Additional Trisomies Research Articles

22. Masked hypodiploid B-Cell Lymphoblastic Leukemia (B-ALL) characterized by SNP microarray in a Li Fraumeni syndrome patient with post therapy karyotype changes

Cases of B-ALL with chromosome counts of >60 and tetrasomic for chromosomes 6, 18, 21 and X are suspicious for “masked hypodiploidy” in that the theoretic hypodiploid stemline is present as a doubled clone only. To characterize and define these cases when FISH and chromosomes show no evidence of the hypodiploid clone, our laboratory utilizes the IlluminaⓇ Cyto-SNP 850K microarray to recognize the loss of heterozygosity (LOH) of the disomic chromosomes. We report an 18yo female with a known diagnosis of Li Fraumeni syndrome, referred to Cytogenetics with pancytopenia and circulating blasts. Cytogenetic results at diagnosis revealed three hyperdiploid clones with counts of 62-64, tetrasomy for X, 1, 6, 18, and 21, with additional trisomies and structural rearrangements including a derivative 17p with 11q. No evidence for monosomy was observed by FISH or chromosomes. Microarray results confirmed loss of heterozygosity (LOH) for those chromosomes present in 2 copies. Genes associated with low hypodiploid B-ALL include TP53, IKZF1 and RB1 which were present in 2 copies on the isodisomic chromosomes in this specimen. This patient was in remission for several months, but with reemergence of B-ALL, underwent CD19 directed CAR-T therapy which resulted in deep remission (by NGS-MRD). Recent surveillance studies showed a karyotype change to loss of 5q and TP53 by FISH and a dic(5;17)(q11.2;p11.2) consistent with MDS. Microarray studies confirm the MDS genetic findings and were negative for the masked hypodiploid findings present at diagnosis. This strategy has been useful to report chromosome results with confidence for cases of masked hypodiploidy that may have been otherwise misinterpreted.

Cost‐effectiveness of five prenatal screening strategies for trisomies and other unbalanced chromosomal abnormalities: model‐based analysis

To evaluate the cost-effectiveness of five prenatal screening strategies for trisomies (13/18/21) and other unbalanced chromosomal abnormalities (UBCA), following the introduction of cell-free DNA (cfDNA) analysis. A model-based cost-effectiveness analysis was performed to estimate prevalence, safety, screening-program costs and healthcare costs of five different prenatal screening strategies, using a virtual cohort of 652 653 pregnant women in France. Data were derived from the French Biomedicine Agency and published articles. Uncertainty was addressed using one-way sensitivity analysis. The five strategies compared were: (i) cfDNA testing for women with a risk following first-trimester screening of ≥ 1/250; (ii) cfDNA testing for women with a risk of ≥ 1/1000 (currently recommended); (iii) cfDNA testing in the general population (regardless of risk); (iv) invasive testing for women with a risk of ≥ 1/250 (historical strategy); and (v) invasive testing for women with a risk of ≥ 1/1000. In our virtual population, at similar risk thresholds, cfDNA testing compared with invasive testing was cheaper but less effective. Compared with the historical strategy, cfDNA testing at the ≥ 1/1000 risk threshold was a more expensive strategy that detected 158 additional trisomies, but also 175 fewer other UBCA. Implementation of cfDNA testing in the general population would give an incremental cost-effectiveness ratio of €9 166 689 per additional anomaly detected compared with the historical strategy. Extending cfDNA to lower risk thresholds or even to all pregnancies would detect more trisomies, but at greater expense and with lower detection rate of other UBCA, compared with the historical strategy. Copyright © 2019 ISUOG. Published by John Wiley & Sons Ltd.

Mutational and cytogenetic analyses of 188 CLL patients with trisomy 12: A retrospective study from the French Innovative Leukemia Organization (FILO) working group.

