Isodicentric 7p, idic(7)(q11.2), in acute myeloid leukemia associated with older age and favorable response to induction chemotherapy: a new clinical entity?

Three adult de novo acute myeloid leukemias (AML M1, M2, and M4) with an isochromosome 7p are presented. No additional abnormalities were detected by G-band and multicolor, using combined binary ratio labeling, fluorescence in situ hybridization (FISH) analyses, indicating that the i(7p) was the sole, i.e., the primary, chromosomal aberration. Although the patients were elderly--68, 72, and 78 years old--they all responded very well to chemotherapy, achieving complete remission lasting more than a year. Further FISH analyses, using painting, centromeric, as well as 7q11.2-specific YAC probes, revealed that the i(7p) contained two centromeres and that the breakpoints were located in 7q11.2. Thus, the abnormality should formally be designated idic(7)(q11.2). The detailed mapping disclosed a breakpoint heterogeneity, with the breaks in 7q11.2 varying among the cases, being at least 1,310 kb apart. Furthermore, the breakpoints also differed within one of the cases, being located on both the proximal and the distal side of the most centromeric probe used. Based on our three patients, as well as on a previously reported 82-year-old patient with AML M2 and idic(7)(q11) as the only chromosomal change, we suggest that this abnormality, as the sole anomaly, is associated with AML in elderly patients who display a good response to induction chemotherapy and, hence, have a favorable prognosis. Furthermore, the heterogeneous breakpoints in 7q11.2 suggest that the important functional outcome of the idic(7)(q11.2) is the genomic imbalance incurred, i.e., gain of 7p and loss of 7q material, rather than a rearrangement of a specific gene.

Unbalanced chromosomal rearrangements in a metastasizing salivary gland tumor with benign histology.

Benign metastasizing pleomorphic adenoma (BMPA) is a rare tumor of the salivary glands. Despite benign histopathologic features, it can metastasize and is sometimes lethal. No chromosomal data have been reported for this tumor type. We have by chromosome banding and fluorescence in situ hybridization analysis examined the short-term cultures of three skeletal metastases from a BMPA and identified two related hypodiploid clones: 44,XX,dic(3;22)(p11;q13) or der(3)t(3;22)(p11;q?) add(22)(q?),der(9;21)(q10;q10),der(13)t(1;13)(q11;p13)/45,XX,-3,der(9;21 ) (q10;q10),der(13)t(1;13)(q11; p13),?der(22)t(3;22)(q22;q13), +mar. The karyotypic features of this BMPA thus differ from the characteristic cytogenetic findings in pleomorphic adenomas and carcinomas ex pleomorphic adenoma.

Genomic amplification of CCND2 is rare in non-Hodgkin lymphomas.

Cyclin D2, encoded by CCND2 at 12p13, takes part in the regulation of the cell cycle and has been suggested as a candidate for gene amplification in lymphoid malignancies. CCND2 is often overexpressed in chronic B-cell disorders, and we recently detected genomic amplification of the chromosomal region containing CCND2 in two of three investigated non-Hodgkin lymphomas (NHLs) with cytogenetic abnormalities involving 12p. In the present study, 58 NHLs without karyotypic evidence of 12p aberrations were analyzed by fluorescence in situ hybridization with probes for CCND2. No genomic amplification was found, strongly suggesting that this abnormality is rare in such NHLs.

Deletions of CDKN1B and ETV6 in acute myeloid leukemia and myelodysplastic syndromes without cytogenetic evidence of 12p abnormalities.

