The ABCD1 (ATP-binding cassette subfamily D member 1) gene, located on the X chromosome (Xq28), encodes a peroxisomal transmembrane protein responsible for transporting very long-chain fatty acids (VLCFAs) into peroxisomes for β-oxidation. Widely expressed but particularly prominent in the brain, adrenal glands, and liver, ABCD1 is critical for maintaining lipid homeostasis. Mutations in ABCD1 cause X-linked adrenoleukodystrophy (X-ALD), a neurodegenerative disorder characterized by VLCFA accumulation, demyelination, adrenal insufficiency, and progressive neurological decline. Clinical manifestations vary widely, ranging from asymptomatic carriers to a severe, fatal childhood form. Primarily affecting males (with an estimated incidence of ~1 in 17,000 newborns), X-ALD has been included in newborn screening programs in many U.S. states ^[1-2]. The correlation between specific mutations and symptoms remains unclear, and VLCFA measurement cannot reliably predict disease-specific outcomes such as adrenal insufficiency or neurological decline. Current therapeutic approaches focus on gene repair or mitigating secondary effects like oxidative stress ^[3].

The Abcd1 KO mouse, a gene knockout model generated by deleting exon 2 of the mouse Abcd1 gene (homologous to human ABCD1), serves as a valuable tool for studying the pathogenesis of X-ALD and developing therapeutic interventions.