An unusual case of high hyperdiploid childhood ALL with cryptic BCR/ABL1 rearrangement

Genomic Analyses of Pediatric Acute Lymphoblastic Leukemia Ph+ and Ph-Like-Recent Progress in Treatment

Pediatric acute lymphoblastic leukemia (ALL) with t(9;22)(q34;q11.2) is a very rare malignancy in children. Approximately 3-5% of pediatric ALL patients present with the Philadelphia chromosome. Previously, children with Ph+ had a poor prognosis, and were considered for allogeneic stem cell transplantation (allo-HSCT) in their first remission (CR1). Over the last few years, the treatment of childhood ALL has significantly improved due to standardized research protocols. Hematopoietic stem cell transplantation (HSCT) has been the gold standard therapy in ALL Ph+ patients, but recently first-generation tyrosine kinase inhibitor (TKI)-imatinib became a major milestone in increasing overall survival. Genomic analyses give the opportunity for the investigation of new fusions or mutations, which can be used to establish effective targeted therapies. Alterations of the IKZF1 gene are present in a large proportion of pediatric and adult ALL Ph+ cases. IKZF1 deletions are present in ~15% of patients without BCR-ABL1 rearrangements. In BCR-ABL1-negative cases, IKZF1 deletions have been shown to have an independent prognostic impact, carrying a three-fold increased risk of treatment failure. The prognostic significance of IKZF1 gene aberrations in pediatric ALL Ph+ is still under investigation. More research should focus on targeted therapies and immunotherapy, which is not associated with serious toxicity in the same way as classic chemotherapy, and on the improvement of patient outcomes. In this review, we provide a molecular analysis of childhood ALL with t(9;22)(q34;q11.2), including the Ph-like subtype, and of treatment strategies.

Duplication 1q is highly correlated with poor prognosis in high hyperdiploid pediatric B-acute lymphoblastic leukemia

BACKGROUND

The role of structural abnormalities in high hyperdiploidy (HeH) has been debatable, with few studies that addressed recurrent translocations with concurrent HeH (t-HeH). We aimed at the characterization of HeH cases in pediatric B-acute lymphoblastic leukemia (B-ALL) patients with special emphasis on the structural abnormalities including t-HeH.

PATIENTS AND METHODS

Our study included all patients diagnosed with HeH over the period from January 2016 to April 2019 presenting to the Pediatric Oncology Department, National Cancer Institute, Cairo University.

RESULTS

Among 480 de novo B-ALL pediatric patients, HeH was detected in eighty (16.7%) cases with a median age of 5 years. t-HeH was identified in 17/480 (3.5%) cases: 9(1.9%) with t(12;21), 7(1.5%) with t(9;22), and 1(0.2%) with t(4;11). Duplication (1q) was the most prevalent structural abnormality in c-HeH (hyperdiploidy without recurrent translocations) (n = 12,15%). Children ≥10 years or presenting with white blood cells (WBC) ≥50 × 10⁹ /L) had an inferior 3 year-overall survival as compared to younger children (P = .003), and to lower WBC (P = .02). Duplication (1q) was an independent adverse parameter on the disease-free survival (DFS) of c-HeH patients (P = .004).

CONCLUSIONS

Older age and WBC ≥ 50 × 10⁹ /L were adverse prognostic factors. Duplication (1q) is correlated with lower DFS in c-HeH patients. t-HeH has distinct patterns of chromosomal gain.

A Novel Variant Rearrangement of the Rare Aberration dic(17;20)(p11.2;q11.2) Characterized by Array-CGH as an Insertion in a Patient with Myelodysplastic Syndrome of Multilineage Dysplasia (MDS-MLD)

We report on a novel variant of the dicentric chromosome 17;20 (dic (17;20)(p11.2;q11.2) in a patient with de novo myelodysplastic syndrome (MDS). Based on FISH and array-CGH, the variant turns out to be an insertion of chromosome 17 (17p11.2-telomere 17) into chromosome 20 with breakpoints at 20q11.22 and 20q13.33. Based on conventional chromosome analysis and G-banding patterns, the region 17p11.2-17q25 was directly inserted between 20q11.22 and 20q13.33. The breakpoint junctions occurred within KCNJ12 (17p11.2), UQCC1 (20q11.2), and CDH4 (20q13.3), leading to 5' deletions of all the genes and positioning the 3' of UQCC1 next to KCNJ12 at 17p11.2 and CDH4 next to an unknown gene at 17q25-20q13.3. In addition, the centromere of chromosome 17 was not active, transforming the primary constriction to a flat band. Therefore, the novel insertion variant is a pseudo dicentric derivative chromosome with one functional centromere: 45,XX,der(17;20)del(20)(q11.22q13.33)ins(20;17)(q11.2;p11.2q25). A review of the literature of all dic(17;20) cases is presented. For the first time, we report an array-CGH characterization of such rare variant that revealed to be an insertion.