Cigarette smoking and chromosome 9 alterations in bladder cancer

Epidemiological studies suggest that bladder cancer may be caused by carcinogens in tobacco and certain occupational exposures. Molecular studies have shown that chromosome 9 alterations and TP53 mutations are the most frequent events in bladder cancer. To date, the relationships between epidemiological risk factors and genetic alterations have not been fully explored in bladder cancer. The purpose of this study was to explore the association between smoking and chromosome 9 aberrations in bladder cancer cases. Seventy-three patients with bladder cancer at Memorial Sloan-Kettering Cancer Center were evaluated for smoking history, occupational history, and chromosome 9 alterations. The epidemiological data were abstracted from medical charts. Patients' tumor tissues were analyzed using RFLP and microsatellite polymorphism assays for detection of chromosome 9 alterations. Elevated odds ratios (ORs) were found for chromosome 9 alterations in smokers compared to those in nonsmokers (OR = 4.2; 95% confidence interval, 1.02-17.0) after controlling for age, sex, race, occupational history, and stage of disease. The ORs were 3.6 for those smoking < or = 20 cigarettes per day and 5.8 for those smoking > 20 cigarettes per day. No association was found between occupational history and chromosome 9 alterations. This study supplies evidence suggestive of the link between smoking and chromosome 9 alterations in the etiology of bladder cancer and indicates that potential tumor suppressor genes on chromosome 9 may be involved in smoking-related bladder carcinogenesis.

Chronic granulocytic leukemia: recent information on pathogenesis, diagnosis, and disease monitoring

Current evidence strongly implicates the chromosome translocation t(9;22)(q34;q11.2) as the cause of chronic granulocytic leukemia. Therefore, identification of this genetic abnormality through either cytogenetic or molecular methods has become a requirement for diagnosis. Intense investigation of the mechanism by which t(9;22) transforms normal hematopoietic progenitors into malignant cells is ongoing. Recent advances in molecular diagnostic methods have allowed refined qualitative and quantitative methods of detecting t(9;22), which are useful for monitoring response status and detecting minimal residual disease. The current understanding of the pathogenesis of chronic granulocytic leukemia and the application of new diagnostic methods are discussed.

Achievement of a complete cytogenetic response with hydroxyurea in a patient with chronic myelogenous leukemia

Hydroxyurea rarely produces a complete cytogenetic remission in patients with chronic myelogenous leukemia (CML). In this report, we describe one case of the CML patient who achieved complete cytogenetic remission (no Ph chromosome in 20-25 metaphase cells) by treatment with hydroxyurea alone. By the fluorescent in situ hybridization (FISH) methodology using bcr/abl specific translocation probe, sequential bone marrow specimens from the patient showed the characteristic 9;22 translocation at a higher rate (9-10%) than the normal control range (2.49-4.88%) at the time of complete cytogenetic remission. Thus, it is suggested that FISH is a more sensitive method to detect the bcr/abl fusion gene than conventional cytogenetic analysis for the detection of minimal residual disease in CML.

Deletions of distal 9p associated with 46,XY male to female sex reversal: definition of the breakpoints at 9p23.3-p24.1

Monosomy of distal 9p is associated in rare cases with abnormalities of testicular determination, which can lead to male to female sex reversal in a 46,XY genetic background. We present two 46,XY individuals partially monosomic for 9p who were raised as females. Definition of the breakpoints using somatic cell hybrids containing only the rearranged chromosome 9 indicated that in the first patient the breakpoint was located between markers D9S256 and D9S144 and in the second patient, the breakpoint was distal to the marker D9S144. In both cases this corresponds to the cytogenetic position 9p23.3-p24.1. Analysis of highly polymorphic microsatellite markers demonstrated a paternal origin of the rearranged chromosome 9 in both patients. These studies define the minimum region associated with male to female sex reversal as 9p24.1-pter.

