Two pairs of monozygotic twins with concordant acute lymphoblastic leukemia (ALL): case report.

The occurrence of leukemia in twins is rare but has a crucial implication in the genetic research of leukemia. This report presents 2 pairs of monozygotic twins with precursor B-cell acute lymphoblastic leukemia. Mixed lineage leukemia (MLL)-AF4 fusion genes were found in the twin sisters. This study is the first to report on infant ALL harboring the 46,XY, -4, +10, -13, del(14)(q24), -15, +2mar[4 cells] complex chromosome abnormality. Our report showed that the unified cytogenetic features in monozygotic twins and MLL-AF4 fusion gene may be necessary but insufficient for the clinical development and prognosis of identical twins with leukemia.