Trisomy 12 (tri12) is the second most frequent chromosomal aberration (15%-20%) in chronic lymphocytic leukemia (CLL). Tri12 confers an intermediate prognosis but is a heterogeneous entity. We examined whether additional mutational or chromosomal alterations might impact tri12 patient outcomes. This retrospective study, carried out by the French Innovative Leukemia Organization, included 188 tri12 patients with comprehensive information on immunoglobulin heavy chain (IGHV) gene status, karyotypic/FISH abnormalities, and NOTCH1, TP53, SF3B1, and MYD88 mutations. The main cytogenetic abnormalities associated with tri12 were del(13q) (25%), additional trisomies (14%) (including tri19 (10%) and tri18 (4%)), 14q32 translocations (10%), del(17p) (6.5%), del(14q) (4%), and del(11q) (4%). Unmutated (UM) IGHV, NOTCH1, and TP53, mutations were identified in respectively 66%, 25%, and 8.5% of cases. Multivariate analyses showed that additional trisomies (HR = 0.43, 95% CI = 0.23-0.78, P = .01) were associated with a significantly longer time to first treatment in Binet stage A patients and with a lower risk of relapse (HR = 0.37, 95% CI = 0.15-0.9, P = .03) in the overall tri12 population. Binet stage B/C, TP53 disruption, and UM IGHV status were associated with a shorter time to next treatment, while Binet stage B/C (HR = 4, 95% CI = 1.6-4.9, P = .002) and TP53 disruption (HR = 5, 95% CI = 1.94-12.66, P = .001) conferred shorter overall survival in multivariate comparisons. These data indicate that additional cytogenetic and mutational abnormalities, and particularly additional trisomies, IGHV status, and TP53 disruption, influence tri12 patient outcomes and could improve risk stratification in this population.

Occurrence and Prognostic Significance of Cytogenetic Evolution in Patients with Multiple Myeloma

Abstract Background: Cytogenetic evaluation, especially using fluorescence in situ hybridization (FISH), at the time of diagnosis is essential for initial risk stratification and the employment of risk-adapted treatment strategies in multiple myeloma. Little is known about the occurrence and prognostic significance of cytogenetic evolution during follow up. Methods: We studied 433 patients who were diagnosed with multiple myeloma between January 2000 and December 2011 and had at least two FISH evaluations at Mayo Clinic Rochester, including the diagnostic specimen. Bone marrow aspirates were evaluated for deletions, monosomies, trisomies, and tetrasomies using chromosome- or centromere-specific FISH probes. IGH rearrangements were evaluated using an IGH break-apart probe and up to five potential partners (FGFR3, CCND1, CCND3, MAF, and MAFB). Cytogenetic evolution was defined as a new deletion, monosomy, trisomy, tetrasomy, or translocation during follow up. Multivariable-adjusted logistic regression models were used to assess the associations between the parameters of interest and the presence of cytogenetic evolution in follow-up specimens. Multivariable-adjusted Cox proportional hazards models were used to assess the effect of cytogenetic evolution on overall survival. All models were adjusted for sex, age, the presence of high-risk FISH abnormalities, and the number of abnormalities at the time of diagnosis. Likelihood ratio tests were used to assess the goodness of fit of nested models. The χ2 or Fisher's exact test was used to assess the distribution of cytogenetic abnormalities in subgroups. Results: The median age at diagnosis was 60 years (32 - 82), 264 (61%) of the patients were male. The median overall survival for the entire cohort was 7.0 years (6.2 - 7.8). At the time of diagnosis, 150 (35%) and 57 (13%) of the 433 patients presented with a hyperdiploid karyotype and cytogenetic high-risk abnormalities, respectively. Independent of each other, the presence of a translocation at the time of diagnosis was associated with decreased odds of cytogenetic evolution during follow up (OR 0.39, 95% CI 0.24 - 0.63, p < 0.001) while the presence of at least one trisomy or tetrasomy at the time of diagnosis was associated with increased odds (OR 2.53, 95% CI 1.37 - 4.70, p = 0.003). A greater proportion of patients presenting with a hyperdiploid karyotype experienced cytogenetic evolution during follow up. Those patients more frequently evolved additional trisomies and tetrasomies, while translocations were more common in those presenting with a non-hyperdiploid karyotype (Table 1). The development of additional abnormalities during the three years following diagnosis (compared to no new abnormalities) was associated with increased subsequent mortality in those who survived at least three years (HR 3.22, 95% CI 1.82 - 5.68, p < 0.001). Including the time between first and last cytogenetic evaluation as a covariate did not significantly change the parameter estimates or improve model fit (p = 0.727). Conclusions: Demographics, risk profile, and overall survival of this cohort reflect the fact that patients had to survive long enough to undergo repeated cytogenetic evaluation. Hyperdiploid and non-hyperdiploid genotypes were associated with distinct behavior regarding cytogenetic evolution during follow up. The identification of cytogenetic evolution was an adverse prognostic factor in those who survived at least three years after diagnosis. These findings emphasize the importance of the dynamics of the underlying clonal disease process for accurate risk assessment and suggest that selected subgroups of patients may benefit from risk stratification during follow up. Table 1. Cytogenetic evolution during follow up in 433 patients with multiple myeloma stratified by karyotype at the time of diagnosis Hyperdiploid (n = 150) Non-hyperdiploid (n = 283) p New abnormality 76 (51%) 108 (38%) 0.012 New monosomy 8 (5%) 24 (8%) 0.243 New trisomy 48 (32%) 55 (19%) 0.004 New tetrasomy 37 (25%) 27 (10%) < 0.001 New deletion 17 (11%) 27 (10%) 0.557 New translocation 1 (1%) 11 (4%) 0.065 Most common new abnormality [type (percent of type in each group)] Monosomy mono(13) (75%) mono(13) (62%) Trisomy tri(11) (22%) tri(3) (22%) Tetrasomy tetra(15) (48%) tetra(15) (30%) Deletion del(17p) (79%) del(17p) (63%) Translocation t(11;14) (100%) t(11;14) (36%) Data are given as count (percent) unless denoted otherwise. Disclosures Binder: American Society of Hematology: Research Funding. Kumar:AbbVie: Research Funding; Onyx: Research Funding; Sanofi: Research Funding; Celgene, Millenium, Sanofi, Skyline, BMS, Onyx, Noxxon,: Other: Consultant, no compensation,; Skyline, Noxxon: Honoraria; Millenium/Takeda: Research Funding; Janssen: Research Funding; Celgene: Research Funding.

