ACOX2 and hyperinsulinemic hypoglycemia, familial, 4: Interestingly, ACOX2 (acyl-CoA oxidase-2) deficiency, an inborn error of cholesterol metabolism, like CTX can present with ataxia [36], but unlike CTX shows elevated levels in serum/plasma of C27 acids with unusual 25S-stereochemistry [37], including 3β,7α-dihydroxycholest-5-en-(25S)26-oic acid, the 25S-epimer of 3β,7α-diHCA, which has recently been shown to be less neuroprotective than the 25R-epimer [30].