A Novel NRAS Variant Near the Splice Junction in Moroccan Childhood Acute Lymphoblastic Leukemia: A Molecular...

The RAS genes are importantly implicated in oncogenesis and are frequently mutated in childhood acute lymphoblastic leukemia. This study is the first to our knowledge, to determine the mutational status of NRAS and KRAS genes in Moroccan pediatric acute lymphoblastic leukemia (ALL). Polymerase chain reaction and Sanger sequencing were performed for 45 ALL samples to explore the coding exons. The functional effect of the mutation was evaluated using in silico prediction tools and molecular modeling. We identified a novel variant c.290 G > C p.Arg97Thr within NRAS gene in a patient with T-ALL, which is a rare missense point mutation affecting the last base of exon 3. Analyses revealed that p.Arg97Thr impairs the adjacent splice site efficiency. Moreover, it leads to structural modifications at local and global levels of the protein through the loss of hydrogen bonds. Additionally, the molecular dynamics (MD) simulation showed that it slightly increases the stability of NRAS protein by locally decreasing the flexibility of the mutated region. No variant was detected within KRAS gene. R97 at NRAS gene is an overlapping splice site residue. Our findings suggest that the NRAS p.Arg97Thr variant may disrupt the splicing machinery and functions of the protein, thus playing a vital role in leukemogenesis. In addition, the highly druggable pocket may possibly be studied for its therapeutic implications.