We analyzed the effect of 13CRA on the mRNA levels of the peroxisomal ABC transporters (ABCD1, ABCD2, ABCD3) and HPRT (for normalization) in isolated CD14+ monocytes, CD19+ B cells and the T cell-enriched PBMC fraction remaining after depletion of the CD14+ and CD19+ cells (approximately 75% T cells) of acne patients receiving 13CRA therapy. This evidence concerns the gene ABCD1 and acne.