Aberrant myelomonocytic CD56 expression in Down syndrome is frequent and not associated with leukemogenesis

Area of Science:

• Hematology
• Genetics
• Pediatric Oncology

Background:

• Children with Down syndrome (DS) have a higher risk of transient abnormal myelopoiesis (TAM) and acute leukemia.
• Aberrant CD56 expression on myeloid leukemic blasts is noted in DS patients.
• CD56 expression in acute myeloid leukemia (AML) is generally linked to leukemogenesis.

Purpose of the Study:

• To investigate CD56 expression patterns in mature myelomonocytic cells.
• To compare these patterns in DS patients with TAM, non-TAM conditions, and leukemia.
• To understand the role of CD56 in DS-associated leukemogenesis.

Main Methods:

• Retrospective flow cytometric analysis.
• Examination of granulocyte and monocyte populations.
• Comparison across DS patient groups (TAM, non-TAM, leukemia).

Main Results:

• Aberrant/dysplastic CD56 expression on granulocytes and monocytes is a characteristic of most DS patients.
• This expression is present irrespective of TAM or leukemia status.
• Increased CD56 in DS may be due to RUNX1 gene effects from trisomy 21 and cell maturational state.

Conclusions:

• CD56 aberrant expression on myeloid cells is common in Down syndrome patients.
• Unlike in non-DS AML, CD56 overexpression does not appear to drive leukemogenesis in DS AML.
• RUNX1 gene dosage and cell maturation are potential factors contributing to CD56 expression in DS.