Fluorescence in Situ Hybridisation (FISH) is the First Tool to Identify Hypodiploidy in Paediatric Acute Lymphoblastic Leukaemia

Abstract

Hypodiploidy has a low incidence in childhood acute lymphoblastic leukaemia (ALL). Patients are usually stratified into three subgroups, to allocate the correct treatment according to their ploidy level: high hypodiploidy (40-45 chromosomes), low hypodiploidy (33-39 chromosomes) and near haploidy (23-29 chromosomes). In this paper, a case is presented of near-haploid childhood ALL where fluorescence in situ hybridisation (FISH) provided an insight into the near-haploidy chromosomal aberration initially missed on routine karyotyping due to culture effect and analysis software constraints. FISH primary results followed by further confirmatory studies, inclusive of karyotyping and single nucleotide polymorphism (SNP) microarray, clinically placed the patient in the correct treatment stratification. The patient remained in morphological and cytogenetic remission 12 months after commencing the high risk arm of an international collaborative (*AIEOP-BFM-ALL [Associazione Italiana Ematologia Oncologia Pediatrica-Berlin-Franklin-Munste]) 2009 treatment protocol for children and adolescents with ALL.