Leukemogenesis in infants and young children with trisomy 21

Area of Science:

• Pediatric Oncology
• Hematology
• Genetics

Background:

• Children with Down syndrome (DS) exhibit a markedly increased susceptibility to leukemia, specifically acute myeloid leukemia (ML-DS) and acute lymphoblastic leukemia (ALL-DS).
• ML-DS originates prenatally, often presenting as transient abnormal myelopoiesis (TAM), a condition linked to trisomy 21 and GATA1 mutations.
• DS-ALL, predominantly B-lineage, is associated with CRLF2 gene rearrangements and mutations in JAK2 or RAS genes.

Purpose of the Study:

• To elucidate the complex mechanisms of leukemogenesis in Down syndrome.
• To understand the distinct genetic drivers and clinical presentations of ML-DS and DS-ALL.
• To identify potential therapeutic targets for improving outcomes in pediatric leukemia associated with DS.

Main Methods:

• Analysis of primary cells and established model systems.
• Investigation of genetic mutations, including GATA1, cohesin genes, CRLF2, JAK2, and RAS.
• Correlation of genetic findings with clinical presentation and outcomes in DS patients.

Main Results:

• ML-DS arises from cooperation between fetal hematopoiesis abnormalities and GATA1 mutations, with a subset progressing due to secondary mutations.
• DS-ALL cases frequently show CRLF2 rearrangements, often with JAK2 or RAS mutations.
• While ML-DS treatment yields high survival rates (~90%), DS-ALL outcomes are poorer compared to non-DS ALL.

Conclusions:

• Trisomy 21 plays a complex, context-dependent role in DS leukemogenesis.
• Understanding the specific genetic underpinnings of ML-DS and DS-ALL is crucial for targeted therapy.
• Further research into primary cells and model systems shows promise for improving management, especially for relapsed cases where outcomes remain poor.