Transcriptional analysis of biopsy tissue indicated that type II interferon, IFNG, not type I (IFNA4 and IFNB1) nor type III (IFNL1, IFNL2, IFNL3) interferons, was the prevalent interferon gene detected in ulcer lesions and 8 weeks post-healed skin (Figure 3A). Here, IFNA4 is linked to ulcer disease.