Gain of multiple copies of the CBFB gene: a new genetic aberration in a case of granulocytic sarcoma

Granulocytic sarcomas (GS) are tumor masses of immature myeloid cells presenting at an extramedullary site, mainly the skin, bone, and lymph node. They are often associated with acute myeloid leukemia (AML) with monoblastic or myelomonocytic differentiation, including either AML M2 with t(8;21)(q22;q22) or AML M4Eo with inv(16)(p13q22). We present a case diagnosed with GS associated with AML M4 that presented a normal karyotype with conventional cytogenetic analysis. Although the myeloblasts did not show the inv(16)(p13q22) (CBFB/MYH11), a gain of multiple copies of the CBFB gene was detected with fluorescence in situ hybridization analysis. To our knowledge, no cases with this rare genetic anomaly have been previously described.     

A unique structural abnormality of chromosome 16 resulting in a CBF beta-MYH11 fusion transcript in a patient with acute myeloid leukemia, FAB M4

A 43-year-old female with a peripheral white cell count of 118.0 x 10(9)/L and 96% blasts was diagnosed with acute myeloid leukemia (AML), FAB M4. Cytogenetics, performed on a bone marrow sample, revealed the following abnormal karyotype: 46,XX,ins(16)(q22p13.1p13. 3). Fluorescence in situ hybridization (FISH) confirmed the inter-arm insertion using a probe for 16p. The result of this structural rearrangement was the fusion of CBF beta to MYH11 seen commonly in inv(16)(p13q22). The patient commenced high-dose intensive combination chemotherapy (big ICE; Idarubicin, Cytarabine, and Etopiside). Five days post chemotherapy, she developed febrile neutropenia. Despite broad spectrum intravenous antibiotics and antifungal therapy, the patient died at day nine post chemotherapy. This case demonstrates a previously unreported structural abnormality of chromosome 16 in a patient with AML M4, which represents a third mechanism to inv(16)(p13q22) and t(16;16)(p13q22) in producing the CBF beta-MYH11 fusion. CBF beta-MYH11 fusions masked by cryptic translocations at the cytogenetic level have been detected by FISH and PCR techniques. Due to the improved prognosis associated with CBF beta-MYH11 fusions compared to the standard risk group for AML, its detection remains important.     

急性髓系白血病细胞遗传学的分型诊断意义

为探讨细胞遗传学在急性髓系白血病（ＡＭＬ）分型诊断中的意义，回顾性分析了１６７例原发性初诊ＡＭＬ患者的核型与ＡＭＬ亚型之间的关系。结果表明：６７．７％的患者有克隆性染色体异常，ｔ（８；２１）、ｔ（１５；１７）、ｉｎｖ（１６）／ｄｅｌ（１６）分别与Ｍ２ｂ、Ｍ３、Ｍ４Ｅｏ特异性相关，１１号染色体异常常见于Ｍ４、Ｍ５。细胞遗传学可作为ＡＭＬ亚型的分型诊断手段之一。     

Deletion of CBFB in a patient with acute myelomonocytic leukemia (AML M4Eo) and inversion 16

Acute myelomonocytic leukemia with bone marrow eosinophilia (AML M4Eo) is a subtype of AML with distinct morphological features. Inversion (16)(p13.1q22), t(16;16)(p13.1;q22), and del(16)(q22) are nonrandom abnormalities associated with AML M4Eo and a favorable prognosis, compared with the standard risk group for AML. Deletions of the proximal region of the MYH11 gene located at 16p13.1 have been detected in about 20% of patients with inv(16), with an undetermined effect on patient survival. We present the case of a patient with AML M4Eo and inversion 16 with a distal deletion of the CBFB gene at 16q22 detected with fluorescence in situ hybridization. To our knowledge, only one previous report of a similar deletion has appeared in the literature.     

