Fragment length analysis screening for detection of CEBPA mutations in intermediate-risk karyotype acute myeloid leukemia.

During last years, molecular markers have been increased as prognostic factors routinely screened in acute myeloid leukemia (AML). Recently, an increasing interest has been reported in introducing to clinical practice screening for mutations in the CCAAT/enhancer-binding protein α (CEBPA) gene in AML, as it seems to be a good prognostic factor. However, there is no reliable established method for assessing CEBPA mutations during the diagnostic work-up of AMLs. We describe here a straightforward and reliable fragment analysis method based in PCR capillary electrophoresis (PCR-CE) for screening of CEBPA mutations; moreover, we present the results obtained in 151 intermediate-risk karyotype AML patients (aged 16-80 years). The method gave a specificity of 100% and sensitivity of 93% with a lower detection limit of 1-5% for CEBPA mutations. The series found 19 mutations and four polymorphisms in 12 patients, seven of whom (58%) presented two mutations. The overall frequency of CEBPA mutations in AML was 8% (n = 12). CEBPA mutations showed no coincidence with FLT3-ITD or NPM1 mutations. CEBPA mutation predicted better disease-free survival in the group of patients without FLT3-ITD, NPM, or both genes mutated (HR 3.6, IC 95%; 1.0-13.2, p = 0.05) and better overall survival in patients younger than 65 of this group without molecular markers (HR 4.0, IC 95%; 1.0-17.4, p = 0.05). In conclusion, the fragment analysis method based in PCR-CE is a rapid, specific, and sensitive method for CEBPA mutation screening and our results confirm that CEBPA mutations can identify a subgroup of patients with favorable prognosis in AML with intermediate-risk karyotype.

Analysis of SNP rs16754 of WT1 gene in a series of de novo acute myeloid leukemia patients.

The single nucleotide polymorphism (SNP) rs16754 of the WT1 gene has been previously described as a possible prognostic marker in normal karyotype acute myeloid leukemia (AML) patients. Nevertheless, the findings in this field are not always reproducible in different series. One hundred and seventy-five adult de novo AML patients were screened with two different methods for the detection of SNP rs16754: high-resolution melting (HRM) and FRET hybridization probes. Direct sequencing was used to validate both techniques. The SNP was detected in 52 out of 175 patients (30 %), both by HRM and hybridization probes. Direct sequencing confirmed that every positive sample in the screening methods had a variation in the DNA sequence. Patients with the wild-type genotype (WT1(AA)) for the SNP rs16754 were significantly younger than those with the heterozygous WT1(AG) genotype. No other difference was observed for baseline characteristic or outcome between patients with or without the SNP. Both techniques are equally reliable and reproducible as screening methods for the detection of the SNP rs16754, allowing for the selection of those samples that will need to be sequenced. We were unable to confirm the suggested favorable outcome of SNP rs16754 in de novo AML.

Risk-adapted treatment of acute promyelocytic leukemia with all-trans retinoic acid and anthracycline monochemotherapy: long-term outcome of the LPA 99 multicenter study by the PETHEMA Group.

A previous report of the Programa de Estudio y Tratamiento de las Hemopatías Malignas (PETHEMA) Group showed that a risk-adapted strategy combining all-trans retinoic acid (ATRA) and anthracycline monochemotherapy for induction and consolidation in newly diagnosed acute promyelocytic leukemia results in an improved outcome. Here we analyze treatment outcome of an enlarged series of patients who have been followed up for a median of 65 months. From November 1999 through July 2005 (LPA99 trial), 560 patients received induction therapy with ATRA plus idarubicin. Patients achieving complete remission received 3 courses of consolidation followed by maintenance with ATRA and low-dose chemotherapy. The 5-year cumulative incidence of relapse and disease-free survival were 11% and 84%, respectively. These results compare favorably with those obtained in the previous LPA96 study (P = .019 and P = .04, respectively). This updated analysis confirms the high antileukemic efficacy, low toxicity, and high degree of compliance of a risk-adapted strategy combining ATRA and anthracycline monochemotherapy for consolidation therapy.

High-resolution melting analysis for rapid screening of BRCA1 and BRCA2 Spanish mutations.

