Here, we demonstrated that distinct clinical phenotypes of X‐ALD are associated with increased levels of transcriptional inhibitors of myelin gene expression (ie, ID4 and SOX2) and the resulting decreased levels of genes associated with the mature differentiated phenotype (ie, MBP, MOBP, MOG, MAG, NINJ2, OPALIN, OLIG1, CNP and PLP1). The gene discussed is NINJ2; the disease is X-linked adrenoleukodystrophy.