Assignment of the dynamin-1 gene (DNM1) to human chromosome 9q34 by fluorescence in situ hybridization and somatic cell hybrid analysis

The dynamins are recently discovered GTP-binding proteins postulated to mediate the scission of clathrin-coated vesicles at the plasma membrane. Of the three known mammalian dynamins, dynamin-1 (DNM1) appears to be particularly important for the formation of synaptic vesicles at presynaptic nerve termini. To investigate the possibility that mutations in the DNM1 gene cause a human disease, we determined the chromosomal localization of human DNM1. We conclude from fluorescence in situ hybridization and from the analysis of somatic cell hybrids that the map position in 9q34. This region has syntenic homology with mouse chromosome 2p, in agreement with the map position of the mouse DNM1 gene [see accompanying article by Klocke et al. (1997, Genomics 41:290-292)]. We discuss the potential relevance of the human DNM1 localization to diseases that were mapped genetically to the same chromosomal region.

Constitutional mosaicism for a chromosome 9 inversion resulting in recombinant aneusomy in an offspring

We report on a case of constitutional mosaicism for a large pericentric inversion of chromosome 9 in a man whose daughter had recombinant aneusomy resulting in partial 9q duplication and partial 9p deletion. At age 6 months, the girl was evaluated because of congenital anomalies [corrected] and developmental delay. Chromosomal analysis on this infant showed a derivative chromosome 9 which was later determined to be a recombinant chromosome with trisomy of 9q34.1-->qter and monosomy of pter-->9p24. Chromosomal analysis in her father showed the presence of two cell lines; 75% of lymphocytes had a 46,XY pattern, and 25% had a 46,XY,inv(9)(p24q34.1) karyotype. The infant's physical findings represent a composite of the reported cases of both trisomy 9q34.1-->qter and monosomy pter-->9p24. The infant's father was phenotypically and cognitively normal. This case broadens the spectrum of reported cases of mosaicism for an autosomal structural rearrangement generating unbalanced gametes, and further supports the tenet that constitutional mosaicism has clinical relevance for genetic counseling.

Various types of hereditary inclusion body myopathies map to chromosome 9p1-q1

Hereditary inclusion body myopathies are a clinically heterogeneous group of disorders characterized by adult-onset, slowly progressive muscle weakness and typical histopathology: rimmed vacuoles and filamentous inclusions. The disorders are usually inherited as an autosomal recessive trait. The gene responsible for the disease found in Iranian Jews, who present with quadriceps-sparing myopathy, maps to chromosome 9p1-q1. We address the question of whether hereditary inclusion myopathies are genetically as well as clinically heterogeneous disorders. We mapped the disease gene segregating in two families of Afghani-Jewish and one family of Iraqi-Jewish descent to the chromosome 9 locus. Similarly, the disease gene segregating in a non-Jewish family from India mapped to the same locus. By contrast, the disease gene segregating in a French-Canadian family in which affected individuals had central nervous system involvement as well as hereditary inclusion body myopathy, did not map to this locus. We conclude that many but not all forms of autosomal recessive hereditary inclusion body myopathy are caused by a gene defect that maps to chromosome 9p1-q1.

Acute myeloid leukemia with t(6;9) (p23;q34): association with myelodysplasia, basophilia, and initial CD34 negative immunophenotype

The translocation (6;9)(p23;q34) is a rare cytogenetic aberration found in patients with acute myeloid leukemia (AML). The clinical, morphologic, and immunophenotypic findings of eight t(6;9) acute leukemias are described. The patients included six men and two women with a mean age of 38.5 years. The leukemias were classified in the French-American-British (FAB) system as AML FAB M2 in four cases and as FAB M4 in four cases. Underlying myelodysplasia was evident in six cases. Bone marrow basophilia was found at presentation in six of the seven cases studied. In two cases with basophilia, darkly stained granules were also present in many eosinophils. In one case, initial basophilia was absent, but was present at relapse, as were eosinophils containing darkly stained granules. Iron stains were available in five cases; four showed increased incorporation and three had ringed sideroblasts. All cases studied by flow cytometry (six at presentation and three at relapse) expressed CD13, CD33, and human leukocyte antigen-DR. At presentation, five cases were CD34 negative. In one case at presentation, a subset of blasts (18%) weakly expressed CD34. Three cases studied at relapse were positive for CD34. Two of seven cases studied were terminal deoxynucleotidyl transferase positive. The t(6;9)(p23;q34) was the only cytogenetic abnormality in five cases. Trisomy 8 was found in two cases, and ring 12 was present in one case. Three patients are living with refractory leukemia 6 weeks to 6 months after initial diagnosis, and three patients died of complications of allogeneic bone marrow transplantation. Only one patient is alive without evidence of disease 3 years after bone marrow transplantation. t(6;9) leukemia is an unusual type of AML that is associated with poor prognosis, early age of onset, basophilia, myelodysplasia with frequent ringed sideroblasts, and a CD34-negative initial phenotype.

