Chromosome studies in polycythemia vera.

Polycythemia vera (PV) represents an apparent monoclonal stem cell proliferation with a frequent transition to full neoplastic behavior. Up to 26% of untreated PV patients can be expected to have some chromosome abnormalities in the marrow at the time of diagnosis, and 10--15% have an abnormal cell line or clone. Both structural and numerical aberrations occur. Aneuploidy is the most common type of chromosome abnormality, however, with hyperdiploid clones occurring more frequently than hypodiploid clones. Chromosomes 1, 8, 9 and 20 are involved in a non-random pattern, and aberrations of all the F group, or at least the No. 20 chromosome seem to be associated to some extent with diseases involving erythroid hyperplasia. Leukemia develops in a certain percentage of patients regardless of the type of treatment they have received, but the relationship, if any, between the chromosome abnormalities and the development of leukemia is still uncertain. The abnormal clones that occur in PV appear to be quite stable and there is no indication at this time that they correlate with a prognosis of leukemic transformation.     

Incidence of numerical chromosome aberrations in meningioma tumors as revealed by fluorescence in situ hybridization using 10 chromosome-specific probes

OBJECTIVE: Although information on the cytogenetic characteristics of meningioma tumors has accumulated progressively over the past few decades, information on the genetic heterogeneity of meningiomas is still scanty. The aim of the present study was to analyze by interphase fluorescence in situ hybridization (FISH) the incidence of numerical abnormalities for chromosomes 1, 9, 10, 11, 14, 15, 17, 22, X, and Y in a group of 70 consecutive meningioma tumors. Another goal was to establish the potential associations among the altered chromosomes, as a way to assess both intertumoral and intratumoral heterogeneity. METHODS: For the purpose of the study, 70 patients diagnosed with meningioma were analyzed. Interphase FISH for the detection of numerical abnormalities for chromosomes 1, 9, 10, 11, 14, 15, 17, 22, X, and Y was applied to fresh tumor samples from each of the patients studied. RESULTS: The overall incidence of numerical abnormalities was 76%. Chromosome Y in males and chromosome 22 in the whole series were the most common abnormalities (46% and 61%, respectively). Despite the finding that monosomy of chromosome 22/22q(-) deletions are the most frequent individual abnormality (53%), we have observed that chromosome gains are significantly more common than chromosome losses (60% versus 40%). Chromosome gains corresponded to abnormalities of chromosomes 1 (27%), 9 (25%), 10 (23%), 11 (22%), 14 (33%), 15 (22%), 17 (23%), and X in females (35%) and males (23%) whereas chromosome losses apart from chromosome 22 frequently involved chromosomes 14 (19%), X in males (23%), and Y in males (32%). Although an association was found among most gained chromosomes on one side and chromosome losses on the other side, different association patterns were observed. Furthermore, in the latter group, monosomy 22/22q(-) was associated with monosomy X in females and monosomy 14/14q(-) was associated with nulisomy Y in males. In addition, chromosome losses usually involved a large proportion of the tumor cells whereas chromosome gains were restricted to small tumor cell clones, including tetraploid cells. CONCLUSIONS: Our results show that meningiomas are genetically heterogeneous tumors that display different patterns of numerical chromosome changes, as assessed by interphase FISH.     

Cytogenetic analysis of retinoblastoma: evidence for multifocal origin and in vivo gene amplification

Retinoblastoma (Rb) is an uncommon childhood tumor of the neural retina with a significant genetic component in its etiology. A small proportion of patients have a deletion in chromosome 13 encompassing band 13q14, an observation which permitted the assignment of the RB1 locus to this region. About 20% of Rb tumors exhibit microscopic deletions of band 13q14 or monosomy 13. Trisomy 1q and i(6p) have also been reported in a high percentage of tumors. We analyzed the chromosome complements from direct preparations of 10 Rb tumors derived from seven patients. Modal chromosome numbers ranged from 45 to 48, and occasional duplications of the genomes were noted. In general, the tumors were chromosomally stable, although karyotypic evolution and random chromosome loss were encountered. Consistent abnormalities included trisomy 1q, i(6p), 6q-, and del(13)(q12----14). One patient with bilateral Rb had three tumor clones (two in one eye and one in the other) with chromosome abnormalities unrelated in origin. A second patient with unilateral Rb had two tumor clones with chromosome abnormalities again unrelated in origin. These two patients provide some of the first cytogenetic evidence for the multifocal origin of primary Rb. In the untreated tumor of a third patient, a homogeneously staining region (HSR) was detected in 1p32, indicating gene amplication in vivo; previously, an HSR at this site has been reported in the established Rb cell line Y79.     