The majority of BRCA1 and BRCA2 mutation detection procedures include screening methods, all of which are time-consuming. High-resolution melting (HRM) is a promising pre-screening method of gene scanning that combines simplicity and rapid identification of genetic variants. We evaluated HRM in the screening of BRCA1/2 Spanish mutations. We studied 40 BRCA1 and 47 BRCA2 DNA samples with different Spanish mutations. We included a group of 20 unknown DNAs from patients with sporadic breast cancer (BC). The assay was performed with the LightCycler 480 Instrument (Roche). The HRM discriminates all the BRCA1/2 Spanish mutations studied from wild-type DNA. Besides, 54 out of 87 mutations were clearly differentiated from each other. In sporadic BC 11 polymorphisms and three unclassified variants were found in both genes. HRM is a valuable method for rapid screening of BRCA1/2 Spanish mutations and is capable of differentiating new genetic variants in PCR products.

Minimal residual disease detection in acute myeloid leukemia by mutant nucleophosmin (NPM1): comparison with WT1 gene expression.

BACKGROUND: Molecular analysis of minimal residual disease is only applicable in acute myeloblastic leukemia (AML) patients with genetic markers (20-30%). This study analyzes the feasibility of the real-time quantitative polymerase chain reaction (RQ-PCR) assay to detect mutant nucleophosmin (NPM1) during follow-up in AML patients. Moreover, we compare the NPM1 results with those of WT1 expression to MRD assessment. METHODS: The study includes 97 samples from 24 AML patients with type A NPM1 mutation at diagnosis. MRD was evaluated simultaneous by RQ-PCR assay to detect NPM1-mutated and WT1 expression. RESULTS: The expression levels of WT1 and NPM1 in 93 paired samples showed a strong positive correlation (r=0.81; p<0.0001). However, the kinetics of disappearance were different, WT1 decreased rapidly after induction but maintained these residual levels after treatment in patients in complete remission, whereas NPM1 experienced a mild reduction after induction but was undetectable in long survivor patients. CONCLUSIONS: This study shows the feasibility of the RQ-PCR assay to monitor MRD in AML patients carrying NPM1 mutations and its advantage over RQ-PCR assay for WT1. Owing to NPM1-mutated is specific of leukemic cells and shows higher levels at presentation.

The GST deletions and NQO1*2 polymorphism confers interindividual variability of response to treatment in patients with acute myeloid leukemia.

Functional polymorphisms in the genes encoding detoxification enzymes could modify the response to treatment in acute myeloid leukemia and therefore affect the final clinical outcome. In the present study, we genotyped 153 patients diagnosed with de novo acute myeloid leukemia (AML) to clarify the influence of the genetic polymorphisms CYP1A1*2A, CYP3A4*1B, CYP2E1*5B, del{GSTT1}, del{GSTM1}, and NQO1*2 on disease outcome. The del{GSTM1} showed a higher frequency in females (62%) than in males (41%) (P=0.01). The number of functional NQO1 alleles influenced the response to induction therapy; 81% (55/68) NQO1-negative patients, 69% (28/41) heterozygous patients, and 27% (2/7) homozygous patients achieved complete remission (CR) (P=0.04). The presence of GST deletions was associated with a lower probability of disease-free survival (DFS) and this effect was more relevant in male patients. Males with del{GSTM1} showed a 28% DFS versus 57% DFS for undeleted GSTM1 (P=0.04). Similarly, males with undeleted GSTM1 and GSTT1 showed a 64% DFS versus 34% DFS for males with at least one GST deletion (P=0.05). This study suggests that the NQO1*2 polymorphism is relevant to the patient's response to induction therapy and that GST deletions influence treatment outcome after chemotherapy, especially in male patients.

The potential effect of gender in combination with common genetic polymorphisms of drug-metabolizing enzymes on the risk of developing acute leukemia.

BACKGROUND AND OBJECTIVES: We examined common polymorphisms in the genes for glutathione S-transferase (GST), cytochrome P450 (CYP), quinone oxoreductase (NQO1), methylene tetrahydrofolate reductase (MTHFR), and thymidylate synthetase (TYMS) and the role of gender associated with the susceptibility to de novo acute leukemia (AL). DESIGN AND METHODS: We conducted a case-control study analyzing the prevalence of the polymorphisms CYP1A1*2A, CYP2E1*5B, CYP3A4*1B, del{GSTT1}, del{GSTM1}, NQO1*2, MTHFR C6777, and TYMS 2R/3R in 443 patients with AL [302 with acute myeloblastic leukemia (AML) and 141 with acute lymphoblastic leukemia (ALL)] and 454 control volunteers, using polymerase chain reaction (PCR)-based methods. RESULTS: We found a higher incidence of del{GSTT1} in patients with AML than among controls (25.6% vs. 13.7%, OR=2.2, p<0.001) and a higher incidence of NQO1*2 homozygosity (NQO1*2hom.) in males with the M3 FAB subtype than in control males (8.6% vs. 2.2%, OR=4.9, p=0.02). The del{GSTT1} and NQO1*2hom. polymorphisms increased the risk of ALL (OR=2.2 and 3.0, p=0.001 and 0.003, respectively). The higher risk conferred by NQO1*2hom. and del{GSTT1} mainly affected males (OR=6.1 and 2.4; p=0.002 and 0.005, respectively). INTERPRETATION AND CONCLUSIONS: Males harboring NQO1*2hom. and del{GSTT1} polymorphisms showed a higher risk than females of developing AL. Thus, gender might influence the risk of AL associated with these genetic polymorphisms.

