ABCA12 encodes an ATP-binding cassette transporter that plays critical roles in skin barrier function and lipid homeostasis. The protein transports lipids, particularly glucosylceramides, from the outer to inner leaflet of lamellar granule membranes in keratinocytes, facilitating lipid lamellae formation in the stratum corneum essential for epidermal barrier function 1. ABCA12 also regulates keratinocyte differentiation and desquamation by transporting lamellar granule-associated proteolytic enzymes 1. The upper hair follicle forms a functioning barrier through ABCA12, and barrier disruption in this region affects epidermal responses and impairs sebum release 1. Loss-of-function mutations in ABCA12 cause autosomal recessive congenital ichthyosis, with biallelic loss-of-function mutations typically resulting in the severe harlequin ichthyosis phenotype, while missense mutations generally lead to milder forms like congenital ichthyosiform erythroderma or lamellar ichthyosis 2. Beyond dermatological functions, ABCA12 has been implicated in cancer stem cell biology, where it maintains stemness and chemoresistance by reducing intracellular ceramide levels 3, and recent studies suggest potential roles in autism neurobiology through effects on lipid homeostasis and neuroinflammation 4.