Cytogenetic and molecular cytogenetic investigations in relapse of B-cell chronic lymphocytic leukemia

Сhromosomal abnormalities have been analyzed in bone marrow cells of 61 patients with relapse of B-cell chronic lymphocytic leukemia. The cytogenetic results have allowed the structural stratification of the obtained karyotypes into ten groups of clones: normal, normal/near tetraploid, abnormal/normal, abnormal/ near tetraploid/normal, evolution of clonal chromosome abnormalities; evolution of clonal chromosome abnormalities/normal, evolution of clonal chromosome abnormalities/near tetraploid/normal, independent clones, independent/normal clones; and independent/near tetraploid/normal clones. The identified structural rearrangements included translocations, deletions, insertions, and duplications; however, deletions with the involvement of bands 17p12, 13q12–q14, 11q14, and 11q23 dominated (63.8%). The application of i-FISH helped to show the presence of one to four abnormalities per karyotype. The identified cytogenetic and molecular cytogenetic rearrangements may signify a multilevel nature of the process underlying the development of resistant karyotypes. The results obtained under both methods have revealed the presence of a heterogenic cell population with possibly different levels of chemotherapy resistance.     

Multiple congenital abnormalities in a newborn with two supernumerary marker chromosomes derived from chromosome 14

Pure partial duplication or triplication of the proximal part of chromosome 14 has been reported in only 4 patients. Other individuals with a duplication or triplication of this region have additional chromosome imbalances. We present a new case with a supernumerary marker chromosome in all blood cells and in 35% of the cells an additional smaller marker chromosome. Both markers appeared to be derived from chromosome 14 (del(14)(q21.2) in all cells and del(14)(q11.2) in 35% of the cells). This results in a partial duplication of the proximal region of chromosome 14, combined with a mosaic partial triplication of a smaller segment of the same region. In this paper, we compare the clinical features of this case to those of cases from the literature. Although most of the patients from literature were unbalanced translocation carriers, their clinical features were comparable, except from renal abnormalities.     

Low incidence of deletion of the esterase D locus in retinoblastoma patients

Esterase D was quantitatively measured in the red blood cells from three patients from three separate kindreds who had abnormalities of chromosome 13. The esterase D activity was proportional to the number of copies of the q14 region of chromosome 13 present. These findings confirm published data localizing the esterase D gene to chromosome band 13q14, a region which is important in the etiology of retinoblastoma. Fifty-one additional retinoblastoma patients not known to have any chromosomal defect also underwent esterase D determination. In none of these patients did the esterase D measurement detect a 13q14 deletion. The normal esterase D levels in this series of 51 retinoblastoma patients suggest that deletion of an esterase D locus is infrequent in retinoblastoma patients. It must be noted that patients who are mosaics, with a 13q14 deletion in only a fraction of all somatic cells, could possibly have normal red blood cell esterase D levels. Further study is necessary to determine if esterase D determination of all retinoblastoma patients is a worthwhile clinical tool.     

FISH Variants with D15Z1

We present our experience with cross-hybridization of D15Z1, used in combination with D15S10, D15S11 or SNRPN, in 109 clinical cases referred for Angelman syndrome (AS), Prader-Willi syndrome (PWS), for autism to rule out duplication of 15q11.2, or to identify structural chromosome abnormalities thought to involve chromosome 15. Nine cases with normal karyotypes studied with at least one of these probe mixtures showed an extra signal with D15Z1 on a chromosome 14. One case showed absence of the D15Z1 signal from 15p and one case showed an extra signal with D15Z1 on both chromosome 14s. Sixteen cases from this series had structural abnormalities, which included ten cases with supernumerary markers, three of which had a D15Z1 signal on a chromosome 14. The remaining cases did not have an extra signal on chromosome 14, but included rearrangements between Y and 15, 15 and 19, and a r(15), all with breakpoints in 15p11.1 or p11.2. Of the three cases with a supernumerary marker and an extra D15Z1 signal on a chromosome 14, one was a maternally derived marker, while the variant 14 was paternal in origin. The other two markers were de novo. The high frequency of variant 14 in cases with supernumerary markers (30%) was not significant by Chi-square analysis compared to the overall frequency in 109 cases of 11.9%. The overall frequency is consistent with a previous report by Stergianou et al. (1993). We can now add that a false-negative result may occur slightly less than 1% of the time. The chance that both chromosome 14 homologs will be positive for D15Z1 is theoretically about 1 in 300. If associated with an abnormal phenotype, the possibility of uniparental disomy should be ruled out.     

