Citrullinemia type II accompanied by mental derangement combined with multidrug resistance 3 decrease, case report

Background: Here we report a rare case of citrullinemia type II (CTLN2) accompanied by mental derangement with a deficiency of multidrug resistance 3 (MDR3) in the liver.Case presentation: The clinical data of a 17-year-old girl were collected. Liver puncture was performed, and hepatic expression of MDR3 was determined by immunohistochemistry. Serum amino acids of the patient and her parents wwere determined by a chemical isotope labeling liquid chromatography-mass spectrometry (CIL LC-MS). Genetic mutations of ABCB4 and SLC25A13 were screened by whole-exome sequencing. Immunohistochemical analysis showed a remarkably lower expression of MDR3. Mutation in ABCB4 gene was not found and whole-exome sequencing revealed the SLC25A13 mutation 852-855 del. Elevated serum levels of citrulline, homocitrulline, and homoarginine in the patient and her mother were found.Conclusions: We reported a rare case of CTLN2 combined with MDR3 deficiency, without mutation of ABCB4. The link between MDR3 down-expression and CTLN2 warrants further investigation. Meanwhile, clinicians need to further rule out the possibility of CTLN2 if MDR3 decreases in adolescent patients with mental disorders and abnormal liver function.