Obstetrician and Gynecologist Utilization of the Noninvasive Prenatal Testing Expanded Option

Objective Noninvasive prenatal testing (NIPT) enables the detection of common fetal aneuploidies such as trisomy 21, trisomy 18, trisomy 13, and sex chromosome abnormalities via analysis of cell-free fetal DNA circulating in maternal serum. In October 2013, the option to screen for additional trisomies and select microdeletion syndromes became clinically available. The complex testing methods, oftentimes unclear clinical utility of results, and lack of professional guidelines renders it challenging for clinicians to keep abreast of evolving prenatal screening options. We undertook a survey to assess physicians' awareness of, utilization of, and attitudes toward the expanded NIPT option. Study Design Obstetricians attending hospital service meetings in the Houston Texas Medical Center completed an anonymous survey regarding the utilization patterns of expanded NIPT. Results Overall, 85 obstetricians were surveyed. While all respondents indicated awareness of NIPT in its traditional form, 75% (64/85) were aware of the expanded testing option, and 14% (12/85) reported having ordered the expanded NIPT option. A total of 91% (77/85) expressed that practitioners need more information regarding the screening. Conclusion Based on these findings and the fluid landscape of prenatal screening, education, and reeducation of health care professionals is imperative to ensure responsible patient counseling, informed consent, and appropriate posttest management.

Sequential SNP6.0 Microarray Analysis In Rai Stage 0 CLL Patients with Either Stable or Progressive Identifies Genomic Evolution In Both Cohorts