Hairy cell leukemia: an analysis of the chromosomes of 26 patients.

We studied the chromosomes from 26 patients with hairy cell leukemia (HCL) to ascertain the frequency and types of consistent chromosomal abnormalities. Samples from 21 patients were obtained from peripheral blood cultures grown 24 and 48 h without phytohemagglutinin, or from bone marrow samples. Two male patients had similar, consistent abnormalities; one patient's karyotype was 46, X, +12; that of the second was 46, X, +C marker. In the latter case, the distal long arm of the C marker most closely resembled chromosome No. 12 from band q14 to q terminal, but the short arm and proximal long arm were of undetermined origin. Both karyotypes lacked the Y chromosome. Nine of the 21 patients had abnormalities in single cells. One patient had, in one sample, a single abnormal cell with an extra No. 3 and an extra No. 12 (48, XY, +3, +12), and in a later sample, a second cell of poor morphology which also could have been trisomic for No. 12. Another patient had one cell with an unusually bright short arm, as well as two cells, with different abnormalities, both involving the short arm of chromosome No. 1. The two patients with consistent chromosome abnormalities had rapidly progressive disease in spite of splenectomy, and their clinical course from the time of diagnosis was relatively short (5 and 7 months, respectively).     

Cytogenetic patterns in acute nonlymphocytic leukemia.

Analysis of chromosomal banding patterns in acute nonlymphocytic leukemia (ANLL) reveals that approximately 50% of patients have an abnormal karyotype. Although there is substantial variability, certain nonrandom abnormalities occur, e.g., +8, -7, and the 8;21 translocation (often accompanied by loss of an X or Y chromosome). The 15;17 translocation appears to be highly specific for acute promyelocytic leukemia. These abnormalities usually are not seen in remission, but reappear in relapse, sometimes exhibiting further clonal evolution; a +8 is the most frequently observed evolutionary change. Patients with ANLL following treatment of a malignant lymphoma tend to have hypodiploid modal numbers and frequently show loss of a chromosome No. 5 or No. 7.     

Detection of an unbalanced translocation (4;14) in a mildly retarded father and son by flow cytometry

Summary A child with impaired intelligence, minor dysmorphisms, obesity and genital hypoplasia was found to have an apparently balanced translocation, 46,XY,t(4;14)(q12;q13), following cytogenetic analysis. The same rearrangement was also detected in the child's father, who had similar phenotypic abnormalities to his son. Detailed study of flow karyotypes produced from lymphoblastoid cell lines established that in both patients the translocation was in fact unbalanced with approximately 11 million base pairs of DNA (corresponding to about 6.0% of chromosome 4 or 11.0% of chromosome 14) being lost.     

Clinical and cytogenetic manifestations of subtelomeric aberrations: Report of six cases

BACKGROUND: Fluorescent subtelomeric probes for the 41 different subtelomeric regions (the p arms of the acrocentric chromosomes were excluded) have been developed over the last 10 years. These probes can detect deletions, duplications, and translocations in the gene-rich subtelomeric regions of human chromosomes, regions where crossing over frequently occurs and where a high number of abnormalities have been found. Recently, commercially produced probes have become available, which has led to the detection of subtelomeric abnormalities in 7.4% of patients with moderate to severe mental retardation (Knight et al., 1999). CASES: We evaluated 43 dysmorphic children with developmental delay and/or mental retardation of unknown etiology and/or autism who were previously assessed for chromosome abnormalities, metabolic disorders, or recognizable dysmorphic syndromes, all of which were ruled out. Of the 43 children tested, 6 (14%) were found to have subtelomeric aberrations. CONCLUSIONS: We recommend that patients with dysmorphic features and mental retardation of unknown etiology who also have a normal standard chromosome analysis should have subtelomeric FISH testing performed earlier in their clinical workup.     

