Gene variants were retrieved from peer-reviewed articles by searching the PubMed database (https://www.ncbi.nlm.nih.gov/pubmed) using the following search string: [gene name] AND [cholestasis] (where [gene name] was either VPS33B, VIPAS39, MYO5B, AP1S1 or SCYL1). Here, SCYL1 is linked to cholestasis.