AbstractAbstract 1696Sequential karyotypic and/or FISH analysis in patients with CLL show evidence of genomic evolution in 10 – 20% of cases. Common secondary abnormalities include loss of the second allele of 13q14, additional trisomies or translocations involving the immunoglobulin gene loci in patients with trisomy 12 and complex karyotypic abnormalities in patients with loss and/or mutation of the p53 and ATM genes. However the clinical significance of genomic evolution in patients presenting with early stage disease remains uncertain. Nor is it clear whether the use of high resolution genomic arrays can detect additional clinically relevant abnormalities in this cohort of patients. To address these issues we performed sequential genomic studies using the affymetrix SNP 6.0 platform (Affymetrix, Santa Clara, CA), G-banding and FISH in 29 patients presenting with either stage A0 CLL or MBL in whom IGVH gene mutational status and CD38 and ZAP 70 expression were known. In each case, Partek Genomic Suite (Partek Incorporated, St Louis, MS) was used to identify acquired copy number alterations (CNAs) and copy number neutral LOH events (CNNLOH) by comparing the disease presentation (PT) and subsequent (FU) SNP tumor profiles to each other and to matched germ-line DNA extracted from buccal cells. Patients were subdivided into those that subsequently exhibited stable disease for a minimum of 5 years (n=9) with a median time between sampling of 8 years (range 2 – 15) or those that developed progressive disease (n=20) with a median time between sampling of 4 years (range 1 – 10). 8 patients with progressive disease were treated prior to the follow up sample. All stable cases and 13/20 with progressive disease had mutated IGHV genes. The concordance between G-banding, FISH and SNP array data was >99%. In each case, a more complex genome was present at FU. The acquisition of additional CNAs was not associated with IgVH mutation status, ZAP-70, CD38 positivity or whether a patient had been treated. When these data were stratified for whether a patient subsequently exhibited stable or progressive disease, the following observations were made. Firstly, there was no difference in the acquisition of small CNAs (<1Mb) between stable or progressive patients. However, the mean number of additional large CNAs (>1Mb) per patient and the total genomic size of these additional changes were greater in progressive cases; stable and progressive cases exhibited a mean of 0.67 and 1.1 additional CNAs at FU and a mean total imbalance of 2.33Mb and 16.9Mb, respectively. In this limited series these differences did not reach statistical significance. Interestingly, the frequency of copy number variations (CNV, annotated in the Database of Genomic Variation; http://projects.tcag.ca/variation/) was higher in cases that went on to develop progressive disease (P=0.002). The size of established recurrent CNAs also changed between time-points. Most notably, several cases exhibited larger 13q14 deletions at FU. Two patients with deletion or CNNLOH of 17p displayed a more complex genome at FU, characterized by multiple CNAs larger than 1Mb. One patient acquired CNNLOH on 17p at FU in addition to five additional CNAs (>1Mb). Conversely, the degree of complexity did not increase in a patient with an ATM deletion. Six cases without an apparent abnormality of ATM or TP53 showed complex genomes at PT and additional CNAs (mean 2.8) at FU. A series of novel, recurrent CNAs were observed exclusively in FU samples, including duplications of 13q and 15q observed in 38% and 53% of patients, respectively. In conclusion, using high resolution microarray analysis we show genomic evolution in early stage patients with predominantly good risk biomarkers who pursued either an indolent or progressive course. However, our data suggests that larger acquired CNAs may be more prognostically relevant than smaller regions. We show preliminary data implicating CNVs in the pathogenesis of CLL and we have also identified a series of novel acquired regions of CNAs that may harbor cancer genes which it is hoped will contribute to our understanding of the pathophysiology of CLL and/or have clinical relevance. Disclosures:No relevant conflicts of interest to declare.

Three genetic developmental stages of papillary renal cell tumors: Duplication of chromosome 1q marks fatal progression

Papillary renal cell tumors (RCT) make up a cytomorphologically and biologically heterogeneous group of kidney cancers including renal cell adenomas (RCA) and renal cell carcinomas (RCC). To find genetic markers landmarking the tumor progression, we have evaluated the genetic alterations obtained by karyotyping, chromosomal and array-CGH and compared with the cytological characteristics and biological behavior of 60 papillary RCTs. Based on the genetic and clinical data, we have separated 3 groups of tumors and proposed 3 genetically defined developmental stages of papillary RCTs. Papillary RCAs are characterized by combined trisomy of chromosomes 7 and 17, whereas papillary RCCs displayed additional trisomies of 3q, 8q, 12q, 16q and 20q. In addition to the genetic changes occurring in the second group, the third group of tumors was characterized by 1q gain and 6q, 8p, 9p and 14q losses. Kaplan-Meier analysis revealed a significant association between chromosome 1q gain and deadly outcome of the disease. The cytomorphological variation and size of tumors in the second and third groups did not correlate with the clinical outcome. Therefore, we suggest that our genetic classification system landmarking papillary RCA, papillary RCC without and with progression offer a better system to characterize the tumor biology of clinical significance than a cellular/morphological classification.

