Kalliopi N. Manola

Isochromosome der(17)(q10)t(15;17) in Acute Promyelocytic Leukemia Resulting in an Additional Copy of the RARA-PML Fusion Gene: Report of 4 Cases and Review of the Literature

Isochromosome of the long arm of the derivative chromosome 17, originating from the translocation t(15;17) [ider(17)(q10)t(15;17) or ider(17q)] in acute promyelocytic leukemia (APL), is a rare chromosome aberration which has been associated with a poor prognosis. In the present study, we report on 4 male APL patients with ider(17q) and review the clinical, cytogenetic and molecular characteristics of all previously reported APL patients with ider(17q) in order to clarify the clinical features and outcome of these patients. The data presented in this study demonstrated that ider(17q), which resulted in an extra RARA-PML fusion gene, was more frequent in males than females (male/female ratio of 2.12/1), was associated with a rather low initial white blood cell count and did not confer an adverse prognosis in APL patients treated with all-trans-retinoic acid and chemotherapy. The most frequent additional chromosome change to ider(17q) was trisomy 8. Ider(17q) was observed in all subtypes of the PML-RARA fusion gene, but the frequency of the bcr1 subtype was increased. Cases of overrepresentation of the RARA-PML fusion gene and ider(17q) cases may help in elucidating the role of RARA-PML in leukemogenesis.

Jumping translocations in hematological malignancies: a cytogenetic study of five cases

Jumping translocations (JT) are rare cytogenetic aberrations in hematological malignancies that include unbalanced translocations involving a donor chromosome arm or chromosome segment that has fused to two or more different recipient chromosomes in different cell lines. We report five cases associated with different hematologic disorders and JT to contribute to the investigation of the origin, pathogenesis, and clinical significance of JT. These cases involve JT of 1q in a case of acute myeloblastic leukemia (AML)-M1, a case of Burkitt lymphoma, and a case of BCR/ABL-positive acute lymphoblastic leukemia, as well as a JT of 13q in a case of AML-M5, and a JT of 11q segment in a case of undifferentiated leukemia. To our knowledge, with regard to hematologic malignancies, this study presents the first case of JT associated with AML-M1, the first case of JT involving 13q as a donor chromosome, and the first report of JT involving a segment of 11q containing two copies of the MLL gene, jumping on to two recipient chromosomes in each cell line and resulting in six copies of the MLL gene. Our investigation suggests that JT may not contribute to the pathogenesis but rather to the progression of the disease, and it demonstrates that chromosome band 1q10 as a breakpoint of the donor chromosome 1q is also implicated in AML, not only in multiple myeloma as it has been known until now.

UGT1A1*28 Polymorphism in Chronic Lymphocytic Leukemia: The First Investigation of the Polymorphism in Disease Susceptibility and Its Specific Cytogenetic Abnormalities

Chronic lymphocytic leukemia (CLL) has been recently attributed to a combination of genetic predisposition and exposure to environmental factors. UDP-glucuronosyltransferase (UGT)1A1*28 is an inborn polymorphism that results in significant downregulation of uridine diphosphate glucuronyltransferase 1-1 (UGT1A1) activity, one of the most critical metabolizing enzymes involved in the detoxification of toxic substances, some of which contribute to CLL pathogenesis. Here, for the first time, we investigated the putative impact of UGT1A1*28 on CLL incidence and on the formation of the most common chromosomal abnormalities of CLL. UGT1A1*28 was investigated in 109 CLL patients and 108 healthy controls, and was associated with karyotypic and fluorescence in situ hybridization (FISH) results. A significant high frequency of the mutant genotype was observed in patients carrying abnormal FISH patterns, especially del(11q) and +12, which are CLL-specific abnormalities. We also observed a significant association between UGT1A1*28 and the intermediate to unfavorable cytogenetic CLL risk groups. No difference, though, was observed in genotypes between patients and controls. Therefore, we could suggest that UGT-deficient individuals may be at a greater risk for developing CLL-specific abnormalities. Our study might serve as a starting point to consider UGT1A1*28 polymorphism as one of the possible predisposing factors of CLL pathogenesis.

Association of A(313)G glutathione S-transferase P1 germline polymorphism with susceptibility to de novo myelodysplastic syndrome.

