KMT2A (MLL) rearrangements observed in pediatric/young adult T-lymphoblastic leukemia/lymphoma: A 10-year review from a single cytogenetic laboratory

Genes Chromosomes Cancer. 2018 Nov;57(11):541-546. doi: 10.1002/gcc.22666. Epub 2018 Sep 10.

Abstract

T-lymphoblastic leukemia/lymphoma (T-ALL/LBL) accounts for approximately 15% of pediatric and 25% of adult ALL. While the underlying frequency of KMT2A (MLL) gene rearrangements has been identified in approximately 4-8% of T-ALL/LBL cases, a paucity of literature is available to characterize further the KMT2A rearrangements in pediatric/young adult T-ALL/LBL. A 10-year retrospective review was performed to identify KMT2A rearrangements in specimens sent for T-ALL/LBL fluorescence in situ hybridization studies in patients under the age of 30 years. Of 806 T-ALL/LBL FISH studies performed on unique individuals, 27 (3.3%) harbored KMT2A rearrangements. Nineteen patients were male and eight were female (M:F ratio, 2.4:1) with ages ranging from 1 to 20 years (mean 12, median 12). Of the 27 cases, nine (33%) had KMT2A/MLLT1 fusions, eight (30%) had KMT2A/AFDN fusions, two (7%) had KMT2A/ELL fusions, and one (4%) had a KMT2A/MLLT10 fusion. In addition, five (19%) had KMT2A rearrangements with unidentified gene fusion partners and two (7%) had 3'KMT2A deletions. Our results indicate that MLLT1 and AFDN account for the majority (63%) of KMT2A gene partners in pediatric/young adult T-ALL/LBL, while no KMT2A/AFF1 or KMT2A/MLLT3 fusions were observed despite their common identification in B-ALL and acute myeloid leukemia, respectively. In addition to diagnostic and prognostic value, detecting specific KMT2A fusions may also be of clinical importance in the era of targeted therapies.

Keywords: Chromosome analysis; Fluorescence in situ hybridization (FISH); KMT2A MLL; T-lymphoblastic leukemia/lymphoma (T-ALL/LBL).

MeSH terms

  • Adolescent
  • Adult
  • Child
  • Child, Preschool
  • Cytogenetic Analysis
  • Female
  • Gene Rearrangement / genetics*
  • Histone-Lysine N-Methyltransferase / genetics*
  • Humans
  • In Situ Hybridization, Fluorescence
  • Infant
  • Male
  • Myeloid-Lymphoid Leukemia Protein / genetics*
  • Precursor T-Cell Lymphoblastic Leukemia-Lymphoma / genetics*
  • Retrospective Studies
  • Young Adult

Substances

  • KMT2A protein, human
  • Myeloid-Lymphoid Leukemia Protein
  • Histone-Lysine N-Methyltransferase