Molecular Cytogenetic Characterization of a Complex Karyotype of a Pediatric Male Patient with B-Acute Lymphoblastic Leukemia.

Objectives: B-Acute lymphoblastic leukemia (B-ALL) is a malignant disease that arises from several cooperative genetic mutations in a single B-lymphoid progenitor, leading to altered blast cell proliferation, survival and maturation, and eventually the lethal accumulation of leukemic cells. B-ALL accounts for about 12% of all childhood and adult leukemias diagnosed in developed countries, and 60% of those diagnosed are patients younger than 20 years old. As the most common cancer in children (25% of all cases) with a peak incidence in patients between the ages of two and five years, with a second, smaller peak in the elderly, the factors predisposing children and adults to ALL remain largely unknown. Herein we present an eight-year-old male patient diagnosed with B-ALL. Chromosome studies of 20 G-banded metaphases of the bone marrow detected an abnormal male karyotype with loss of 9p [i(9)(q10)] and loss of 17p [der(17)(?::17q11.2->17p11.2::17p11.2->17qter)] within the context of a complex karyotype in eight metaphase cells. Four of these abnormal metaphases showed additional material of unknown origin on chromosome 12 at p11.2 [add(12)(p11.2)]. Metaphase FISH analysis was crucial to characterize such complex chromosomal abnormalities, underscoring the importance of molecular cytogenetics in characterizing complex karyotypes in this hematological malignancy.