KRAS and laryngotracheoesophageal cleft: The mechanism for the decreased serum Zn level in HCV-related LC is presumed to involve the non-structural (NS) proteins 3 (NS3, Zn-containing enzyme) and NS5A (Zn metalloprotein) of HCV, but the serum Zn concentration itself may not be affected by the HCV genotype and HCV viral load [43,44,45,46].