Abstract Models for the pathogenesis of myelodysplastic syndrome (MDS) imply the role of individual genetic variations in genes involved in detoxification mechanisms. GSTP1 enzyme plays a key role in the biotransformation of a variety of carcinogens. The corresponding gene is subject to a single nucleotide polymorphism (A313G) leading to abolished enzyme activity. In order to evaluate whether the GSTP1 polymorphism influences MDS susceptibility, we conducted a case–control study comprising 310 de novo patients and 370 healthy controls using a real-time polymerase chain reaction (PCR) genotyping method. The GSTP1 gene status was also evaluated in relation to patients’ characteristics and chromosomal abnormalities. A significantly higher incidence of the GSTP1 variant genotypes was observed in patients with MDS compared to controls (p < 0.0001). The results revealed increased frequencies of heterozygotes in patients younger than 60 years old and of homozygotes G/G in older patients (p = 0.007). Our results provide evidence for a pathogenetic role of the GSTP1 polymorphism in MDS risk, probably in an age-dependent manner.

Deletion of 5q as a rare abnormality in chronic lymphocytic leukemia

Deletions of the long arm of chromosome 5 [del(5q)] are frequent chromosome aberrations with known prognosis in myelodysplastic syndromes and acute myeloid leukemia (AML). However, in chronic lymphocytic leukemia (CLL), they are rare and have been reported only as karyotypic results without known prognosis. In the present study, we report a novel conventional and molecular cytogenetic study of two CLL patients carrying interstitial del(5q) in order to contribute to the identification of rare recurrent aberrations and their prognostic impact in CLL. Karyotypic and fluorescence in situ hybridization analysis that used probes for the most common aberrations of CLL demonstrated that del(5q) was the sole chromosome abnormality in both patients at the time of diagnosis. None of these patients had a history of exposure to chemotherapy or radiotherapy. Both patients had disease that was still staged as Binet A at 28 and 18 months after diagnosis, respectively, without receiving any therapy because of their good clinical condition. Therefore, it could be suggested that del(5q) may not be associated with an adverse prognosis in CLL and is not related with therapy-induced chromosome changes. Further studies are required to elucidate the prognostic value of these deletions in more CLL patients, which could be advisable for prognostic and therapeutic purposes, as well as to identify candidate genes that may potentially play a role in the pathogenesis of CLL.

Translocation (6;13)(p21;q14.1) as a rare nonrandom cytogenetic abnormality in chronic lymphocytic leukemia

Chronic lymphocytic leukemia (CLL) is associated with recurrent cytogenetic abnormalities that are important prognostic indicators and may influence treatment choices. Nonetheless, several chromosome abnormalities have not yet been completely determined, because of the low mitotic in vitro activity of B-CLL cells. Now, novel technologies such as stimulation of CLL cells with new B-cell mitogens have helped to overcome this problem. We present here a novel conventional and molecular cytogenetic study of a CLL patient with t(6;13)(p21;q14.1), a rare chromosomal aberration. The findings contribute to the identification of rare recurrent aberrations and of any prognostic effect in CLL that could be used for prognostic and therapeutic purposes. The present study demonstrates that t(6;13)(p21;q14.1) as a secondary event to the interstitial deletion in 13q14 region, resulting in the loss of RB1, is a rare but nonrandom abnormality in CLL, resistant to the current treatment CLL protocols with a rather favorable or intermediate prognosis but definitely not an adverse prognosis. Further studies in more CLL patients are required to delineate the prognostic value of t(6;13)(p21;q14.1) and to identify any candidate genes with potential role in the pathogenesis of the disease.

Association of C609T-Inborn Polymorphism of NAD(P)H: Quinone Oxidoreductase 1 with the Risk of Bronchopulmonary Dysplasia in Preterm Neonates

UNLABELLED Objectives In bronchopulmonary dysplasia (BPD), direct exposure to oxygen therapy can damage the pulmonary epithelium via oxidative stress. The NAD(P)H quinone oxidoreductase 1 (NQO1) enzyme detoxifies genotoxic products of oxidative stress. The corresponding gene is subject to an inactivating single-nucleotide polymorphism (C(609)T), which reduces detoxifying ability. The aim of this study was to investigate whether the C(609)T NQO1 inborn gene polymorphism is associated with an increased risk of BPD. Study Design Peripheral blood samples from 119 premature neonates ≤ 32 weeks of gestational age (42 BPD and 77 non-BPD) were used for DNA extraction. NQO1 genotyping was performed using the polymerase chain reaction-restriction fragment length polymorphism method. Results A significantly higher frequency of the NQO1 polymorphism was observed in BPD neonates compared with neonates without BPD. All neonates with ≤ 1,000 g birth weight who carried the mutant allele in heterozygous or homozygous state developed BPD. None of the BPD nonaffected group neonates with ≤ 1,000 g birth weight carried the NQO1 polymorphism. Conclusion The higher incidence of NQO1 mutants among BPD neonates as well as the presence of the mutant allele in all neonates with ≤ 1,000 g who developed BPD provided the first evidence for a possible pathogenetic role of the C(609)T polymorphism in BPD susceptibility due to the reduction or loss of NQO1 enzymatic activity.