MLL amplification in acute myeloid leukemia.

The chromosomal alterations at 11q23 that involve the mixed-lineage leukemia gene (MLL, HTRX1, HRX, ALL1) are one of the most common cytogenetic abnormalities in acute leukemia and have been associated with a poor prognosis. Given that not all MLL alterations are seen under conventional cytogenetics or fluorescence in situ hybridization (FISH), it is very important to use molecular techniques to determine the cause of alteration. In this study, we describe two cases of AML in which FISH analysis showed a high-level 11q23 amplification, to confirm if this overexpression may be accompanied by partial tandem duplication of the MLL gene (MLL-PTD). Both patients showed complex karyotype and an unfavorable clinical course. The 11q23 region characterization included conventional cytogenetics, FISH, and comparative genomic hybridization analysis to study the expression patterns of several oncogenes located within the amplified region and detection of partial tandem duplication of the MLL gene by reverse-transcription polymerase chain reaction (RT-PCR) and sequencing. MLL-PTD were detected in the two patients. Moreover, patient 1 showed amplification of the MLL flanking region. Our data suggest that molecular methods such as RT-PCR or sequencing should be used to detect MLL alterations, and that amplification of MLL locus may be extended to its flanking region.

Treatment with all-trans retinoic acid and anthracycline monochemotherapy for children with acute promyelocytic leukemia: a multicenter study by the PETHEMA Group.

PURPOSE: To analyze the simultaneous combination of all-trans retinoic acid (ATRA) and anthracycline monochemotherapy for children with acute promyelocytic leukemia (APL). PATIENTS AND METHODS: Since November 1996, 66 children (younger than 18 years) with genetically proven APL received induction therapy with ATRA and idarubicin. Consolidation therapy consisted of three courses of anthracycline monochemotherapy. After November 1999, patients with intermediate and high risk of relapse received consolidation therapy with ATRA and slightly reinforced doses of idarubicin. Maintenance therapy consisted of ATRA and low-dose mercaptopurine and methotrexate. RESULTS: Thirty-nine girls (59%) and 27 boys (41%) were included in this study. The WBC count at presentation was more than 10 x 10(9)/L in 26 patients (39%). Sixty-one children (92%) achieved complete remission (CR). Early deaths from hemorrhage and retinoic acid syndrome occurred in three patients and two patients, respectively. Toxicity was manageable during consolidation and maintenance therapy. No deaths in CR, clinical cardiomyotoxicity, or secondary malignancy occurred. Two patients had molecular persistence at the end of consolidation. Three clinical relapses and two molecular relapses were also observed. Apart from one molecular relapse, all these events occurred among children with hyperleukocytosis. The 5-year cumulative incidence of relapse was 17%, whereas disease-free and overall survival rates were 82% and 87%, respectively. CONCLUSION: A high incidence of hyperleukocytosis in children with APL was confirmed. Besides low toxicity and a high degree of compliance, a risk-adapted therapy combining ATRA and anthracycline monochemotherapy showed an antileukemic efficacy comparable to those previously reported with other chemotherapy combinations in children.

Influence of genetic polymorphisms on the risk of developing leukemia and on disease progression.

