Beneficial effect of ursodeoxycholic acid in patients with acyl‐CoA oxidase 2 (ACOX2) deficiency–associated hypertransaminasemia

Abstract Background and Aims: A variant (p.Arg225Trp) of peroxisomal acyl‐CoA oxidase 2 (ACOX2), involved in bile acid (BA) side‐chain shortening, has been associated with unexplained persistent hypertransaminasemia and accumulation of C27‐BAs, mainly 3α,7α,12α‐trihydroxy‐5β‐cholestanoic acid (THCA). We aimed to investigate the prevalence of ACOX2 deficiency‐associated hypertransaminasemia (ADAH), its response to ursodeoxycholic acid (UDCA), elucidate its pathophysiological mechanism and identify other inborn errors that could cause this alteration. Methods and Results: Among 33 patients with unexplained hypertransaminasemia from 11 hospitals and 13