B-cell acute lymphoblastic leukemia (B-ALL) is the most common childhood hematological malignancy worldwide. Treatment outcomes have improved dramatically in recent years; despite this, relapse is still a problem, and the potential molecular explanation for this remains an important field of study. We performed microarray and single-cell RNA-Seq data mining, and we selected significant data with a P -value<0.05. We validated BRCA1 gene expression by means of quantitative (reverse transcription-polymerase chain reaction.) We performed statistical analysis and considered a P -value<0.05 significant. We identified the overexpression of breast cancer 1, early onset (BRCA1; P -value=2.52 -134 ), by means of microarray analysis. Moreover, the normal distribution of BRCA1 expression in healthy bone marrow. In addition, we confirmed the increases in BRCA1 expression using real-time (reverse transcription-polymerase chain reaction and determined that it was significantly reduced in patients with relapse ( P -values=0.026). Finally, we identified that the expression of the BRCA1 gene could predict early relapse ( P -values=0.01). We determined that low expression of BRCA1 was associated with B-cell acute lymphoblastic leukemia relapse and could be a potential molecular prognostic marker.