It is unclear if the reduced hepatic IRE1α/XBP1 pathway expression seen in the pediatric cholestatic liver disease group is caused by the cholestasis and elicited only in end-stage liver disease, or whether these patients had an underlying genetic or developmental impairment of hepatic UPR activation which contributed to their progression to end-stage liver disease. This evidence concerns the gene XBP1 and End Stage Liver Disease.