Familial myelodysplastic syndromes, monosomy 7/trisomy 8, and mutator effects

A family is reported, in which two sisters presented with myelodysplastic syndrome (MDS), namely refractory anemia with excess of blasts in transformation (RAEB-t), and refractory anemia (RA). Bone marrow chromosome changes were present in both: trisomy and tetrasomy 8 (with a pericentric inversion of one chromosome 8) in the older sister, and monosomy 7 (with clones with additional trisomies 19 and 21) in the younger one. Molecular data were obtained on the parental chromosome involved in these numerical anomalies, which proved to be of paternal origin in these cases. The observations of this family, and a review of familial cases of MDS/acute myeloid leukemia (AML), led us to consider that they may be divided into two groups: those which arise on the basis of a Mendelian predisposing disorder exerting a mutator effect, often with the acquisition of monosomy 7, and those in which no specific Mendelian predisposing disease is recognized, as the familial monosomy 7 cases and the one reported here. We postulate that in these families an inherited mutator effect is present and that it causes a karyotype instability, which leads to MDS/AML, often through the acquisition of monosomy 7 and trisomy 8.

Numerical chromosomal aberrations in papillary renal cortical tumors: relationship with histopathologic features.

Previous studies have indicated that a combined trisomy of chromosomes 7 and 17 is a constant finding in papillary renal cortical adenomas and that papillary renal cell carcinomas are marked by additional trisomies such as trisomy 12, 16, and 20. The aim of our study was to compare this cytogenetic classification of papillary renal cortical tumors with conventional histopathologic classification. We performed interphase cytogenetics with enumeration probes for chromosomes 7, 12, 16, 17, and 20 on 41 papillary tumors found in 21 nephrectomy and 10 autopsy kidneys. A total of 38 tumors harbored gains of chromosomes 7 or 17, and most of these showed a trisomic signal distribution. The three tumors with normal copy numbers for chromosomes 7 and 17 were a papillary grade-2 carcinoma, a small adenoma (both with distinctive oxyphilic cytoplasm), and a papillary carcinoma with focally clear cells. Gains for chromosomes 12, 16, or 20 were found in 21 tumors and were significantly associated with the presence of histologic criteria of malignancy ( P<0.0001). Histopathologic and cytogenetic features of malignancy were found in eight tumors smaller than 10 mm. There is a good agreement of cytogenetic and histopathologic criteria of malignancy in papillary renal cell tumors. Interphase cytogenetics might give useful additional information in cases of doubt or when only small biopsy specimens are available.

