Sensitive detection of GATA1 mutations using complementary DNA‐based analysis for transient abnormal myelopoiesis associated with the Down syndrome

Introduction GATA1 mutation plays an important role in initiating transient abnormal myelopoiesis (TAM) and in the clonal evolution towards acute megakaryoblastic leukaemia (AMKL) associated with Down syndrome (DS). This study aimed to develop and validate the clinical utility of a complementary DNA (cDNA) analysis in parallel with the conventional genomic DNA (gDNA) Sanger sequencing (Ss), as an initial screening test for GATA1 mutations. Methods GATA1 mutations were evaluated using both gDNA and cDNA in 14 DS patients using Ss and fragment analysis (FA), respectively. Results The detection sensitivity of conventional gDNA sequencing was limited in low blast percentage TAM (LBP‐TAM); however, cDNA‐based Ss readily detected all the pathognomonic GATA1 mutations. The cDNA‐based FA readily detected GATA1 frameshift mutation with a reliable sensitivity ranging from 0.005% to 0.01% of clonal cells. Conclusions GATA1 mutations are heterogeneous; therefore, we would like to propose a dual cDNA and gDNA analysis as a standard diagnostic approach, especially for LBP‐TAM. cDNA‐based FA promises an excellent sensitivity for detecting frameshift GATA1 mutations in the longitudinal clonal evolution towards AMKL without using a patient specific primer.