Frequency of copy number abnormalities in common genes associated with B-cell precursor acute lymphoblastic leukemia cytogenetic subtypes in Brazilian children

Abstract

Copy number alterations (CNAs) in genes committed to B-cell precursors have been associated with poor survival in subgroups of patients with B-cell precursor acute lymphoblastic leukemia (BCP-ALL). We investigated submicroscopic alterations in a series of 274 Brazilian children with BCP-ALL by multiplex ligation-dependent probe amplification and evaluated their correlation with clinical and laboratory features. The relevance of overlapping CNA abnormalities was also explored. Deletions/amplifications in at least one gene were identified in 83% of the total series. In children older than 2 years, there was a predominance of CNAs involving deletions in IKZF1, CDKN2A, and CDKN2B, whereas the pseudoautosomal region 1 (PAR1) had deletions that were found more frequently in infants (P <0.05). Based on the cytogenetic subgroups, favorable cytogenetic subgroups showed more deletions than other subgroups that occurred simultaneously, specifically ETV6 deletions (P <0.05). TCF3-PBX1 was frequently deleted in RB1, and an absence of deletions was observed in IKZF1 and genes localized to the PAR1 region. The results corroborate with previous genome-wide studies and aggregate new markers for risk stratification of BCP-ALL in Brazil.

Keywords: Acute lymphoblastic leukemia; IKZF1; MLPA; copy number alterations; multiplex ligation-dependent probe amplification.