BACKGROUND: Recent studies have provided evidence that common genetic variations with low penetrance could account for a proportion of leukemia and could also influence disease outcome, although the results obtained are still controversial. MATERIAL AND METHODS: We reviewed 54 recent reports focused on the contribution of genetic polymorphisms to the risk of developing leukemia and to disease progression. The polymorphisms of genes encoding drug-metabolising enzymes (CYP family, NQO1, GSTT1, GSTM1, GSTP1), enzymes involved in folate metabolism (MTHFR, TYMS, SHMT1, MTRR), and DNA repair enzymes (XPD, XPG, RAD51, XRCC1, XRCC3, CHEK2, ATM) were considered in the review. RESULTS: There was a good agreement on the influence of NQO1*2 polymorphism and those of the enzymes involved in DNA repair with the increased risk of therapy-related leukemia/myelodysplastic syndrome. Most studies found a strong association between the polymorphisms MTHFR, C677T or A1298C, and NQO1*2 or *3 and the risk of acute lymphoblastic leukemia (ALL). In addition, most of the studies reported an association between GSTT1 deletions and an increased risk of de novo acute myeloid leukemia. In ALL, polymorphisms in the genes of folate metabolism are associated with poor prognosis, and the 3R3R TYMS polymorphism in particular is associated with methotrexate resistance. CONCLUSION: The reports reviewed support the hypothesis that several low-penetrance genes with multiplicative effects together with dietary effects, ambient exposition, and individual immune system responses, may account for the risk of leukaemia.

High-level amplification of the RUNX1 gene in two cases of childhood acute lymphoblastic leukemia.

The RUNX1 (alias AML1) gene is involved in several patterns of chromosomal translocations and rearrangements associated with human acute leukemia. Often, multiple signals for AML1 have been observed in childhood acute lymphoblastic leukemia (ALL) due to frequent polysomy of chromosome 21 in this leukemia. Additionally, high-level amplification of AML1, in the absence of polysomy of chromosome 21, has been reported in childhood ALL. We report two new cases of childhood ALL, without a ETV6/RUNX1 (alias TEL/AML1) rearrangement, showing high-level amplification of the AML1 gene detected by fluorescence in situ hybridization and comparative genomic hybridization analysis. The first case was an 11-year-old girl with 7-12 signals for AML1 in nearly 84% of the cells, and the loss of a TEL allele. In the second patient, a 6-year-old girl, multiple copies of the AML1 gene were also observed in 99% of the cells, although no deletion of TEL was found. The similarity in the clinicobiologic features of all the cases with this abnormality points to an emerging molecular cytogenetic subgroup of B-cell precursor ALL and suggests a possible dosage effect of AML1 in the pathogenesis of leukemia.

A t(17;20)(q21;q12) masking a variant t(15;17)(q22;q21) in a patient with acute promyelocytic leukemia.

Acute promyelocytic leukemia (APL) is genetically characterized by a reciprocal translocation between chromosomes 15 and 17, the t(15;17)(q22;q21), which results in the fusion gene PML/RARA. A small proportion of patients with APL have complex or simple variants of this translocation. We report the case of a 31-year-old woman with APL (FAB-M3 classical form) carrying an apparently balanced translocation t(17;20)(q21;q12) masking a t(15;17)(q22;q21) confirmed by fluorescence in situ hybridization (FISH) and molecular studies. The patient was treated with an all-trans-retinoic acid (ATRA) plus anthracycline-based protocol and achieved complete remission, with no recurrence to date. These results illustrate the usefulness of combining cytogenetics, FISH, and reverse transcription-polymerase chain reaction (RT-PCR) methods to evidence the PML/RARA fusion gene in cases with morphologic suspicion of APL with variant or cryptic t(15;17).

Molecular detection of Spanish deltabeta-thalassemia associated with beta-thalassemia identified during prenatal diagnosis.

BACKGROUND: beta-Thalassemia is one of the most common single gene disorders and is widely distributed in the Mediterranean region. The deltabeta-thalassemias are a rare group of disorders, however in Spain the Spanish deltabeta0 thalassemia that removes 114 kb of beta-globin cluster is quite frequent. METHODS: To establish a molecular diagnosis of beta-thalassemia in a second-trimester fetus from a couple who are beta-thalassemia carriers, a rapid real-time PCR method was performed to detect major mutations prevalent in people of the Mediterranean basin (IVS I-1, IVS I-6, IVS I-110, CD-6, CD-37, and CD-39). The Spanish deltabeta0 deletion was detected using PCR with deletion-specific primers. RESULTS: The father was diagnosed as a carrier for the IVSI-6 (T>C) mutation and the mother as carrier for the Spanish deltabeta0 deletion. The fetus was a compound heterozygote for both those mutations. The phenotype of compound heterozygosity for deltabeta/beta-thalassemia can range from mild thalassemia intermedia to thalassemia major. After confirming these results in the DNA from amniocentesis obtained at the 20th week of gestation, the couple decided to terminate the pregnancy. CONCLUSIONS: This paper reports the first molecular characterization of Spanishdeltabeta0-thalassemia associated with beta-thalassemia IVSI-6, and confirms the importance of prenatal genetic testing for single gene disorder such as beta-thalassemia.

