Hematological disorders in children with Down syndrome

Hematological abnormalities are common in children with down syndrome (DS), mainly during childhood.

DS newborns can develop hematological benign conditions that resolve spontaneously within 1 -2 months. However, about 10% of them can present transient abnormal myelopoiesis (TAM), characterized by the presence of circulating blasts. About 80% of DS neonates with TAM undergo spontaneous resolution of both clinical and laboratory abnormalities within 3-6 months after birth. However, some newborns with TAM may develop acute myeloid leukemia associated with DS (ML-DS), usually after an interval without signs of leukemia. GATA1 mutations are stable molecular markers that may monitor the presence of minimal residual disease (MRD) after TAM resolution. Moreover, DS children have a 10-20-fold increased risk of developing acute lymphoblastic leukemia (ALL) and acute myeloid leukemia (AML). The predisposition to develop leukemia occurs both in children with complete trisomy 21 and in those with mosaic trisomy, suggesting an important role of chromosome 21 in leukemogenesis.

In contrast to the excellent prognosis of ML-DS obtained likewise with low doses of chemotherapy, DS-ALL patients show worse outcomes than non-DS children, therefore advances and risk-stratified treatment adjustments are mandatory for this particular set of patients.