In this study, to clarify whether the skin abnormalities in Vdr-KO rats that follow alopecia are related to the dermal cyst formation or arise through completely different mechanisms, we attempted to elucidate the function of VDR in maintaining skin homeostasis by evaluating differences in skin phenotypes, functions, gene expression, and protein expression among WT, Vdr-R270L/H301Q (hereafter simply referred to as KI), and Vdr-KO (KO) rats. This evidence concerns the gene VDR and alopecia.