, and that the breakpoint on chromosome 19 occurred in the 5′ untranslated region of the BCL3 gene. This is in contrast to all the other reported cases with a t(14;19) in which the breakpoints on chromosome 14 occurred in the Cαl or Cα2 switch region, and the breakpoints on chromosome 19 occurred upstream of the BCL3 gene. Our results further emphasize the importance of the switch region in the t(14;19) translocation. © 1993 Wiley-Liss, Inc.     

Mitotic and meiotic instability of a telomere association involving the Y chromosome

Constitutional telomere associations and jumping translocations (JTs) are rare events and usually occur post-zygotically. We report a telomere association involving the Y chromosome which "jumped" during meiosis. A 21-year-old woman was referred for amniocentesis due to non-immune hydrops seen in a previous pregnancy. Cytogenetic analysis of the amniocytes showed a 45,X,tas(Y;15)[4]/45,X[16] karyotype with the long arm of the Y chromosome attached to the end of the short arm of chromosome 15. Parental chromosome analyzes revealed a tas(Y;19)[63]/45,X[7] karyotype in the father with Yq attached to the end of the short arm of chromosome 19. A phenotypically normal male was born and blood chromosome analysis confirmed a 45,X,tas(Y;15)[39]/45,X[10]/46,XY[1] karyotype. Two other male children have 46,XY karyotypes, which further demonstrates the instability of the tas(Y;19) in meiosis. Fluorescence in situ hybridization (FISH) analysis with probes for theY-centromere, the Yqh region, the shared Xq/Yq telomere and SRY showed hybridization on the tas(Y;19) and tas(Y;15). A chromosome 19p specific subtelomeric probe showed hybridization to the tas(Y;19) in the father. In addition, a probe for the simple telomeric sequences TTAGGG showed positive hybridization to the junction of the associations. The presence of TTAGGG telomere repeats and unique telomere sequences indicate that the Y;15 and Y;19 associations occur with no detectable loss of any sequences. The interstitial telomere sequences at the junction of the telomere association may explain the mitotic and meiotic instability of the association.     

Array‐CGH analysis of microdissected chromosome 19 markers in ovarian carcinoma identifies candidate target genes

Alterations of chromosome 19 are among the most frequent cytogenetic changes in ovarian carcinomas. They usually occur as added extra material of unknown origin to 19p or, less frequently, 19q but sometimes as homogeneously staining regions. The precise nature of these markers, i.e., exactly which regions of chromosome 19 are involved and from which chromosome(s) the additional material comes, could only rarely be established. We have investigated by high resolution array‐CGH a series of 29 chromosome 19 markers after previous microdissection of ovarian carcinoma metaphases followed by FISH to determine where in chromosome 19 the rearrangements took place as well as from which partner chromosomes the additional material stems, obtaining informative results on 23 markers from 18 carcinomas. Along the entire chromosome 19, a total of nine regions were found gained in 10 or more carcinomas (from 10 to 16) whereas 15 regions were gained in 6 to 10 markers. The most commonly gained region (16 markers) was observed in 19p13 between 20.80 Mbp and 20.85 Mbp from 19pter. According to the human genome 18 (hg18) NCBI 36, a total of 43 genes reside in the most commonly gained regions. Most of them (n = 31) code for zinc finger proteins. None of these genes is known to be involved in human neoplasia (the only exception is the ZNF91, which is found highly expressed in seminomas) but their frequent gain in the examined tumors makes all of them candidates for a pathogenetic role in ovarian carcinogenesis. © 2010 Wiley‐Liss, Inc.     