Seventy-nine acute myeloid leukemias (AML) and myelodysplastic syndromes without cytogenetic evidence of 12p aberrations were investigated by fluorescence in situ hybridization with probes for ETV6 and CDKN1B (previously called TEL and KIP1, respectively) to ascertain whether abnormalities of these genes are frequently undetected by standard chromosome banding analyses and, if so, whether they are associated with specific karyotypic patterns and morphologic features. One of sixty cytogenetically aberrant myeloid malignancies, an AML with a complex karyotype including del(5q) and del(20q), showed a hemizygous interstitial deletion of the ETV6 and CDKN1B loci. No concomitant rearrangement of the other ETV6 allele was detected. Two of nineteen cytogenetically normal AML displayed a hemizygous interstitial deletion involving CDKN1B, but not ETV6. Thus, cryptic deletions of these genes seem to be rare in cytogenetically abnormal myeloid malignancies without 12p aberrations (2%), whereas they may be more frequent in karyotypically normal AML (10%). Furthermore, the present findings show that the deletions may be narrow, not including the ETV6 gene, and indirectly suggest that CDKN1B, or a closely located genomic segment, is the target of 12p deletions.

Fluorescence in situ hybridization analysis of whole-arm 7;12 translocations in hematologic malignancies.

Cytogenetic analysis of one case of acute myeloid leukemia (AML), one of acute lymphoblastic leukemia (ALL), one of refractory anemia with excess of blasts (RAEB), and one of acute mixed lineage leukemia (AMLL) with unbalanced 7;12 translocations mapped the breakpoints to the centromeres on both chromosomes. The rearrangements were interpreted as the whole-arm translocations der(7;12)(q10;q10) in the AML and ALL and der(7;12)(p10;q10) in the RAEB and AMLL. However, further analysis by metaphase and/or interphase fluorescence in situ hybridization (FISH) showed centric fusion only in the AML and ALL. In the RAEB and AMLL, centromeric material from chromosome 7 but not from 12 was present in the derivative chromosome. Whereas the t(7;12) resulted in loss of 12p in all four cases, the corresponding chromosome 7 imbalances differed--monosomy for 7q in the RAEB and AMLL and monosomy for 7p in the AML and ALL. Six hematologic neoplasms with unbalanced whole-arm or near-centromeric 7;12 translocations and seven dic(7;12) with juxtacentromeric breakpoints have been reported previously: 2 AML, 1 RAEB in transformation, and 10 ALL. All karyotypically informative cases had loss of 12p material. All but one of the cases with combined 7p and 12p deletion were ALL, whereas all cases with 7q and 12p loss showed myeloid differentiation. No particular clinical, morphologic, or immunophenotypic features seem to characterize ALLs with t(7;12). AMLs with an unbalanced t(7;12), often together with 5q deletions, might be associated with previous genotoxic exposure and poor prognosis.

Karyotypic features of malignant tumors of the nasal cavity and paranasal sinuses.

Cytogenetic analysis of short-term cultures from 6 tumors of the nasal cavity and paranasal sinuses--one esthesioneuroblastoma, 2 adenocarcinomas and 3 squamous-cell carcinomas (SCC)--revealed clonal chromosome aberrations in all cases. The esthesioneuroblastoma had a complex hyperdiploid karyotype. None of the aberrations was similar to those previously described in short-term cultures or established cell lines from esthesioneuroblastomas. The 2 adenocarcinomas had complex karyotypic changes, which in both cases included rearrangements of bands 9p22 and 14q11. One SCC had 5 unrelated pseudodiploid clones, 1 displayed a highly complex karyotype, including rearrangement of band 11q13, and 1 had simple karyotypic changes with loss of 6q material and gain of 3q. These findings are similar to those described in head-and-neck SCC at other sites.

Rearrangement of the transcription factor gene CHOP in myxoid liposarcomas with t(12;16)(q13;p11).

Most myxoid liposarcomas (MLS) are characterized cytogenetically by a t(12;16)(q13;p11). It is reasonable to assume that this translocation corresponds to the consistent rearrangement of one or two genes in 12q13 and/or 16p11, and that the loci thus affected are important in the normal control of fat cell differentiation and proliferation. We have used Southern blot technique to test whether a gene of the CCAAT/enhancer binding protein (C/EBP) family, CHOP, which maps to 12q13 and is assumed to be involved in adipocyte differentiation, could be the 12q gene in question. Using a cDNA probe that spans the CHOP coding region, we detected one rearranged and one wild type allele in nine of nine MLS with t(12;16). Using PCR generated, site-specific probes corresponding to the non-coding exons 1 and 2 and intron 2 of CHOP, rearrangements in five of seven tumors mapped to the 2.4 and 1.6 kbp PstI fragments that contain the first two exons and introns of the gene and the upstream promoter region. In contrast to the findings in MLS, no tumor without a t(12;16) exhibited aberrant CHOP restriction digest patterns. These tumors included one highly differentiated liposarcoma with abnormal karyotype but no involvement of 12q13, seven lipomas with various cytogenetic aberrations of 12q13-15, two uterine leiomyomas with t(12;14) (q14-15;q23-24), and one hemangiopericytoma and one chondroma, both of which also had 12q13 changes.(ABSTRACT TRUNCATED AT 250 WORDS)

