Further supporting this observation, microarray expression profiling of 246 media and adventitia samples from aortic tissues revealed that IRF8 was significantly upregulated among transcription factors in the AAA group (Figure 1C).[16] ImmGen analysis of these differentially expressed transcription factors confirmed that IRF8 is highly enriched in the dendritic cell lineage (Figure S1B, Supporting Information),[17] suggesting that IRF8 may mediate the pro‐expansion effects of dendritic cells in AAA. Here, IRF8 is linked to triple-A syndrome.