Precancerous Lesions in the Kidney

Renal cell carcinoma (RCC), although occurring less frequently than prostate and bladder cancer, is actually the most malignant urologic disease, killing >35% of affected patients. Therefore, investigation of the nature of premalignant lesions of the kidney is a relevant issue. Following the most recent histological classification RCC can be subdivided into four categories: conventional RCC; papillary RCC; chromophobe RCC; and collecting duct carcinoma. In contrast to many genitourinary malignancies, premalignant alterations in the kidney are scarcely described. Intratubular epithelial dysplasia has been recognized as the most common precursor of RCC. In analogy to prostatic intraepithelial neoplasia (PIN), the premalignant lesions of the kidney are described as high or low-grade renal intratubular neoplasia. In contrast, precancerous lesions have been described as part of the von Hippel-Lindau syndrome (VHL) where the evolution from a simple cyst to an atypical cyst with epithelial hyperplasia to cystic or solid conventional-type RCC is well documented. Finally, in the genesis of papillary RCC an adenoma-carcinoma sequence has been recognized with specific genetic changes. There are no data on the epidemiology of premalignant lesions of the kidney, but research into the etiology of RCC has been extended substantially. Familial and genetic factors are well documented in VHL disease, in hereditary papillary RCC, in the tuberous sclerosis complex and in familial RCC. Cigarette smoking and obesity are established risk factors for RCC. Hypertension or its medication has also been associated with an increased risk. Among dietary factors an inverse relation between risk and consumption of vegetables and fruit has been found. Occupational exposure to substances such as asbestos and solvents has been linked to an increased risk of RCC. Specific RCC variants have distinctive chromosome alterations and several genes have been implicated in the development of RCC. Loss of material from the 3p chromosome characterizes conventional RCC and the deletion of the VHL suppressor gene plays an important role in the genesis of this RCC variant. In contrast, numerical changes with trisomy of chromosomes 7 and 17 and loss of the sex chromosome are typical changes in papillary tumors, whereas papillary RCC have additional trisomies. Chromophobe RCC is characterized by loss of chromosomes with a combination of monosomies. Less consistent genetic alterations are associated with collecting duct carcinoma. The traditional treatment of RCC is surgery by radical or partial nephrectomy. The latter approach carries a risk of tumor recurrence as a result of unrecognized satellite lesions or premalignant lesions that might have been present at the time of surgery. However, the reported recurrence rates after partial nephrectomy are <1% and therefore the possible presence of premalignant disease does not alter the actual treatment strategy advocated. Although multifocality and bilateral occurrence of RCC are much more likely in cases of papillary RCC, biopsy of the renal remnant or contralateral kidney is not justified even in patients with this tumor type. Conversely, patients with RIN in a partial or radical nephrectomy specimen or in a renal biopsy taken for whatever reason should be subjected to closer follow-up with regularly repeated ultrasound. When an effective chemopreventive regimen becomes available it might be useful for patients with an inherited risk of RCC as well as in those who are at risk of tumor recurrence after intervention. Mass screening with the purpose of detecting RCC at its earliest stage is not recommended at the present time, but screening focused on certain risk groups can be advocated. Further research is needed to identify avoidable risks, develop effective chemoprevention and recognize patients at risk.

Cytogenetic investigations of 340 thyroid hyperplasias and adenomas revealing correlations between cytogenetic findings and histology

Cytogenetic analyses were performed on 340 follicular thyroid adenomas and goiters after short-term culture. Clonal chromosomal changes were found in 67 cases. Trisomy 7 as the sole abnormality or along with other trisomies was the most frequent type of aberration (19 cases). Other recurrent numerical changes were loss of chromosome 22 (4 cases) and the second X or the Y chromosome (5 cases). Translocations involving l9q13 (12 cases) were frequent structural chromosomal changes. Dicentric chromosomes or telomeric associations were frequent in goiters (12 cases). After a histopothologic classification of all cases, we have correlated the cytogenetic findings with the histology of the tumors. Only 8.4% of the goiters showed clonal abnormalities, whereas 44.9% of the adenomas revealed clonal abnormalities. Furthermore, simple clonal changes were predominantly found in goiters and complex changes in adenomas. The most impressive correlation was found in the group of lesions with trisomy 7. Although all but one lesion with one or two additional trisomies were goiters, those having three or more additional trisomies were all adenomas or adenomatous goiters.

The value of molecular genetic analysis in the diagnosis and prognosis of renal cell tumours.

Renal cell tumours have a heterogeneous morphology, which may also be changed during tumour progression. Through the use of molecular cytogenetic techniques, it has become possible to divide renal cell tumours into genetically well-defined entities. Papillary renal cell tumours are characterized by loss of the Y chromosome and trisomy of chromosomes 3q, 7, 8, 12, 16, 17 and 20. Non-papillary renal cell carcinomas show a specific loss of chromosome 3p and trisomy of chromosome 5q sequences and frequent loss of chromosome 6q, 8p, 9 and 14q sequences. Chromophobe renal cell carcinomas are marked by a highly specific combination of loss of chromosomes 1, 2, 6, 10, 13, 17 and 21 and gross rearrangement of mitochondrial DNA. Subsets of renal oncocytomas show minimal karyotype alterations or translocation 11q13;? or loss of the Y chromosome and chromosome 1. There are some data suggesting that molecular genetic markers may be used not only for diagnosing of renal cell tumours but also for predicting the prognosis of tumour subtypes. Trisomy of chromosomes 7 and 17 and loss of the Y chromosome marks papillary renal cell adenomas, whereas additional trisomies such as those of chromosomes 3q, 8, 12, 16 and 20 are associated with papillary renal cell carcinomas. Although non-papillary renal cell tumours develop as a carcinoma, their clinical behaviour is in strong correlation with secondary karyotype changes such as loss of chromosomes 6q, 8p, 9 and 14q.

