Abstract
Background: While there is enough convincing evidence in childhood acute lymphoblastic leukemia (ALL), the data on the pre-natal origin in childhood acute myeloid leukemia (AML) are less comprehensive. Our study aimed to screen Guthrie cards (neonatal blood spots) of non-infant childhood AML and ALL patients for the presence of their respective leukemic markers.
Methods: We analysed Guthrie cards of 12 ALL patients aged 2-6 years using immunoglobulin (Ig) and T-cell receptor (TCR) gene rearrangements (n = 15) and/or intronic breakpoints of TEL/AMLI fusion gene (n = 3). In AML patients (n = 13, age 1-14 years) PML/RARalpha (n = 4), CBFbeta/MYHII (n = 3), AMLI/ETO (n = 2), MLL/AF6 (n = 1), MLL/AF9 (n = 1) and MLL/AF10 (n = 1) fusion genes and/or internal tandem duplication of FLT3 gene (FLT3/ITD) (n = 2) were used as clonotypic markers.
Assay sensitivity determined using serial dilutions of patient DNA into the DNA of a healthy donor allowed us to detect the pre-leukemic clone in Guthrie card providing 1-3 positive cells were present in the neonatal blood spot. Results: In 3 patients with ALL (25%) we reproducibly detected their leukemic markers (Ig/TCR n = 2; TEL/AMLI n = 1) in the Guthrie card.
We did not find patient-specific molecular markers in any patient with AML. Conclusion: In the largest cohort examined so far we used identical app roach for the backtracking of non-infant childhood ALL and AML.
Our data suggest that either the prenatal origin of AML is less frequent or the load of pre-leukemic cells is significantly lower at birth in AML compared to ALL cases.