Spatial transcriptomics and single-cell RNA sequencing analyses have revealed that TNC is highly concentrated in leukocyte-infiltrated areas of AD lesional skin, where it colocalizes with COL18A1+ fibroblasts, a distinct subpopulation characterized by expression of the COL18A1 gene encoding collagen type XVIII alpha 1 chain protein (Mitamura et al., 2023). The gene discussed is COL18A1; the disease is Alzheimer disease.