NAXE and Leukoencephalopathy: Whole exome sequencing revealed defects in the APOA1BP gene, also known as NAXE gene, which produces apolipoprotein A-I-binding protein catalyzing the epimerization of the S- and R-forms of NAD(P)HX in apolipoprotein A-I.[1] Impairment of the APOA1BP gene results in cholesterol metabolism disorders and causes progressive early onset encephalopathy with brain edema and/or leukoencephalopathy.[1]