Hematologic Manifestations of Trisomy 21

The most common human chromosome aneuploidy, trisomy 21 (Down syndrome [DS] and Down syndrome mosaic), is associated with a wide spectrum of hematologie abnormalities in the three hematopoietic lines. Included in these abnormalities are peculiar hematologie findings in the neonate, transient leukemia (TL), high mean corpuscular volume throughout life, high incidence of acute megakaryoblastic leukemia (AMKL) in infancy, increased incidence of leukemia throughout life, and abnormalities of the immunologie system. Most of the newborns with any of the above-mentioned hematologie abnormalities may not have any other clinical sign or symptom. However, some infants with TL may present with massive hepatosplenomegaly, cutaneous infiltrates, hydrops fetalis (Zipursky et al. 1999) or liver fibrosis (Yagihashi et al. 1995; AlKasim et al. 2002). Although, TL is thought to be a benign self-limited disorder, it can be fatal at initial presentation. Moreover, leukemia may develop in one-third of the patients who initially recover from TL (Homans et al. 1993).