This Down Syndrome Critical Region (DSCR) is mapped to the long arm of chromosome 21 and covers 5.4 Mb containing genes regulating cellular processes, such as splicing (RBM1 (RNA-Binding Motif 1), U2AF1 (U2 Small Nuclear RNA Auxiliary Factor 1), U2AF1L5 (U2 Small Nuclear RNA Auxiliary Factor 1 Like 5)), DNA methylation (PRMT2 (Protein Arginine Methyltransferase 2), N6AMT1 (N(6)-Adenine Specific DNA Methyltransferase)), and metabolism (SOD1 (Superoxide Dismutase 1)). This evidence concerns the gene U2AF1 and Down syndrome.