Serum hyaluronic acid as an early indicator of disease severity in transient abnormal myelopoiesis associated with Down syndrome

Transient abnormal myeloproliferative syndrome (TAM) is a neonatal preleumatic syndrome that affects approximately 5–10% of newborns with Down syndrome. Most affected infants recover spontaneously, whereas approximately 20% develop severe disease with progressive cytopenia and multiple organ dysfunction [ 1 ]. These severe manifestations are associated with extreme leukocytosis, abnormal or immature immune responses, and severe liver dysfunction characterized by hypoalbuminemia, hyperbilirubinemia, or coagulopathy [ 2 ]. Because leukemogenesis originates from hematopoietic precursor cells within the fetal liver, abnormal hematopoiesis disrupts the hepatic microenvironment, causing hepatic dysfunction that contributes to disease severity. Hence, we assessed liver-related biomarkers measurable at diagnosis to determine patients at high risk of critical outcomes associated with TAM.