Collagen synthesis requires amino acid blocks derived from metabolic pathways.[32] When we analyzed scRNA‐seq data from patients with PF (GSE136831) using scFEA and divided the fibroblasts into CTSK‐positive and CTSK‐negative groups, we found that glutamate was significantly enriched in CTSK‐positive fibroblasts (Figure5A). The gene discussed is CTSK; the disease is pemphigus foliaceus.