Involvement of the chromosomal region 11q13 in renal oncocytoma: case report and literature review

Renal oncocytomas comprise a cytogenetically heterogeneous group of tumors consisting potentially of cytogenetic distinguishable subgroups. Review of the literature revealed loss of chromosome 1 and Y as a possible anomaly for at least one subset oncocytomas. The frequent finding of rearrangements involving chromosome 11 band q13 characterizes another subset of oncocytomas. We report the cytogenetic and pathological features of a renal oncocytoma diagnosed in a 72-year-old woman and found a t(9;11)(p23;q13) as a consistent abnormality. This supports the idea that translocations involving 11q13 define a further subset of oncocytoma.

Sexual function and clinical features of patients with Klinefelter's syndrome with the chief complaint of male infertility

In this report, we present the overall sexual function and clinical features of patients with Klinefelter's syndrome with the chief complaint of male infertility. The study consisted of 40 patients with a control group of 55 infertile non-azoospermic males with a normal 46,XY karyotype who visited the Reproduction Center of Toho University Hospital during the 5.5-year period between January 1991 and June 1996 with the chief complaint of male infertility. Among the 40 patients with Klinefelter's syndrome, 38 cases were pure 47,XXY, one case was 47,XXY with a pericentric inversion of chromosome 9 and one case was a mosaic of 46,XY/47,XXY(2:28). Thirty-nine of these 40 patients were azoospermic and one (47,XXY) had severe oligoasthenozoospermia. The sexual function of the patients was evaluated according to their responses to a preliminary questionnaire devised by our department. There was no significant difference in the frequency of sexual function disturbances between the patients with Klinefelter's syndrome and the control group (67.5% vs. 60.0%; chi 2 analysis; p = 0.454). The mean frequency of sexual intercourse per month in the patients with Klinefelter's syndrome was significantly higher than in the control group (4.4 +/- 2.8 vs 3.3 +/- 1.6: Welch's t-test, p < 0.05). A possible explanation for this variation may lie in the fact that many of these patients were diagnosed with azoospermia poor to the administration of the questionnaire and may have wished to continue to have relations as a couple.

Molecular events in chronic myeloid leukemia progression

Chronic myelogenous leukemia presents two distinct clinical phases: the chronic phase is characterised by a marked expansion of the myeloid compartment which still retains a normal differentiative capacity, whereas a differentiation block is the clinical hallmark of the acute transformation. The molecular mechanism underlying the CML progression are still poorly understood. The occurrence of additional molecular lesions, involving the p53, the RAS and the p16 genes may complement and fulfil the BCR/ABL transforming potential, finally leading to an acute leukemic phenotype. However, several lines of evidence suggest that also quantitative changes of the BCR/ABL transcript amounts could explain the progression of the leukemic phenotype in the BCR/ABL-positive hematologic malignancies.

Detection of numerical chromosomal aberrations in malignant melanomas using fluorescence in situ hybridization

To evaluate the numerical chromosomal aberration in malignant melanoma, we have applied fluorescence in situ hybridization (FISH) with repetitive DNA probes specific for chromosomes 1, 6, 7, 9, 10, and 17 on 24 fresh malignant melanomas (primary: 14, metastatic: 8). We defined a tumor that had copies with more than 3 spots as chromosomal gain. Chromosomal copy number gain was found in 40.9% of the cases for chromosome 7, 27.2% for chromosome 6, 27.2% for chromosome 17, 22.7% for chromosome 9 and 10, and 4.5% for chromosome 1. Monosomy was found in 54.5% of the cases for chromosome 10, 36.5% for chromosome 9, 27.2% for chromosome 6, 22.7% for chromosome 17, and 18.1% for chromosome 1 and 7. The most frequent numerical alterations were seen in chromosomes 6, 7, 9 and 10. Gain of chromosome 6 and 7 and/or losses of chromosome 9 and 10 may play an important role in the tumorigenesis and development of malignant melanomas.