Study of the S427G polymorphism and of MYBL2 variants in patients with acute myeloid leukemia.

Dysregulation of MYBL2 has been associated to tumorigenesis and the S427G polymorphism could induce partial inactivation of MYBL2, associating it with cancer risk. It has previously been shown that MYBL2 was over-expressed in some acute myeloid leukemias (AML), portending poor prognosis. However, to date no studies have investigated the S427G or other genetic variants of MYBL2 in AML. This study analyzed the S427G in 197 AML patients and 179 controls and screened the MYBL2 sequence in patients. In contrast to other studies in solid tumors, the S427G was not associated with the incidence of AML. This study detected four unannotated genetic alterations, of which the Q67X could be involved in MYBL2 dysfunction. Eight polymorphisms were identified, among which the rs73116571, located in a splicing region, was associated with higher incidence in AML and weaker MYBL2 expression, suggesting pre-disposition to AML. Additional functional studies should be performed to verify these genetic variations as possible targets in AML.

[BRCA1 and BRCA2 mutations in patients with familial breast cancer]. / Mutaciones en BRCA1 y BRCA2 en pacientes con historia familiar de cáncer de mama.

BACKGROUND AND OBJECTIVE: Familial breast (BC) and ovarian cancer (OC) has been associated with germ-line mutations in the cancer susceptibility genes BRCA1 and BRCA2. The mutational spectra vary depending on the study populations and the criteria applied for patient selection. The present study reports the mutations found in 48 families of the Valencian Community studied in the University Hospital La Fe of Valencia (Spain). PATIENTS AND METHOD: We analysed the BRCA1 and BRCA2 genes of 48 families (55 patients) with a family history of BC an/or OC. The method consists of DNA extraction, followed by a polymerase chain reaction, mutational analysis by heteroduplex formation in conformation-sensitive-gel electrophoresis and sequencing of the heteroduplex detected. RESULTS: We report eight different deleterious mutations, four in BRCA1 and four in BRCA2 and four unclassified variants (UV). We also identified the presence of the BRCA1 3889_3890delG mutation for the first time in the Spanish population. In BRCA2, we report two mutations not described in the breast cancer information care, the 5025delT which is completely new and the 9206_9219del14, which has already been described in Spanish population. We also describe for the first time the presence of UV 8038C>T in this gene. CONCLUSIONS: The mutational spectra and the presence of new mutations in the limited number of patients give support to the relevance of the study population in the mutational spectra.

Methylation of tumor suppressor genes is related with copy number aberrations in breast cancer.

This study investigates the relationship of promoter methylation in tumor suppressor genes with copy-number aberrations (CNA) and with tumor markers in breast cancer (BCs). The study includes 98 formalin fixed paraffin-embedded BCs in which promoter methylation of 24 tumour suppressor genes were assessed by Methylation-Specific Multiplex Ligation-dependent Probe Amplification (MS-MLPA), CNA of 20 BC related genes by MLPA and ER, PR, HER2, CK5/6, CK18, EGFR, Cadherin-E, P53, Ki-67 and PARP expression by immunohistochemistry (IHC). Cluster analysis classed BCs in two groups according to promoter methylation percentage: the highly-methylated group (16 BCs), containing mostly hyper-methylated genes, and the sparsely-methylated group (82 BCs) with hypo-methylated genes. ATM, CDKN2A, VHL, CHFR and CDKN2B showed the greatest differences in the mean methylation percentage between these groups. We found no relationship of the IHC parameters or pathological features with methylation status, except for Catherin-E (p = 0.008). However the highly methylated BCs showed higher CNA proportion than the sparsely methylated BCs (p < 0.001, OR = 1.62; IC 95% [1.26, 2.07]). CDC6, MAPT, MED1, PRMD14 and AURKA showed the major differences in the CNA percentage between the two groups, exceeding the 22%. Methylation in RASSF1, CASP8, DAPK1 and GSTP1 conferred the highest probability of harboring CNA. Our results show a new link between promoter methylation and CNA giving support to the importance of methylation events to establish new BCs subtypes. Our findings may be also of relevance in personalized therapy assessment, which could benefit the hyper methylated BC patients group.

