Based on the increasing numbers of CD in WD, current American Association for the Study of Liver Diseases (AASLD) recommendations state that CD may be suspected when daily urinary copper excretion is low: <20 μg/24 h (<0.3 μmol/24 h) in patients treated with ZS or <100 μg/24 h (<1.6 μmol/24 h) on chelators and associated with low serum total copper and low Cp; however, cut-offs for serum copper and Cp are not provided [2]. The gene discussed is CP; the disease is Wilson disease.