TheABCA4gene encodes an ATP-binding cassette transporter that is expressed specifically in the disc of photoreceptor outer segments. Mutations in theABCA4gene are the main cause of retinal degenerations known as “ABCA4-retinopathies.” Recent research has revealed thatABCA4is expressed in other cells as well, such as hair follicles and keratinocytes, although no information on its significance has been evidenced so far. In this study, we investigated the role of theABCA4gene in human keratinocytes and hair follicle stem cells for the first time. We have shown that silencing theABCA4gene increases the deleterious effect of all-trans-retinal on human hair follicle stem cells.