Case report: Pediatric acute lymphoblastic leukemia with trisomy 5 as sole cytogenetic abnormality

Acute lymphoblastic leukemia (ALL) is the most common malignancy in childhood and represents about 75 -80% of ALL in pediatric age group. ALL is characterised by uncontrolled proliferation of abnormal, immature lymphocytes and their progenitors and replacing the bone marrow elements and other lymphoid organs by leukemic cells (ALL blasts). The 5 year survival rate for childhood ALL is about 90% overall, children in lower risk groups have a better prognosis than those in higher risk group. Risk assessment is mainly based on cytogenetic and molecular factors in addition, clinical symptoms and signs, White blood cell count at diagnosis are all recognized for stratification. In present case the cytogenetic analysis showed the presence of trisomy 5 as a sole numerical abnormality. Trisomy 5 accounts for aneuploidy change in the cytogenetic analysis. The gain or loss of whole chromosome, ie aneuploidy is a major genomic insult in human cancers. Aneuploidy is observed in ~90% of solid tumors and~60% of hematological maignancies. The increased gene expression in trisomy 5 causes chromosomal instability (CIN), microsatellite instability (MIN) and genomic instabilty which inturn causes the cancer genome to undergo evolution, adaptation and favors tumor progression in patients with B cell acute lymphoblastic leukemia.