Dicentric chromosome in the bone marrow of a child with megakaryoblastic leukaemia and Down's syndrome.

Abstract
A two year old girl with Down''s syndrome (constitutional karyotype: 47 +21), presenting with pancytopenia, developed acute megakaryoblastic leukaemia (AMKL). Her bone marrow contained an abnormal clone with a novel dicentric chromosome derived from chromosomes 5 and 7 (karyotype 46, XX, -5, -7, + dic (5; 7) (p 13; p 11.2), +21). This case provides further evidence for a connection between chromosome 21 and this unusual from of childhood leukaemia, and raises questions about the loss of short arm material from chromosomes 5 and 7 compared with the more usual monosomy or long arm loss.
Keywords