Impaired male sex development in an infant with molecularly defined partial 9p monosomy: implication for a testis forming gene(s) on 9p

This paper describes a genetically male infant with impaired male sex development and partial 9p monosomy. The external genitalia were ambiguous with microphallus (penile length at birth 10 mm, mean age matched normal length 29 mm (SD 5)), hypospadias, and hypoplastic scrotum. The tests were undescended and severely hypoplastic (testis size at 12 months of age, right 8 x 5 x 4 mm and left 4 x 3 x 2 mm; mean age matched normal size, length 18 mm (SD 2), width 11 mm (SD 1). Cytogenetic studies showed a 46,XY,del(9)(p23) karyotype in all the 30 peripheral lymphocytes and 20 skin fibroblasts examined. Microsatellite analysis for a total of 13 loci assigned to the 9p22-24 region showed that the deleted chromosome 9 was of paternal origin and was missing a region distal to D9S168. Southern blot analysis for D9S47 also confirmed the 9p deletion. The sequence of SRY was normal. The results provide further support for the previously proposed hypothesis that a gene(s) for testis formation is present on the distal part of 9p and indicate in molecular terms that the putative testis forming gene(s) resides in the region distal to D9S168.

Identification and sizing of the GAA trinucleotide repeat expansion of Friedreich's ataxia in 56 patients. Clinical and genetic correlates

Fifty-six patients with a clinical diagnosis of Friedreich's ataxia were investigated for the GAA trinucleotide repeat expansion recently found within the gene X25 on chromosome 9. All 56 were found to be homozygous for the expansion, with all but two patients having alleles of differing sizes. The expansion size ranged from 2 to 5 kb, with normal alleles around 1.5 kb. Sizing of the single copy of the expansion in eight sets of parents revealed marked instability in the transmission of the expansion, with both increases and decreases in allele size seen. In Friedreich's ataxia patients there was a significant inverse correlation seen between the average of the two expansions sizes and age of onset of symptoms. The GAA repeat expansion was found in the homozygous state in atypical cases of Friedreich's ataxia, such as older age of onset, preservation of lower limb reflexes and cardiac presentations. In three families the father had onset of spinocerebellar ataxia as an adult, and in two the possibility of partial expression in heterozygote carrier fathers has been raised. More importantly, the history of an ataxic syndrome in a parent does not exclude the diagnosis of Friedreich's ataxia in the offspring, and tests for the expansion should be carried out. The third family with an affected father conforms to previously described 'pseudodominant' inheritance.

Recent progress in molecular mechanisms of leukemogenesis: the cyclin-dependent kinase 4-inhibitor gene in human leukemias

In order to clarify the significance of p16 gene (CDKN2) inactivation and its disease specificity among hematopoietic tumors, configurations of the p16 gene as well as those of the adjacent p15 and interferon alpha (IFN alpha) genes were examined in primary hematopoietic tumors. Loss of the p16 gene is frequent in and highly specific to lymphoid tumors among hematopoietic tumors. Gene deletions but not minute mutations should be the predominant mechanism of p16 gene inactivation in these types of tumors. The p16 gene is most frequently deleted among the p16, p15 and IFN alpha genes and thus should be the target of deletions in this locus. Deletions of the p16 gene were frequently observed in tumors carrying chromosome 9p abnormalities while a significant number of cases showed loss of the p16 gene without chromosome 9p abnormalities. So far inactivation of p53 and Rb tumor suppressors have also been found in lymphoid tumors. In our study, we detected homozygous deletions of p16 gene in 20%, loss of Rb protein in 28%, and p53 gene alterations in 8% of lymphoid tumors. Notably, 44% of lymphoid tumors showed inactivation of at least one of the three tumor suppressors, suggesting these tumor suppressors are important for lymphoid tumorigenesis. Inactivations of these tumor suppressors should independently occur in development of lymphoid tumors.

