RAB27A and agammaglobulinemia: Regarding genetic variants, patients who had UNC13D deficiency with hypogammaglobulinemia were more likely to carry missense variants (75% vs. 20.47%), have a higher frequency of mutated sites within gene exons (87.5% vs. 53.39%), and show a greater likelihood of variants affecting the domain responsible for interaction with RAB27α (Figure 2, Table 6).