Junction characteristics of unproductive Ig and TR rearrangements. (A) Median number of N-nucleotides, (B) deletions, and (C) P-nucleotides in unproductive unique IgH, IgK, IgL, TRD, and TRB rearrangements in healthy controls and XRCC4/LIG4- and XLF-deficient patients. The numbers of productive unique rearrangements used to calculate the median are listed in supplemental Table1. *P ≤ .05; **P ≤ .01; ***P ≤ .001 by 2-tailed Mann-Whitney U test.