Consistent numerical chromosome aberrations in congenital fibrosarcoma

Cytogenetic analysis of a congenital fibrosarcoma of the volar forearm from a 2.5-month-old boy revealed a mosaic karyotype 46, XY 49, XY ,+]11,+]17,+]20. This pattern of specific trisomies provides additional support to the cytogenetic findings in five cases of congenital fibrosarcoma reported previously. Trisomy 11 appears to be characteristic of congenital fibrosarcoma with additional trisomies 8, 17, and 20 as common findings.

Molecular differential pathology of renal cell tumours.

Recent application of molecular cytogenetic techniques to the evaluation of renal cell tumours revealed four subtypes, each with a characteristic combination of genetic alterations within the chromosomal and mitochondrial DNA. The most common, nonpapillary renal cell carcinomas are characterized by the loss of chromosome 3p sequences, rearrangement of the chromosome 5q region and loss of the chromosome 14q sequences. Papillary renal cell tumours can be divided into two groups. Tumours with a combined trisomy of chromosomes 7 and 17 as well as loss of the Y chromosome are papillary renal cell adenomas. Tumours with additional trisomies such as trisomy 16, 20 or 12 are papillary renal cell carcinomas. Chromophobe renal cell carcinomas show a combination of allelic losses, which do not occur in other types of renal tumours. In addition, they have a rearrangement in the mitochondrial DNA. Renal oncocytomas are benign tumours marked by normal or abnormal karyotypes with balanced or unbalanced translocations and an altered restriction pattern of the mitochondrial DNA. Although the major cytological characteristics of renal cell tumours, such as clear, granular, chromophobe and oncocytic cell phenotypes correspond to nonpapillary, papillary and chromophobe renal cell carcinomas and renal oncocytomas, there are many cases with overlapping phenotype. Therefore, a classification of renal cell tumours based on specific genetic alterations is proposed.

Cytogenetics of papillary renal cell tumors

Chromosome aberrations were determined in short-term cultures of 18 papillary renal cell tumors, as well as in the cell line ACHN, and the results were evaluated together with 20 previously published cases. We found that chromosomes 7, 17, and 16 and the Y chromosome were specifically involved in the karyotype changes, marks benign papillary renal cell adenomas (ten cases). Malignant papillary renal cell carcinomas (29 cases) were characterized by additional trisomies: trisomy 16 occurred in 20 tumors, and trisomy 12 and 20 in 8 tumors each. Loss of the Y chromosome was observed in 7 of 9 benign and in 23 of 25 malignant tumors that developed in males. None of the papillary renal cell adenomas or carcinomas showed a loss of 3p or gain of a 5q segment, both of which are characteristic of common non-papillary renal cell carcinomas.

Trisomy 15 as a regular finding in chemically induced murine T-cell leukemogenesis.

Trisomy 15 is described as a common finding in all T-cell leukemias induced by a single dose of methylnitrosourea (MNU) in BDF1 mice and in the leukemias induced by 7 doses of benzo(a)pyrene. Additional trisomies were found in about half of the leukemias. The organ distribution suggests that the leukemic cells with trisomy 15 originate in the thymus. Trisomy 15 was detected in the thymus as early as 6 weeks after the application of MNU, i.e. during the latency period.