Immunohistochemical, genetic and epigenetic profiles of hereditary and triple negative breast cancers. Relevance in personalized medicine.

This study aims to identify the profile of immunohistochemical (IHC) parameters, copy number aberrations (CNAs) and epigenetic alterations [promoter methylation (PM) and miR expression] related to hereditary (H) and triple negative (TN) breast cancer (BC). This profile could be of relevance for guiding tumor response to treatment with targeting therapy. The study comprises 278 formalin fixed paraffin-embedded BCs divided into two groups: H group, including 88 hereditary BC (HBC) and 190 non hereditary (NHBC), and TN group, containing 79 TNBC and 187 non TNBC (NTNBC). We assessed IHC parameters (Ki67, ER, PR, HER2, CK5/6, CK18 and Cadherin-E), CNA of 20 BC related genes, and PM of 24 tumor suppressor genes employing MLPA/MS-MLPA (MRC Holland, Amsterdam). MiR-4417, miR-423-3p, miR-590-5p and miR-187-3p expression was assessed by quantitative RT-PCR (Applied Biosystems). Binary logistic regression was applied to select the parameters that better differentiate the HBC or TN groups. For HBC we found that, ER expression, ERBB2 CNA and PM in RASSF1 and TIMP3 were associated with NHBC whereas; MYC and AURKA CNA were linked to HBC. For TNBC, we found that CDC6 CNA, GSTP1 and RASSF1 PM and miR-423-3p hyperexpression were characteristic of NTNBC, while MYC aberrations, BRCA1 hypermethylation and miR-590-5p and miR-4417 hyperexpression were more indicative of TNBC. The selected markers allow establishing BC subtypes, which are characterized by showing similar etiopathogenetic mechanisms, some of them being molecular targets for known drugs or possible molecular targets. These results could be the basis to implement a personalized therapy.

BRCA1 and BRCA2 mutations in males with familial breast and ovarian cancer syndrome. Results of a Spanish multicenter study.

Male breast cancer (MBC) is a rare disease that represents <1% of all breast cancers (BCs). We analyze the results of a multicenter study performed in Spanish familial MBC including family history of hereditary breast and ovarian cancer syndrome (HBOCS) and clinicopathological features. We also study the relationship between BRCA1/BRCA2 mutational status in male relatives affected with cancer (MAC) and, family history and tumor types. The study included 312 men index cases with family history of HBOCS and 61 MAC BRCA1/2 mutation-carriers. Family history, histological grade (HG), clinicopathological and immunohistochemistry data were collected. BRCA1/2 mutation analyses were performed by direct sequencing or screening methods and the large rearrangements by multiplex ligation dependent probe amplification. We found 49 mutation-carriers (15.7%), 95.9% with BRCA2 mutations. BRCA2 mutation-carriers were associated with families with at least one MBC and one BC in female (type II; p = 0.05). Strong association were found between the presence of pathogenic mutations in MBCs and the advanced HG (p = 0.003). c.658_659delTG, c.2808_2811delACAA, c.6275_6276delTT and c.9026_9030delATCAT were the most prevalent mutations. In 61 MAC we found 20 mutations in BRCA1 and 41 in BRCA2. For MAC we show that mutational status was differentially associated with family history (p = 0.018) and tumor type, being BRCA2 mutations linked with BC and prostatic cancer (p = 0.018). MBC caused by BRCA1/2 mutations define two types of MBCs. The most frequent caused by BRCA2 mutation linked to type II families and the rarest one attributed to BRCA1 mutation. Tumor associated with MAC suggest that only BRCA2 mutations have to do with a specific type of cancer (BC and prostatic cancer); but the linkage to tumors is questionable for BRCA1 mutations .

Identification of two atypical PML-RAR(alpha) transcripts in two patients with acute promyelocytic leukemia.

We identified two patients with atypical PML-RAR(alpha) rearrangements, 53 and 13 base pairs longer than the typical bcr1 transcript. Sequence analysis revealed a new PML breakpoint at the end of exon 7a in patient 1, and a PML exon 6 breakpoint in patient 2, with an insertion of 35 nucleotides of RAR(alpha) intron 2. Patient 1 did not express RAR(alpha)-PML and patient 2 showed the RAR(alpha)-PML transcript, which corresponded to the typical bcr1. These results emphasize on the relevance of the correct identification of atypical PML-RAR(alpha) rearrangements because of the potential implications in leukemogenesis, in the response to treatment, and for the correct monitoring of minimal residual disease.