In this study, the genotyping of the MDM2-SNP309T>G (rs2279744) polymorphism, assessed in 70 RB families (212 carriers of germline mutations and 114 relatives), revealed a significant association of the SNP309G allele with the presence of bilateral or unilateral tumors among mutation carriers reflecting a recessive contribution of MDM2 to tumor susceptibility [21]. Here, MDM2 is linked to retinoblastoma.