Cytogenetics of murine thymic lymphomas induced by N-methyl-N-nitrosourea: Difference in incidence of trisomy 15 in thymic lymphomas induced in neonatal and adult mice

Chromosome complements of murine thymic lymphomas induced by an alkylating agent N-methyl-N-nitrosourea (MNUA) were analyzed microscopically and karyotypically using the Q-banding technique. The chemical carcinogen was injected intraperitoneally into either neonatal or 7-week-old CFW/D mice. In addition, thymic lymphomas induced in 7-week-old AKR mice and thymic lymphomas developed spontaneously in this strain were also examined. All six lymphomas induced in neonatal CFW/D had hyperdiploid cell lines that accounted for 90% of the cells analyzed. Chromosome analysis of lymphomas induced in adult CFW/D mice showed that only four out of nine lymphomas had predominantly hyperdiploid cell lines. The remaining five lymphomas had diploid modal chromosome number although they also carried a variant line characterized by 41 chromosomes. All eight lymphomas induced in adult AKR mice and six out of seven spontaneous AKR lymphomas showed predominantly diploid modal line. The remaining spontaneous lymphoma had a hyperdiploid stem line of 41 chromosomes. Microscopic and karyotypic analysis further identified trisomy 15 as the regular chromosome abnormality in the hyperdiploid cells in lymphomas of each group, whereas cells with diploid chromosome number had no detectable chromosome abnormality. Additional trisomies were also found, but their appearance was restricted to individual tumors. Thus, the incidence of trisomy 15 in lymphomas induced by MNUA in adult CFW/D and AKR mice, as well as in the spontaneous AKR lymphomas, is significantly lower than that in lymphomas induced in neonatal mice by the same carcinogen.

Chronic Myeloid Leukemia With Permanent Disappearance of the Ph Chromosome and Development of New Clonal Subpopulations

A 6.5-yr follow-up study is reported on a case of chronic myeloid leukemia (CML) diagnosed in 1971 in a man of age of 19 yr. At that time the Ph 1 chromosome was found in all of his bone marrow cells. After 4 yr of intermittent treatment his blood and bone marrow still showed a florid CML picture, but the karyotypes of bone marrow, blood, and spleen cells were normal. Blastic transformation occurred after 5.5 yr and was accompanied by a hyperdiploid karyotype (49,XY,+9,+ 10, + 12) without reappearance of the Ph 1 chromosome. After successful chemotherapy the karyotype again became normal. In 1977 cells with a new clonal aberration (14p+) gradually became the dominating bone marrow cell population, while the peripheral blood was compatible with CML. The 14p+ clone subsequently decreased at the expense of the 49,XY,+9,+ 10,+ 12 clone, which had reappeared in the majority of the dividing blood cells. Also, a new clonal subpopulation 45,XY,t(5p; 17q) was found in 7% of the metaphases. This coincided with the occurrence of a second blast transformation, which was treated with chemotherapy. The karyotypes of all dividing cells during the recovery from the induced severe bone marrow hypoplasia still showed the t(5p; 17q) abnormality and chromosome numbers varying from 45 to 51. In some cells additional trisomies were seen as an indication of a clonal evolution. One month before the patient’s death a fourth abnormal cell line was seen in 10% of the dividing blood cells.

29 The Distribution of Chromosome Aberrations in Time: Chromosome Studies in Newborn and Spontaneous Abortion Populations

In a 36 month period involving 9000 newborns, three clusterings of autosomal chromosomal trisomies were recognized. Using the last menstrual period for estimating time of conception, the first cluster extended from October through December, 1963, and included 3 cases; the second cluster, June and July, 1964, 3 cases; and the third cluster, December, 1964 through June 1965, 5 cases. In the remaining 24 months, only 2 other cases were observed. Retrospective studies for the first cluster revealed: 1. 8 additional trisomies in nearby Chicago hospitals; 2. a significant increase in the number of stillbirths and conceptions that expired with congenital malformations at Michael Reese Hospital; 3. a similar clustering of chromosome abnormalities in newborns in Denver, Colorado (PUCK and ROBINSON, Science [1965]) and in spontaneous abortions in London, Ontario (CARR, personal communication). For the second cluster there was a corresponding increase in the abortion population in Canada. There was no statistically significant increase in the reported incidence of 9 infectious diseases including rubella or infectious hepatitis, relative to the three clusterings defined in the newborn population. Prospective studies on the distribution of chromosome aberration in time have been conducted since November, 1964, and reveals that when the spontaneous abortion and newborn populations are considered as one conceptual population, the distribution of chromosome aberrations in time appears random. These findings indicate that either the factors responsible for nonrandom distribution of chromosome aberrations were not operating during the time period covered or that onrandom distribution of chromosome aberrations does not occur in the human population. (APS)