ABCD1 and metabolic disease: Furthermore, C4BPA and IL-26 are immune-related complement system genes and inflammation-related factors, respectively, and it has been suggested that the deletion of exon 2 of ABCD1 could affect the nonspecific complement system or immune-inflammatory system due to demyelination of neurons (Gupta et al., 2021) or metabolic disorder of immune factors (Swaminathan et al., 2022) in some patients with ALD.