Pseudohypoparathyroidism type I and Albright's hereditary osteodystrophy with a proximal 15q chromosomal deletion in mother and daughter.

A 33-year-old woman and her 71-year-old mother were both found to have pseudohypoparathyroidism type I with Albright's hereditary osteodystrophy associated with a cytogenetic deletion of the proximal part of one chromosome 15, resembling that found in Prader-Willi syndrome. As there are overlapping clinical features between these two syndromes a causal relationship cannot be excluded. However, molecular analyses with 10 probes from this region did not detect any uniparental disomy or deletion, features frequently found in Prader-Willi syndrome.

Involvement of 3p deletions in sporadic and hereditary forms of renal cell carcinoma.

Deletions of the short arm of chromosome 3 and associated allele losses have been reported in the majority of sporadic renal cell carcinomas (RCC). On the basis of the combined cytogenetic and molecular data, it is reasonable to assume that a putative RCC locus, which contributes to tumor development by its loss, is located telomerically of the D3F15S2 site. Using H3E4, a D3F15S2-specific probe, we have isolated a cDNA clone (cl.4-2), and a sequence comparison revealed that the cDNA clone corresponds to the human acyl-peptide hydrolase gene. The gene is fairly universally expressed, but in RCC biopsies its expression is severely reduced, compared to the normal kidney. Cl.4-2 was used for in situ hybridization on metaphase chromosomes prepared from an Epstein-Barr virus (EBV) transformed lymphoblastoid cell line, derived from a t(3;8) (p14.2;q24.1) carrying member of the RCC family described by Cohen et al. in 1979 (N Engl J Med: 301:592-595). Carriers of this translocation regularly develop RCC by middle age. We now report that D3F15S2 is localized on the telomeric side of the constitutional breakpoint, in 3p21. The region of 3p affected by this familial translocation is thus not identical with the region of 3p most frequently deleted in sporadic RCC.

GLI3 encodes a 190-kilodalton protein with multiple regions of GLI similarity.

The GLI oncogene, discovered by virtue of its amplification in human tumors, encodes a sequence-specific DNA-binding protein containing five zinc fingers. We have now characterized one member of a family of GLI-related zinc finger genes. A previously identified fragment of GLI3 genomic DNA was used to localize GLI3 to chromosome 7p13 and to isolate cDNA clones. Sequence analysis of these clones and identification of the GLI3 protein by using polyclonal antisera demonstrated that GLI3 encodes a protein of 1,596 amino acids and an apparent molecular mass of 190 kilodaltons. Amino acid sequence comparison with GLI demonstrated seven regions of similarity (53 to 88% identity), with the zinc fingers representing the most similar region. Furthermore, when produced in vitro, the GLI3 protein bound specifically to genomic DNA fragments containing GLI-binding sites. Amino acid sequence comparison with the product of another member of the GLI family, the Drosophila segment polarity gene cubitus interruptus Dominant, revealed additional similarity that was not shared with GLI. These studies suggest that the GLI-related genes encode a family of DNA-binding proteins with related target sequence specificities. In addition, sequence similarity aside from the zinc finger region suggests that other aspects of function are shared among the members of this gene family.

Chromosomal rearrangements in chondromatous tumors.