伴11号染色体异常的急性髓系白血病的临床和细胞遗传学研究

目的 研究11号染色体异常在急性髓系白血病中的发生率及与临床和预后的关系.方法 采用R带常规显带技术进行染色体检查,对356例急性髓系白血病患者的核型进行分析.结果 356例急性髓系白血病患者中检出11号染色体异常患者34例,占9.55%;其中20例(58.8%)涉及11q23,7例11p15易位(20.6%),5例-11(14.7%),其他少见的核型改变有:+11,t(11;14).11q23中,M4、M5占70%;且有10例同时合并有其他染色体异常.30例进行正规化疗的患者,13例缓解,缓解率低于同期急性髓系白血病的总缓解率(43.3% vs64.0%);伴11q23的急性髓系白血病的缓解率低于染色体正常的急性髓系白血病患者(45% vs67%);11q23伴其他染色体异常的缓解率低于伴单纯11q23者(30% vs60%).7例涉及11p15易位患者3例缓解,2例早期复发.5例-11患者缓解2例.结论 11q23是11号染色体异常中最为常见的核型改变,且多见于急性髓系白血病的M5型,并可能与急性单核细胞白血病的发病有关;伴11号染色体异常的急性髓系白血病患者预后较差.     

髓系白血病患者的临床和细胞遗传学研究

目的研究髓系白血病(myeloid leukemia,ML)患者细胞遗传学特点和相关临床表现及预后。方法采用骨髓细胞直接法和(或)不加植物血凝素的24h体外细胞培养法制备骨髓染色体。应用热变性姬姆萨显带技术为主、胰酶消化技术必要时补充,进行染色体核型分析。结果在578例髓系白血病中:急性髓系白血病(acute myeloid leuckemia,AML)420例,223例检出有克隆性染色体异常,占53.1%(223/420)。t(8;21)、t(15;17)、inv(16)、del(11)分别与M2b、M3、M4Eo、M5特异性相关。慢性髓系白血病(chronic myeloid leukemia,CML)158例,153例检出有克隆性染色体异常,占96.8%(153/158例)。t(9;22)与绝大多数CML及少部分M0、M1、M2特异性有关。本组髓系白血病中有18例(AML13例、CML5例)患者,占3.1%(18/578),其细胞遗传学检查未见克隆性染色体异常,与患者的临床表现、骨髓象形态学及免疫学的诊断不尽相同。为此我们应用了荧光原位杂交(fluorescence in situ hybridization,FISH)技术,其中15例结果完全符合临床和髓系白血病的血液学改变,同时也明显提高了临床的诊断率。结论染色体核型分析不但有助于髓系白血病的诊断和鉴别诊断,而且还是临床监测病情缓解和复发、判断疗效的重要指标。在染色体核型分析基础上选用合适的FISH技术,可对大多数髓系白血病患者作出精确的染色体分析。     

Clinical and cytogenetics studies on acute myeloid leukemia with abnormality of chromosome 11

OBJECTIVE: To investigate the incidence of chromosome 11 abnormality in acute myeloid leukemia and its relationship with the clinical aspects and prognosis. METHODS:Conventional cytogenetic analysis of R-band was used to detect the abnormalities of chromosome 11 in 356 acute myeloid leukemia patients. RESULTS: Thirty-four out of 356 patients (9.55%) had abnormalities of chromosome 11, of which 20 (58.8%) involved in 11q23, 7 (19.9%) had translocations involving 11p15, 5 (14.7%) had-11, and the rest had other abnormalities such as +11, and t(11;14). The incidence of 11q23 involvement in M4 and M5 was higher than other subtypes of acute myeloid leukemia (AML). Ten cases with 11q23 abnormality had additional cytogenetic aberrations. In 30 cases treated with chemotherapy, 13 cases acquired complete remission (CR). The CR rate was lower than that of whole cases of acute myeloid leukemia(34.3% versus 64.0%). The CR rate of AML with 11q23 abnormality was lower than that of AML with normal karyotype (25% versus 55.6%). In other 10 patients with additional chromosome aberrations, the CR rate was lower than that of AML with 11q23 alone. In 7 patients with translocations at 11p15, only 3 patients acquired CR, and 2 patients relapsed early. Only 2 patients acquired CR in 5 patients with-11. CONCLUSION: 11q23 was a frequent aberration in chromosome 11 anomaly, which was often detected in M4 and M5. It might be associated with the pathogenesis of acute monolytic leukemia. The patients with chromosome 11 anomaly had poorer prognosis.     