Gene locus for autosomal recessive distal myopathy with rimmed vacuoles maps to chromosome 9

Distal myopathy with rimmed vacuoles is an autosomal recessive muscular disorder, characterized clinically by weakness of the distal muscles in the lower limbs in early adulthood. Recently, the gene locus for familial vacuolar myopathy with autosomal recessive inheritance (hereditary inclusion body myopathy) was mapped to chromosome 9 by genome-wide linkage analysis of nine Persian-Jewish families. Since both disease conditions share similar clinical, genetic, and histopathological features, we analyzed seven families with distal myopathy with rimmed vacuoles using ten microsatellite markers within the region of the hereditary inclusion body myopathy locus. Significantly high cumulative pairwise lod scores were obtained with three markers: D9S248 (Z(max) = 5.90 at theta = 0), D9S43 (Z(max) = 5.25 at theta = 0), and D9S50 (Z(max) = 4.23 at theta = 0). Detection of obligate recombination events as well as multipoint linkage analysis revealed that the most likely location of the distal myopathy with rimmed vacuoles gene is in a 23.3-cM interval defined by D9S319 and D9S276 on chromosome 9. The results raise the possibility that distal myopathy with rimmed vacuoles and hereditary inclusion body myopathy in Persian Jews are allelic diseases.

Molecular cytogenetic analysis of buccal cells and lymphocytes from benzene-exposed workers

Benzene is a well-characterized human carcinogen and clastogen still present in both the occupational and general environment. However, the levels of benzene encountered today are, in most cases, relatively low and new methods, more specific and sensitive than classical cytogenetics, are probably needed to assess if current benzene exposures pose a genotoxic risk to human health. Bearing in mind the leukaemogenic action of benzene, blood lymphocytes appear to be a suitable cell system for biomonitoring studies. Buccal epithelium is an alternative source of tissue for monitoring human exposure to inhaled occupational and environmental genotoxicants. New molecular cytogenetic techniques allowing us to specifically study clastogenic or aneugenic events in human cells may provide the additional sensitivity required. In the present study, fluorescence in situ hybridization was used to examine the content of micronuclei (MN) (using the pan-centromeric DNA probe SO-alphaAllCen) in lymphocytes and buccal cells and to detect numerical abnormalities of chromosome 9 (using a chromosome 9 centromere-specific alphoid DNA probe) in buccal cells from a population occupationally exposed to benzene in an Estonian petrochemical plant. Age-matched Estonian volunteers were used as a control group. Individual benzene exposure levels were estimated to be around 1 p.p.m. (8 h time-weighted average). No increases in the frequency of total MN, MN harbouring whole chromosomes or acentric chromosomal fragments or chromosome 9 numerical abnormalities were detected in relation to benzene exposure in the present study. The lack of positive results was consistent in both buccal cells and lymphocytes, indicating that the benzene exposure levels encountered did not induce detectable clastogenic or aneugenic effects in the exposed workers. Other variables and confounding factors, such as age, smoking or alcohol consumption, did not influence any of the multiple cytogenetic biomarkers analysed.

Variant complex translocations involving chromosomes 1, 9, 9, 15 and 17 in acute promyelocytic leukemia without RAR alpha/PML gene fusion rearrangement

Acute promyelocytic leukemia (APL;M3) is specifically characterized by a predominance of malignant promyelocytes having atypical reciprocal translocation involving chromosome 15 and 17 [t(15;17)(q22;q11)] resulting in the fusion of retinoic acid receptor alpha (RAR alpha) on chromosome 17 and the putative transcription factor gene PML, ie the translocation generates two fusion transcripts, PML/RAR alpha and RAR alpha/PML. We describe a patient with clinical and morphologic characteristics of atypical APL but with a previously undescribed variant translocation. A 35-year-old Hispanic having atypical APL was referred for cytogenetic evaluation. The cytogenetic findings with GTG-banding coupled with FISH analysis revealed the following karyotype: 46,XX,der(9)t(1;9)(q25;q34)der(9)t(9;?)(q34;?), t(15;17)(q22;q11)ish. der(9)t(1;9)(q25;q34)(WCP1+,WCP9+),t(9;17;15)(q34;q11;q22) (WCP9+,WCP15+,PML+;WCP17+,RAR alpha +;WCP15+,WCP17+,PML-)[20]/46,XX[5]. The chromosome 17q was translocated to the chromosome 15q. However, chromosome 15q including the PML gene normally translocating to 17q and creating the RAR alpha/PML fusion gene, translocated to chromosome 9q. Does this patient have another subset of APL? Or is the genetics of APL different in cases with variant translocations as opposed to those with atypical t(15;17) translocation, though in the majority of the cases their clinical presentation remains the same.