Cytogenetic and fluorescence in situ hybridization analyses of chromosome 19 aberrations in pancreatic carcinomas: Frequent loss of 19p13.3 and gain of 19q13.1-13.2

Cytogenetic investigation of nine pancreatic carcinomas revealed structural rearrangements of chromosome 19 in eight cases, resulting in a high frequency of 19p losses and 19q gains. To characterize these imbalances further, we performed fluorescence in situ hybridization (FISH) analysis with 12 mapped and evenly distributed cosmids. The FISH study not only verified the cytogenetic findings but also disclosed additional chromosome 19 aberrations not detected by chromosome banding analysis. Seven carcinomas displayed 19p losses, always including 19p13.3, either through partial- or whole-arm deletions. Six cases showed gain of 19q, usually as one to two copies above the ploidy level. In one case, a high level of amplification in 19q13.1 was seen. The commonly overrepresented segment was 19q13.1-13.2. These results suggest that genes of importance in the development of pancreatic carcinomas are located in 19p13.3 and 19q13.1-13.2. Genes Chromosomes Cancer 21:8–16, 1998. © 1998 Wiley-Liss, Inc.     

A recurrent 19q11-12 breakpoint suggested by cytogenetic and fluorescence in situ hybridization analysis of three glioblastoma cell lines

Loss of genetic material at chromosome 19 is a rather frequent finding in malignant gliomas. Loss of heterozygosity at region 19q13.3 is common in oligodendrogliomas and is also present, together with other genetic alterations on the same chomosome, in glioblastoma multiforme (GBM). Here we describe the results of cytogenetic and fluorescence in situ hybridization analysis on three GBM cell lines in which a series of complex chromosomal rearrangements affecting chromosome 19 were present. These genetic alterations suggest the presence of a common breakpoint at 19q11–12 which may point to the localization of a fragile site and/or to the presence of tumor suppressor gene(s) in the pericentromeric region of chromosome 19.     

Chromosome rearrangements at 12q13 in two cases of chondrosarcomas.

We analyzed the karyotypes of two moderately differentiated (grade 2) chondrosarcomas. Case 1 had a reciprocal translocation between chromosomes 6 and 12, t(6;12)(q25;q13) in most of the cells analyzed, as well as trisomies of chromosomes 7, 8, 11, 17, 19, and 21 and tetrasomy of chromosome 19. A reciprocal translocation involving chromosomes 12 and 19, t(12;19)(q13;q13), was noted as a highly clonal abnormality in the other case. Some cells had t(12;19) as the sole chromosome abnormality. Thus, chromosome rearrangements involving the long arm of chromosome 12 at the same region (q13) were commonly identified in the two tumors. These findings suggest that the rearrangements at 12q13 are nonrandom acquired changes that characterize a subgroup of chondrosarcomas.     

A t(2;19)(p13;p13.2) in a giant invasive cardiac lipoma from a patient with multiple lipomatosis

Cardiac lipomas occur infrequently but account for a significant portion of rare cardiac tumors. Common cutaneous lipomas have previously been associated with rearrangements of chromosome band 12q15, which often disrupt the high-mobility-group protein gene HMGIC. In this report, we describe the cytogenetic analysis of an unusual giant cardiac lipoma that exhibited myocardial invasion in a patient with a history of multiple lipomatosis (cutaneous lipoma, lipomatous gynecomastia, lipomatous hypertrophy of the interatrial septum, and dyslipidemia). Cytogenetic studies of cells derived from the cardiac lipoma demonstrated no abnormalities of chromosome 12, but did reveal a t(2;19)(p13;p13.2). A liposarcoma-derived oncogene (p115-RhoGEF) previously mapped to chromosome 19 and the low-density lipoprotein receptor gene (LDLR) previously mapped to chromosome band 19p13 were evaluated to determine whether they were disrupted by this translocation. Fluorescence in situ hybridization analyses assigned p115-RhoGEF to chromosome 19 in bands q13.2-q13.3 and mapped the LDLR to chromosome arm 19p in segment 13.2, but centromeric to the t(2;19) breakpoint. Thus, these genes are unlikely to be involved in the t(2;19)(p13;p13.2). Further studies of the regions of chromosomes 2 and 19 perturbed by the translocation in this unusual infiltrating cardiac lipoma will identify gene(s) that participate in adipocyte growth and differentiation and may provide insight into syndromes of multiple lipomatosis.