伴7号染色体异常的急性白血病32例分析

目的探讨7号染色体异常在急性白血病中的发生率及预后意义。方法采用R带常规显带技术进行染色体检查,对410例急性白血病患者的核型进行分析。结果410例急性白血病患者中检出7号染色体异常患者32例,占7.8%;其中-7/7q-19例(59.4%),t(7;11)3例(9.4%),其他为少见的7号染色体改变der(7), 7,t(2;7),t(5;7),t(7;9),t(7;8),dic(1;7)。-7/7q-中,急性髓细胞白血病12例,其中M0、M1、M2型的-7/7q-发生率高于其他类型急性髓细胞白血病。32例患者中20例同时有其他染色体异常,最常见的是t(9;22)伴-7, 8,-5。30例进行正规化疗的患者,11例缓解,缓解率低于同期急性白血病的总缓解率(36.7%vs65.8%);伴-7/7q-的急性髓细胞白血病的缓解率低于染色体正常的急性髓细胞白血病患者(25%vs55.6%);伴-7/7q-的急性淋巴细胞白血病的缓解率与染色体正常的急性淋巴细胞白血病患者无差异(57.1%vs77.8%),但缓解的4例急性淋巴细胞白血病患者均于短期内复发。伴其他7号染色体异常的11例患者仅4例缓解。结论-7/7q-是7号染色体异常中最为常见的核型改变,且多见于急性髓细胞白血病的M0、M1、M2型,并可能与急性白血病的发病有关;伴7号染色体异常的急性白血病患者预后较差。     

多探针荧光原位杂交检测急性髓系白血病常见细胞遗传学异常

目的:评价多探针荧光原位杂交(FISH)在检测急性髓系白血病(AML)常见细胞遗传学异常中的价值,探讨细胞遗传学异常与临床诊断、治疗、预后的关系。方法:采用针对AML/MDS的FISH多探针诊断系统,即以针对AML1/ETO融合基因、PML-RARα融合基因、CBFβ/MYH11融合基因、MLL基因、P53基因、Del(5q)、Del(7q)、Del(20q)8种DNA探针对40例患者进行多探针FISH检测,同时联合染色体核型、临床资料进行研究。结果:40例AML中,共22例多探针FISH检出了细胞遗传学改变,包括:AML1/ETO、PML-RARα、MLL基因断裂重排、Del(5q)、Del(7q)、P53基因缺失、8号染色体三体7种细胞遗传学异常。而常规染色体核型分析仅检出11例遗传学异常。多探针FISH与染色体核型分析的总阳性率分别为57.50%及27.50%。AML1/ETO、PML/RARα阳性者首次诱导化疗效果较理想;而Del(7q)、MLL基因断裂重排阳性、伴复杂细胞遗传学改变者可能预示不良预后。结论:FISH多探针诊断系统检测AML患者常见遗传学异常更省时、准确、高效,有利于完善白血病的分层诊断及指导临床个体化治疗。     

Banding and molecular cytogenetic studies detected a CBFB-MYH11 fusion gene that appeared as abnormal chromosomes 1 and 16 in a baby with acute myeloid leukemia FAB M4-Eo

The acute myeloid leukemia (AML) subtype M4Eo occurs in 5% of all AML cases and is usually associated with either an inv(16)(p13.1q22) or a t(16;16)(p13.1;q22) chromosomal abnormality. At the molecular level, these abnormalities generate a CBFB-MYH11 fusion gene. Patients with this genetic alteration are usually assigned to a low-risk group and thus receive standard chemotherapy. AML-M4Eo is rarely found in infants. We describe clinical, conventional banding, and molecular cytogenetic data for a 12-month-old baby with AML-M4Eo and a chimeric CBFB-MYH11 fusion gene masked by a novel rearrangement between chromosomes 1 and 16. This rearrangement characterizes a new type of inv(16)(p13.1q22) masked by a chromosome translocation.     

