A subsequent study reported that a patient with RIDDLE syndrome (radiosensitivity, immunodeficiency, dysmorphic features and learning difficulties) was defective in the recruitment of 53BP1 and BRCA1 to the DSBs [30], indicating the presence of another protein in the RNF8-dependent 53BP1 recruitment process. This evidence concerns the gene TP53BP1 and immunodeficiency disease.