MDM2 and hepatocellular carcinoma: With respect to MDM2 SNP309 polymorphism, a meta-analysis by Ma et al. [13] found that the MDM2 SNP309 polymorphism was associated with an increased HCC risk in Asians and Caucasians, however, they failed to include all eligible studies in the meta-analysis [14], [15], [16], which make their conclusions questionable.