ERCC2 and B cell deficiency: Additionally, we conducted immunophenotyping of the parents of patient 1 and found that neither the father (ERCC2 c.335G>A/WT) nor the mother (ERCC2: c.1378-7_1387dup/WT) exhibited B cell deficiency (data not shown) or increased UV sensitivity in their LCLs (Supplementary Figure 2).