Detection of clonal selection by multicolor flow cytometry in TAM with multiple GATA1 mutations

Area of Science:

• Hematology
• Oncology
• Genetics

Background:

• Transient abnormal myelopoiesis (TAM) affects ~10% of neonates with Down syndrome (DS).
• About 20% of TAM cases progress to myeloid leukemia associated with DS (ML-DS).
• TAM typically originates from a single clone with a GATA1 mutation, but heterogeneous clones occur in ~8% of cases.

Purpose of the Study:

• To report a unique case of TAM with multiple distinct GATA1 mutations.
• To investigate the evolution of a minor clone to overt ML-DS.
• To evaluate flow cytometry (FCM) as a tool for early detection of leukemogenic clones in TAM.

Main Methods:

• Case study of a neonate with Down syndrome and TAM.
• Genetic analysis to identify GATA1 mutations.
• Flow cytometry (FCM) to monitor blast surface marker expression.
• Treatment with low-dose cytarabine.

Main Results:

• A minor clone with a distinct GATA1 mutation evolved into overt ML-DS by 59 days of age.
• Changes in blast surface marker expression detected by FCM correlated with the emergence of the leukemogenic clone.
• This occurred after a single course of low-dose cytarabine.

Conclusions:

• Flow cytometry (FCM) may be a valuable tool for early detection of leukemogenic clonal expansion in TAM patients with multiple GATA1 mutations.
• This case highlights the potential for minor clones to drive leukemogenesis in TAM.
• Early detection of evolving clones is crucial for managing TAM and preventing progression to ML-DS.