The levels of serum homocysteine (Figure 1A), urinary and serum methylmalonic acid (Figures 1B,C) in cblC-MMA patients were obviously higher than control group and HHcy group, which showed no significance between cblC-MMA patients with cognitive impairment and with normal cognition, no significance among cblC-MMA subgroups of mild, moderate and severe cognitive impairment. This evidence concerns the gene CBLC and Cognitive impairment.