PTGDR2 and Alzheimer disease: showed by single-cell RNA sequencing that ILCs in the epidermis and dermis of AD patients and normal healthy subjects could be classified into four subgroups, namely, ILC1/3, ILC2, ILC1/NK, and NK, with ILC2s (IL7R, PTGDR2, and GATA3) having the most distinct signature (42).