Which compartments are involved in Philadelphia-chromosome positive chronic myeloid leukaemia? An answer at the single cell level by combining May-Grünwald-Giemsa staining and fluorescence in situ hybridization techniques

Chronic myeloid leukaemia (CML) is believed to represent a stem cell disorder involving all three cell lineages. The typical chromosomal aberration, the Philadelphia chromosome, is the translocation (9;22)(q34;q11). Several studies with cytogenetics, fluorescence in situ hybridization (FISH), or polymerase chain reaction have investigated the presence of the t(9;22) in different cell compartments. However, questions still remain. In six cases of CML we combined the standard May-Grünwald-Giemsa staining with FISH at the single-cell level and were able to demonstrate that not only all maturation stages of granulopoiesis, erythropoiesis, and megakaryocytes, but also plasma cells, eosinophils, basophils and monocytes carried the Philadelphia chromosome in 53-98% of samples. Using immunological identification of single cells we were able to demonstrate that the t(9;22) is detectable in 34% of CD3-positive T lymphocytes, in 32% of CD19-positive B lymphocytes, and in 82% of CD34-positive precursor cells. The results give new insight into the biology of CML and may have implications for future therapeutic strategies.

Clinical manifestations in 105 persons with nevoid basal cell carcinoma syndrome

Nevoid basal cell carcinoma syndrome (NBCC; Gorlin syndrome), an autosomal dominant disorder linked to 9q22.3-q31, and caused by mutations in PTC, the human homologue of the Drosophila patched gene, comprises multiple basal cell carcinomas, keratocysts of the jaw, palmar/plantar pits, spine and rib anomalies and calcification of the falx cerebri. We reviewed the findings on 105 affected individuals examined at the NIH since 1985. The data included 48 males and 57 females ranging in age from 4 months to 87 years. Eighty percent of whites (71/90) and 38% (5/13) of African-Americans had at least one basal cell carcinoma (BCC), with the first tumor occurring at a mean age of 23 (median 20) years and 21 (median 20) years, respectively. Excluding individuals exposed to radiation therapy, the number of BCCs ranged from 1 to > 1,000 (median 8) and 1 to 3 (median 2), respectively, in the 2 groups. Jaw cysts occurred in 78/105 (74%) with the first tumor occurring in 80% by the age of 20 years. The number of total jaw cysts ranged from 1 to 28 (median 3). Palmar pits and plantar pits were seen in 87%. Ovarian fibromas were diagnosed by ultrasound in 9/52 (17%) at a mean age of 30 years. Medulloblastoma occurred in 4 patients at a mean age of 2.3 years. Three patients had cleft lip or palate. Physical findings include "coarse face" in 54%, relative macrocephaly in 50%, hypertelorism in 42%, frontal bossing in 27%, pectus deformity in 13%, and Sprengel deformity in 11%. Important radiological signs included calcification of the falx cerebri in 65%, of the tentorium cerebelli in 20%, bridged sella in 68%, bifid ribs in 26%, hemivertebrae in 15%, fusion of the vertebral bodies in 10%, and flame shaped lucencies of the phalanges, metacarpal, and carpal bones of the hands in 30%. Several traits previously considered components of the syndrome (including short fourth metacarpal, scoliosis, cervical ribs and spina bifida occulta) were not found to be significantly increased in the affected individuals. This study delineates the frequency of the clinical and radiological anomalies in NBCC in a large population of US patients and discusses guidelines for diagnosis and management.

