INCLUDE: The Epidemiology of Transient Leukemia in Newborns with Down Syndrome
The INCLUDE (INvestigation of Co-occurring conditions across the Lifespan to Understand Down syndromE) Project is an NIH-wide collaboration that seeks to improve health and quality-of-life for people with Down syndrome. The INCLUDE Project Data Coordinating Center and partners created the INCLUDE Data Hub, a centralized data resource that allows access to large-scale clinical and multi-omics datasets specific to Down syndrome and supports collaborative, cloud-based analysis to accelerate scientific discoveries related to Down syndrome and its co-occurring conditions.
Down syndrome (DS) is associated with a remarkably high risk of childhood acute myeloid leukemia (AML), with an approximately 500-fold increased risk of the rare subtype acute megakaryoblastic leukemia. Though largely treatable, a proportion of myeloid leukemia in DS (ML-DS) patients relapse with dismal survival. ML-DS is preceded by a preleukemia, transient abnormal myelopoiesis (TAM), which presents clinically at birth and is driven by somatic truncating mutations in the erythro-megakaryocytic transcription factor gene GATA1. Up to 15% of DS newborns have TAM, and this can be fatal in up to 20% of cases. A further 10-15% of newborns with DS harbor subclonal GATA1 mutations with clinically silent disease (i.e., Silent TAM). Of the DS newborns with either TAM or Silent TAM (i.e., transient leukemia), up to 15% will acquire additional somatic mutations and progress to ML-DS. We predict that germline variation modifies the risk of developing somatic truncating GATA1 mutations, the first step towards ML-DS, however this has yet to be examined. To address this, the main aim of this X01 study is to perform the first genetic association study of GATA1 mutations in DS, through whole-genome sequencing (WGS) of 470 DS newborns in the Oxford Down Syndrome Cohort Study (ODSCS). Targeted sequencing of GATA1 has already been performed in the 470 DS newborns in the ODSCS, with 130 (28%) confirmed to harbor a somatic truncating GATA1 mutation. We will perform a genome-wide association study (GWAS) of GATA1 mutations to assess genetic variation genome-wide, in particular focusing on variants in candidate genes on the trisomic chromosome 21, RUNX1, ERG, ETS2, and DYRK1A, which have previously been associated with upregulation of GATA1. We will also carry out a chromosome X-wide association study (XWAS) to investigate genetic variation at the GATA1 gene, which resides on chromosome X. WGS data will also enable us to assess the potential role of copy number variation in the risk of transient leukemia in DS. Discovering genetic risk factors for GATA1 mutations in DS may reveal targets for new targeted therapies for TAM, and also inform the etiology of ML-DS as well as AML in the non-DS population. Finally, the ODSCS includes rich phenotypic data for the 470 DS newborns, including clinical diagnosis of TAM and other hematologic complications, complete blood counts, maternal pregnancy complications, and information on congenital heart disease and other birth defects. Thus, whole genome sequencing data in DS newborns from the ODSCS will provide a rich resource for the DS research community.