Unbalanced 1q whole-arm translocation resulting in der(14)t(1;14)(q11-12;p11) in myelodysplastic syndrome

Unbalanced whole-arm translocations (WATs) of the long arm of chromosome 1, resulting in complete trisomy 1q, are chromosomal abnormalities detectable in both solid tumors and hematologic neoplasms. Among the WATs of 1q to acrocentric chromosomes, a few patients with der(1;15) described as a dicentric chromosome have been reported so far, whereas cases of der(1;14) are much rarer. We report on a case of der(1;14) detected as single anomaly in a patient with myelodysplastic syndrome. The aim of our work was to investigate the breakpoints of the (1;14) translocation leading to the der(1;14). Fluorescence in situ hybridization (FISH) experiments have been performed on chromosome preparations from bone marrow aspirate, using specific centromeric probes of both chromosomes, as well as a probe mapping to 1q11 band. FISH results showed that in our patient the derivative chromosome was monocentric with a unique centromere derived from chromosome 14. The breakpoints of the translocation were located in the short arm of chromosome 14 and in the long arm of chromosome 1, between the alphoid D1Z5 and the satellite II domains. The 1q breakpoint was within the pericentromeric region of chromosome 1, which is notoriously an unstable chromosomal region, involved in different chromosomal rearrangements.     

A study of cryptic terminal chromosome rearrangements in recurrent miscarriage couples detects unsuspected acrocentric pericentromeric abnormalities

Fifty chromosomally normal couples with three or more miscarriages were examined using fluorescent in situ hybridisation (FISH) and a library of subtelomere-specific probes together with alphoid repeats mapping to the acrocentric centromeres. Six abnormalities were found. Firstly, a cryptic reciprocal subtelomere translocation between the long arm of a chromosome 3 and the short arm of a chromosome 10. The other five cryptic abnormalities involved the acrocentric chromosome pericentromeric regions and in one case also Yp. Two patients had a rearranged chromosome 13, where the centromeric region was found to be derived from the short arm, centromere and proximal long arm of chromosome 15. Another two patients had a derived chromosome 22, where the centromere was replaced by two other centromeres, one derived from chromosome 14 and the other from either chromosome 13 or 21, while one patient had the subtelomere region of Yp translocated onto the short arm of a chromosome 21. These abnormalities may be the underlying cause of the recurrent miscarriages, because they may result in abnormal pairing configurations at meiosis leading to non-disjunction of whole chromosomes at metaphase I. The frequency of rearrangements seen in the recurrent miscarriage patient population was significantly different from that in the control group ( P=0.0096, Fisher's exact test) due to the acrocentric pericentromeric abnormalities.     

Involvement of knob heterochromatin in mitotic abnormalities in germinating aged seeds of maize.

Seeds of three inbred lines of maize, with contrasting numbers of heterochromatic knobs and stored under two different ageing treatments, were analyzed for the occurrence of abnormalities at mitotic anaphase in root meristems 3, 7, 21,42, and 56 days after germination, and in root meristems of their freshly harvested selfed progeny. The largest category of detectable aberrations involved breakage of knobbed chromosome arms. We have obtained evidence that knob heterochromatin plays a central role in the origin of primary chromosome bridges. The initial event responsible for the occurrence of breakages and lagging chromosomes was characterized by the nondisjunction of newly replicated sister chromatids, which was observed to occur preferentially at the knob level. Such configurations, and all the other types of abnormalities (as for example, lagging chromosomes, typical chromosome bridges, fragments, and micronuclei), were observed at decreasing frequencies throughout root growth. Nevertheless, we have detected the occurrence of breakage-fusion-bridge cycles that were initiated by broken chromosomes. The relationship between late-replicating DNA in maize knob heterochromatin and the vulnerability of such regions to breakage is discussed. Our observations suggest a similarity between the mechanisms involved or associated with the origin of the described abnormalities and those reported to occur in cultured maize cells.     