Short-term cultures from 16 chondromatous tumors, 15 primary and one recurrent, were analyzed cytogenetically. Clonal chromosome aberrations were found in one of six benign tumors and in seven of ten malignant tumors. A chondroma had a complex translocation involving chromosomes X, 8, 12, and 13, as well as a deletion of the derivative chromosome 8. In the malignant tumors, monosomy 6 and 22 were observed in three tumors and monosomy 10, 11, 13, and 18 were observed in two tumors. In two of the three metastasizing tumors, del(5) (q13) and loss of chromosomes 6, 10, 11, 13, and 22 were common features. Structural aberrations of chromosome 1 were found in five tumors, of chromosomes 6, 12, and 15 in three tumors, and of chromosomes 4, 5, 9, and 20 in two tumors. We conclude that although considerable cytogenetic heterogeneity exists among chondromatous tumors, the karyotypic anomalies are still nonrandom.

The INT1 oncogene is not rearranged or amplified in lipomas with structural chromosomal abnormalities of 12q13-15.

DNA from nine different solitary subcutaneous lipomas, all with clonal abnormalities affecting the chromosome segment 12q13-15, was examined for rearrangement or amplification of a human INT1 gene sequence. INT1 is a putative oncogene that has been localized to the chromosome band 12q13. No rearrangement or amplification could be detected.

The gene for the human putative apoE receptor is on chromosome 12 in the segment q13-14.

We have previously described the cDNA coding for a new lipoprotein receptor that contains domains closely related to the ligand-binding domain of the LDL receptor. We have now investigated the localization of the gene for this new receptor by hybridization of the cDNA to panels of rodent cells containing subsets of human chromosomes and by in situ hybridization of the cDNA to chromosomes. The gene maps to 12q13-14, a known hot spot for chromosomal rearrangements in human neoplasia. Of particular interest is the frequent involvement of the 12q13-14 segment in clonal abnormalities in lipomas and myxoid liposarcomas, and it is possible that LRP may play a role in the pathogenesis of such tumors.

No amplification or rearrangement of INT1, GLI, or COL2A1 in uterine leiomyomas with t(12;14)(q14-15;q23-24).

We have studied three uterine leiomyoma tumors, all previously cytogenetically analyzed and shown to have the clonal abnormality t(12:14)(q14-15;q23-24), with the purpose of detecting amplification or rearrangement of three genes that are localized close to the 12q breakpoint region. The genes studied were the two putative oncogenes INT1 and GLI, and the collagen type II alpha 1 gene, COL2A1. No rearrangement or amplification could be detected for any of the three gene sequences.

In situ hybridization localizes the human putative oncogene GLI to chromosome subbands 12q13.3-14.1.

Using in situ hybridization, we have localized the human putative oncogene GLI to chromosome subbands 12q13.3-14.1. The precise genomic site is of interest since the region 12q13-15 has been found to be consistently rearranged in neoplasia-associated chromosome abnormalities in lipomas, myxoid liposarcomas, uterine leiomyomas, and pleomorphic adenomas of the salivary gland.

In situ hybridization localizes the human type II alpha 1 collagen gene (COL2A1) to 12q13.

We have, using in situ hybridization technique, localized the human type II alpha 1 collagen gene (COL2A1) to chromosome band 12q13. The gene had previously been assigned to either 12q13.1-13.2 or 12q14.3. Since the chromosome segment 12q13-15 has been shown to be rearranged in several benign and malignant human neoplasms, the exact band localization of COL2A1 within this region makes it a useful marker for the molecular analysis of these tumors.

Localization in man of fifteen DNA sequences within the chromosome segment 13q12-q22.

Fifteen human chromosome 13 specific DNA fragments, isolated from a lambda phage genomic library, were localized within the segment 13q12-q22. One was mapped to 13q12.1-q12.2, three to 13q12.3-q13.1, one to 13q14,1-q14.2, five to 13q14.1-q21.1, one to 13q21.1-q21.2, two to 13q21.2, and one to 13q22.1, and one to 13q22. The localization was performed by hybridization to Southern blots of a panel of human cell lines with overlapping deletions in 13q, and for three probes also by in situ hybridization to metaphase chromosomes.