The G516T CYP2B6 Germline Polymorphism Affects the Risk of Acute Myeloid Leukemia and Is Associated with Specific Chromosomal Abnormalities

The etiology of acute myeloid leukemia (AML) underlies the influence of genetic variants in candidate genes. The CYP2B6 enzyme detoxifies many genotoxic xenobiotics, protecting cells from oxidative damage. The CYP2B6 gene is subjected to a single-nucleotide polymorphism (G516T) with heterozygotes (GT) and homozygotes (TT) presenting decreased enzymatic activity. This case-control study aimed to investigate the association of CYP2B6 G516T polymorphism with the susceptibility of AML and its cytogenetic and clinical characteristics. Genotyping was performed on 619 AML patients and 430 healthy individuals using RCR-RFLP and a novel LightSNip assay. The major finding was a statistically higher frequency of the variant genotypes (GT and TT) in patients compared to the controls (GT:38.8% vs 29.8% and TT:9.3% vs 5.3% respectively) (p<0.001). More specifically, a significantly higher frequency of GT+TT genotypes in de novo AML patients (46.6%) and an immensely high frequency of TT in secondary AML (s-AML) (20.5%) were observed. The statistical analysis showed that the variant T allele was approximately 1.5-fold and 2.4-fold higher in de novo and s-AML respectively than controls. Concerning FAB subtypes, the T allele presented an almost 2-fold increased in AML-M2. Interestingly, a higher incidence of the TT genotype was observed in patients with abnormal karyotypes. In particular, positive correlations of the mutant allele were found in patients carrying specific chromosomal aberrations [-7/del(7q), -5/del(5q), +8, +21 or t(8;21)], complex or monosomal karyotypes. Finally, a strikingly higher frequency of TT genotype was also observed in patients stratified to the poor risk group. In conclusion, our results provide evidence for the involvement of the CYP2B6 polymorphism in AML susceptibility and suggest a possible role of the CYP2B6 genetic background on the development of specific chromosomal aberrations.

Association of various risk factors with chronic lymphocytic leukemia and its cytogenetic characteristics.

ABSTRACT This study aimed to investigate whether occupational and environmental exposures, lifestyle, family, and medical history are associated with chronic lymphocytic leukemia (CLL) risk and its chromosomal abnormalities. The study included 138 CLL cases and 141 age- and sex-matched controls. Information data were collected through in-person interviews from cases and controls. Cytogenetic analysis was performed on CLL bone marrow cells. Positive associations were found between CLL and cancer family history, smoking, pneumonia, and exposure to petroleum, metals, pesticides/chemical fertilizers, detergents, and medical radiation. Chromosome deletions of 11q and 13q were more frequent in patients exposed to pesticides and rubber, respectively. This study investigated for the first time specific risk factors in relation to CLL aberrations and presented positive correlations. Moreover, it indicates the possible involvement of specific occupational and lifestyle risk factors in the onset of CLL.

High frequency of NAD(P)H:quinone oxidoreductase 1 (NQO1) C609T germline polymorphism in MDS/AML with trisomy 8

The NQO1 C(609)T germline polymorphism resulting in a lowering of enzyme activity may confer susceptibility to MDS. To assess this association, we performed a case-control study including 330 Greek patients with de novo MDS and 416 healthy donors, using a Real-Time PCR genotyping method. Focusing on cytogenetic aberrations most commonly found in MDS, we retrospectively genotyped 566 MDS/AML patients carrying -5/del(5q), -7/del(7q), +8, del(20q) and -Y. The case-control analysis revealed no differences in NQO1 genotype distribution. Interestingly, a 6-fold increased frequency of the homozygous variant genotype was observed among patients with isolated trisomy 8 (p<0.0001), suggesting that null NQO1 activity may influence the occurrence of +8 in MDS/AML.