ABCB11 deficiency-associated cholestasis can be sub-categorized based on mutation severity: FIC1/1 (p.Asp482Gly or p.Glu297Gly on both alleles), FIC1/3 (p.Asp482Gly or p.Glu297Gly on one allele; predicted protein-truncating mutation on second allele) and FIC3/3 (predicted protein-truncating mutation on both alleles). The gene discussed is ATP8B1; the disease is cholestasis.