Childhood B-cell progenitor acute lymphoblastic leukemia presenting a three-way t(11;12;21)(q14;p13;q22) with a RUNX1 gene signal on chromosome 11

MYC-r with a non-IG partner concurrently with a cryptic t(12;21) in B-lymphoblastic leukemia: A case and prognostic significance

B-lymphoblastic leukemia (B-ALL) in children is characterized by recurrent chromosomal rearrangements that mostly have prognostic value. MYC rearrangements (MYC-r), typically associated with Burkitt lymphoma or mature B-cell neoplasms are infrequent in B-ALL. We report here a unique case of childhood B-ALL with concurrent MYC-r with a non-IG partner and a cryptic t(12;21). Leukemic cells had lymphoblastic morphology. Immunophenotypically, leukemic blasts were CD10 (+, slightly bright), CD15 (few +), CD19 (+), CD20 (+, partial), CD22 (+), CD34 (-), CD38 (+, slightly variably), CD45 (+, partial), cytoplasmic CD79a (+), HLA-DR (+), surface Ig (-), MPO (-), and TdT (+, partially). This immunophenotype was consistent with B-ALL. Cytogenetically, the karyotype was complex including a t(4;8)(q31;q24), and FISH analysis showed MYC-r, ETV6::RUNX1 and loss of ETV6 allele. The patient has been in complete remission for 11 years following the diagnosis. We reviewed cases of B-ALL with double leukemogenic alterations and MYC-r with non-IG partners to understand the clinical outcome in these rare patients.

Simultaneous involvement of 11q23 translocation resulting in chimeric MLL-AFF1 and a second translocation [t (9;21) (p13; p11.2)] in an infant acute lymphoblastic leukemia patient at relapse: A case report

RATIONALE

Three-way translocations occasionally occur in MLL-AFF1 fusion and other fusion gene. However, the complex chromosomal rearrangements in the study were the first report.

PATIENT CONCERNS

We present novel cryptic and complex chromosomal rearrangements [der (21) t (9; 21) (p13; p11.2)] in an infant patient with relapsed acute lymphoblastic leukemia (ALL).

DIAGNOSES

The diagnosis was based on morphologic, cytochemical, and immunophenotypic criteria proposed by the French-American-British Committee, and karyotype, fluorescence in situ hybridization, array comparative genomic hybridization.

INTERVENTIONS

The patient was given chemotherapy with standard protocol for ALL.

OUTCOMES

The patient had unfavorable prognostic outcome based on the cytogenetic and molecular cytogenetic markers. After short remission, the patient relapsed.

LESSONS

MLL-AFF1, resulting from t(4;11)(q21;q23), is regarded as the hallmark of infant t(4;11) pre-B/mixed B-ALL. It is associated with a dismal prognosis and the multiple-way translocation involving chromosomes 4, 11 and 11 may function as an enhancer.

Whole-Exome Sequencing of ETV6/RUNX1 in Four Childhood Acute Lymphoblastic Leukaemia Cases

Background:

ETV6/RUNX1 gene fusion is the most frequently seen chromosomal abnormality in childhood acute lymphobastic leukamia (ALL). However, additional genetic changes are known to be required for the development of this type of leukaemia. Therefore, we here aimed to assess the somatic mutational profile of four ALL cases carrying the ETV6/RUNX1 fusion gene using whole-exome sequencing.

Methods:

DNA was isolated from bone marrow samples using a QIAmp DNA Blood Mini kit and subsequently sequenced using the Illumina MiSeq system.

Results:

We identified 12,960 to17,601 mutations in each sample, with a total of 16,466 somatic mutations in total. Some 15,533 variants were single nucleotide polymorphisms (SNPs), 129 were substitutions, 415 were insertions and 389 were deletions. When taking into account the coding region and protein impact, 1,875 variants were synonymous and 1,956 were non-synonymous SNPs. Among non-synonymous SNPs, 1,862 were missense, 13 nonsense, 35 frameshifts, 11 nonstop, 3 misstart, 15 splices disrupt and 17 in-frame indels. A total of 86 variants were located in leukaemia-related genes of which 32 variants were located in the coding regions of GLI2, SP140, GATA2, SMAD5, KMT2C, CDH17, CDX2, FLT3, PML and MOV10L1.

Conclusions:

Detection and identification of secondary genetic alterations are important in identifying new therapeutic targets and developing rationally designed treatment regimens with less toxicity in ALL patients.

Molecular studies reveal a MLL-MLLT3 gene fusion displaced in a case of childhood acute lymphoblastic leukemia with complex karyotype

Rearrangement of the mixed lineage-leukemia gene (MLL-r) is common in hematological diseases and is generally associated with poor prognosis. The mixed-lineage leukemia gene translocated to, 3 (MLLT3) gene (9p22) is a frequent MLL-r partner (∼18% of leukemias with MLL rearrangement) and is characterized by the translocation t(9;11) (p22;q23), forming an MLL-MLLT3 gene fusion. MLL-r are usually simple reciprocal translocations between two different chromosomes, although karyotypes with complex MLL-r have been observed. We present a rare case of a child with acute lymphoblastic leukemia with a complex karyotype in which the classical t(9;11) (p22;q23) was cryptically relocated into a third chromosome in a balanced three-way translocation. At the genome level, however, the MLL-MLLT3 three-way translocation still displayed both reciprocal fusion transcripts. This argues in favor for a model where a simple two-way t(9;11) (p22;q23) was likely the first step that then evolved in to a more complex karyotype. Multicolor banding techniques can be used to greatly refine complex karyotypes and its chromosomal breakpoints. Also in the presence of putative new rearrangements, Long distance inverse-PCR is an important tool to identify which gene fusion is involved.