Objective　To investigate the clinical characteristics and genetic mechanism of Imerslund-Gr?sbeck syndrome (IGS). Methods　The clinical data and genetic test of a patient with IGS were collected and analyzed retrospectively. Related literatures were reviewed. Results　The patient presented with malnutrition, exercise retardation, megaloblastic anemia, vitamin B12 deficiency, and mild-moderate benign proteinuria. Whole exome sequencing identified a homozygous c.742C>T(p.Q248*) mutation of the AMN gene in the patient. Sanger sequencing found both of his parents are heterozygous carriers. Conclusion For children with megaloblastic anemia complicated with mild to moderate benign proteinuria, the possibility of IGS should be considered.