Acute myeloid leukemia with cryptic CBFB-MYH11 type D

A 77 year-old female was found with FAB M4Eo acute myeloid leukemia. Although CBFB-MYH11 mRNA was detected in RT-PCR, the conventional cytogenetic analysis failed to reveal inv(16). Fluorescence in situ hybridization (FISH) and the sequence analysis revealed a fusion between the exon 5 of CBFB and the exon 8 of MYH11, resulting in a minor variant fusion product previously reported as type D. In order to detect the cryptic inv(16) type D, both FISH and RT-PCR are required, and furthermore, the primers for the sequence analysis needs to be selected for the proper diagnosis.     

Chromosome 16 abnormalities associated with myeloid malignancies

Twenty-six patients who had cytogenetic analyses performed for myeloid malignancies at St. Vincent's Hospital over a 6-year period were found to have an inversion abnormality of chromosome 16 (25 patients) or t(16;16) (1 patient). Only 16 patients had all the features of M4Eo, while the other 10 patients had diagnoses of M2, M4, M5, RAEB, and RAEB-T; six of these had abnormal eosinophils. Thus, abnormal eosinophils were present in 22 of 26 patients (85%). Thirteen patients had additional cytogenetic abnormalities at diagnosis, the commonest being +8 in 5, del(7q) in 4, and +21 in 3. Twenty-three patients received chemotherapy and 20 (87%) achieved complete remission. The median survival of the treated group was 188 weeks with a 61% 2-year and 45% 5-year survival. No significant difference in survival was observed between those patients with a diagnosis of M4Eo and those with other diagnoses suggesting that it is the abnormality of chromosome 16 which confers an improved prognosis. Additional cytogenetic abnormalities present at diagnosis did not affect prognosis. CNS relapse was observed in only two patients (8%), thus indicating no increased incidence of this complication. This study supports the premise that a chromosome abnormality involving 16p13 and 16q22 defines a good prognosis subset of myeloid leukemia despite morphological variations.     

Comparative analysis of genes regulated in acute myelomonocytic leukemia with and without inv(16)(p13q22) using microarray techniques, real-time PCR, immunohistochemistry, and flow cytometry immunophenotyping.

Acute myeloid leukemia with inv(16)(p13q22), also known as M4Eo, is a distinct type of leukemia with characteristic clinicopathologic and cytogenetic features. Patients with M4Eo have monocytosis, high blast counts, and abnormal bone marrow eosinophils that contain large basophilic granules. The inv(16)(p13q22) or, less commonly, the t(16;16)(p13;q22) causes fusion of the CBFbeta gene at 16q22 and the MYH11 gene at 16p13, creating the novel chimeric protein CBFbeta-MYH11. To understand the underlying molecular mechanisms unique to M4Eo biology, we determined the gene expression profile of M4Eo cases by using cDNA and long oligonucleotide microarrays. Cases of acute myelomonocytic leukemia without CBFbeta-MYH11 (M4) acted as our control. We found that in the gene expression profile of M4Eo, NF-kappaB activators and inhibitors were upregulated and downregulated, respectively, suggesting that the NF-kappaB signaling pathway is activated at a higher level in M4Eo than in acute myelomonocytic leukemia M4. In addition, the gene expression profile of M4Eo indicates high cell proliferation and low apoptosis. We used real-time PCR, immunohistochemistry, and flow cytometry immunophenotyping to confirm some of our microarray data. These findings most likely represent the functional consequences of the abnormal chimeric protein CBFbeta-MYH11, which is unique to this disease, and suggest that NF-kappaB is a potential therapeutic target for treating M4Eo patients.