The amount of a alpha-1,6-mannosylglycoprotein 6-beta-N-acetylglucosaminyltransferase A when measured in blood serum. The trait is level of alpha-1,6-mannosylglycoprotein 6-beta-N-acetylglucosaminyltransferase A in blood serum (OBA_2042362). Also known as: blood serum alpha-1,6-mannosylglycoprotein 6-beta-N-acetylglucosaminyltransferase A amount.