Cytogenetic survey of 117 Tunisian patients with de novo myelodysplastic syndrome

Cytogenetic studies were performed on 117 Tunisian patients with de novo myelodysplastic syndromes (MDS). According to the French-American-British (FAB) criteria 40 patients presented with refractory anaemia (RA, 34%), eight with refractory anaemia with ringed sideroblasts (RARAS, 7%), 19 with refractory anaemia with excess of blasts (RAEB, 16%), 16 with refractory anaemia with excess of blasts in transformation (RAEB-t, 14%), 18 had chronic myelomonocytic leukaemia (CMML, 15%) and 16 unclassifiable MDS (14%). Seventy-five were men and forty-two were women. Five were children and 112 were adults with a median age of 58 years. Fifty-five per cent of the patients presented clonal chromosome abnormalities. Rates of abnormality varied from one FAB subtype to the other: 55% in RA, 75% in RARAS, 63% in RAEB, 75% in RAEB-t and 28% in CMML. The most frequent chromosome abnormalities were del(5q) (22 cases), monosomy 7 (12 cases), del(12p) (6 cases), and trisomy 8 (5 cases). Rare abnormalities were also found: ring of chromosome 12 and trisomy 15. Conventional cytogenetics remains the basic technique in identifying chromosomal abnormalities associated with MDS.     

无精和严重少精症患者的遗传缺陷分析——-附2例世界首报染色体异常核型

对217例无精和严重少精症患者外周血淋巴细胞染色体核型进行分析,并采用聚合酶链反应对7例Y染色体结构异常患者的AZFc区进行检测。发现187例无精症患者中检出异常核型77例（41.18%）（其中46,XY,t(6;14)(p21;p13),46,XY,t(8;12)(p21;q24)为世界首报核型）,主要涉及染色体异常（数目异常和结构异常）;染色体异态（Y染色体异态和9号染色体臂间倒位）及46,XX性反转;30例严重少精症患者中检出异常核型4例（13.33%）（结构异常和46,XX性反转）。由此可见,性染色体数目和结构异常是精子发生障碍的主要原因,其次常染色体的某些断裂点也可能影响精子发生。AZFc区的缺失与否与精子发生也有直接关系。     

Karyotype instability with multiple 7/14 and 7/7 rearrangements

Summary Chromosomes were studied in a mentally retarded boy with microcephaly, growth retardation, facial erythema, café-au-lait spots, and IgA deficiency. In the lymphocytes there was a remarkable tendency to exchange parts of the chromosomes Nos. 7 and 14, the translocations almost exclusively taking place in bands 7p13, 7q32 and 14q11. Seven different types of rearrangements between Nos. 7 and 14, and some other chromosomal aberrations were found. No abnormalities could be detected in the bone marrow. The patient somewhat resembles those affected with ataxia-telangiectasia or with Bloom's syndrome, but on clinical and cytogenetic grounds these disorders could be excluded.7/14 Translocations similar to those found in our patient's lymphocytes have been reported to occur very rarely in the lymphocyte cultures of individuals with apparently normal chromosome constitution. A relationship between these phenomena may exist.     

Assessment of X bends in patients with atypical X chromosome phenotypes.

Several patients with X chromosome structural abnormalities have been more severely affected clinically than expected. Since bends at Xq13-21 have been associated with inactivation, the authors scored bends retrospectively in 62 patients with X chromosome aneuploidy and 21 cases with structural abnormalities of the X chromosome. They found that patients with 2 X inactivation sites where one X was structurally abnormal had significantly fewer cells with X bends than normal 46,XX. In addition, these patients also showed X bends on the normal X more often than would be expected if non-random X inactivation of the abnormal X chromosome was occurring. Five of the 6 patients with a short or long arm deletion or paracentric inversion of Xq were mentally retarded or had other congenital anomalies not usually associated with Turner syndrome. This suggests to them that these clinical findings may be related to interference with X inactivation patterns in cells with a structurally abnormal X chromosome.     

Greig syndrome associated with an interstitial deletion of 7p: confirmation of the localization of Greig syndrome to 7p13

Summary An 11-month-old infant with Greig cephalopolysyndactyly syndrome and mild developmental delay is described. High-resolution chromosomal analysis showed a de novo interstitial deletion of chromosome 7p with breakpoints located at p13 and p14. Cytogenetic analysis of polymorphisms of the heterochromatin in the pericentromeric region suggested the deleted chromosome was of paternal origin. This case confirms the localization of Greig syndrome to 7p13 and emphasizes the importance of performing cytogenetic studies on patients with Mendelian disorders who have unusual findings or cognitive abnormalities in a disorder usually associated with normal intellect. Review of clinical features in published reports of patients with a deletion involving 7p13 showed a number to have features overlapping with Greig syndrome. Because of this, we suggest that cytogenetic aberrations, particularly chromosomal microdeletions, may represent a significant etiology for Greig syndrome.