BackgroundLymphocyte enhancer factor-1 (LEF-1) is a member of the LEF-1/TCF family of transcription factors that are critically involved in canonical Wnt/β-catenin Signaling to regulate B Lymphocyte proliferation and survival. Alteration of LEF1 expression and function leads to leukemogenesis as well as other several neoplasms.Aimsto identify mutations in exons two and three of the LEF1 among B-CLL Sudanese patients. Also, to functionally analyze the detected SNPs using different in silico tools.Materials and methodsImmuno-phenotype for the detection of B cells CD5 and CD19 markers was performed on 128 B-CLL Sudanese patients by using a flow cytometry technique. DNA extraction, conventional PCR, and Sanger sequencing were applied to the LEF1 gene. Also, we performed a mutational analysis for identified SNPs using bioinformatics tools.ResultsA positive CD5 & CD19 expression was found in B-CLL patients. No mutation was observed in exon two. While four mutations were observed in exon three; two of them were not reported in previous studies. Interestingly, splicing analysis predicted that these mutations could lead to splicing defects in LEF1 pre-mRNA due to their potential effects on splicing regulatory elements (i.e. ESE).Conclusionthe two mutations Pro134Pro and Ile135Asn (novel mutation) were detected in all enrolled CLL patients and they could be used as diagnostic and/or prognostic markers for CLL. Therefore, further in vitro and in vivo functional studies with a large sample size are required to verify the splicing effect of the detected mutations in LEF1 pre-mRNA.