Cloning and chromosomal mapping of four putative novel human G-protein-coupled receptor genes

We report the discovery of four novel human putative G-protein-coupled receptor (GPCR) genes. Gene GPR20 was isolated by amplifying genomic DNA with oligos based on the opioid and somatostatin related receptor genes and subsequent screening of a genomic library. Also, using our customized search procedure of a database of expressed sequence tags (dbEST), cDNA sequences that partially encoded novel GPCRs were identified. These cDNA fragments were obtained and used to screen a genomic library to isolate the full-length coding region of the genes. This resulted in the isolation of genes GPR21, GPR22 and GPR23. The four encoded receptors share significant identity to each other and to other members of the receptor family. Northern blot analysis revealed expression of GPR20 and GPR22 in several human brain regions while GPR20 expression was detected also in liver. Fluorescence in situ hybridization (FISH) was used to map GPR20 to chromosome 8q, region 24.3-24.2, GPR21 to chromosome 9, region q33, GPR22 to chromosome 7, region q22-q31.1, and GPR23 to chromosome X, region q13-q21.1.

Frequent and selective methylation of p15 and deletion of both p15 and p16 in T-cell acute lymphoblastic leukemia

Frequent deletion of chromosome 9p21 in many cancers has suggested the presence of tumor suppressor genes in this region. Two genes mapping to 9p21, p15 and p16, encode inhibitors for cyclin-dependent kinases 4 and 6. We recently found that in T-cell acute lymphoblastic leukemia (T-ALL), both the p15 and p16 genes are deleted at a high frequency, with p16 gene deletion occurring slightly more frequently than p15 gene deletion. We now show that in addition to deletion, the p15 gene is preferentially hypermethylated at a 5' CpG island, which has been shown previously to be associated with loss of transcription of this gene. The p15 gene was methylated in 38% (17 of 45) of T-ALL patients at diagnosis and in 22% (7 of 32) of patients at relapse. On the other hand, methylation of the p16 gene was a rare event, occurring in 4% (2 of 49) of patients at diagnosis and in none (0 of 30) at relapse. The overall rates of alteration occurring in at least one allele of the p15 gene is 84% at diagnosis and 88% at relapse. These rates are as high as, if not greater than, those for the p16 gene (80% at diagnosis and 74% at relapse). In fact, such alterations involve both alleles in the majority of samples: 76% for p15 and 67% for p16 at diagnosis. All together, more than one-half (56%) of T-ALL samples harbor alterations in both alleles of both p15 and p16. These results lend strong support for a role of both p15 and p16 as tumor suppressors in T-ALL.

Cytogenetics adds independent prognostic information in adults with acute lymphoblastic leukaemia on MRC trial UKALL XA. MRC Adult Leukaemia Working Party

Cytogenetic classification of 350 adults with acute lymphoblastic leukaemia on MRC UKALL XA trial showed the following statistically significant associations: t(9;22) (11%) increased with increasing age and leucocyte counts (WBC) and most had a C/pre-B immunophenotype. t(4;11) (3%) was associated with higher WBCs, increasing age and null immunophenotype. Other abnormalities of 11q (abn11q) (4%) were associated with male sex and T-cell ALL. High hyperdiploidy (7%) and abn9p (5%) decreased with increasing WBC. High hyperdiploid patients were younger and tended to have C/pre-B ALL. Triploidy/tetraploidy (3%) decreased and pseudodiploidy (11%) increased with increasing WBC. Cytogenetic classification was prognostically important (chi-square for heterogeneity of classification = 53.56; P < 0.0001) and added significance to age, sex and WBC. A poor prognosis for patients classed as t(9;22) (13% disease-free survival at 3 years), as t(4;11) 24% at 3 years) and hypodiploid (11% at 3 years), and good prognosis for abn12p (4% of subjects) and high hyperdiploidy (74% and 59% at 3 years respectively) were statistically significant, but the 54% 3-year disease-free survival for patients with t(1;19) was not. The prognosis of patients classed as t(9;22) was independent of other single variables. Abn12p, abnormalities of 11q (including t(4;11) cases) and hypodiploidy added prognostic significance to all other variables combined.