The amount of a endoplasmic reticulum mannosyl-oligosaccharide 1,2-alpha-mannosidase when measured in blood serum. The trait is level of endoplasmic reticulum mannosyl-oligosaccharide 1,2-alpha-mannosidase in blood serum (OBA_2042276). Also known as: blood serum endoplasmic reticulum mannosyl-oligosaccharide 1,2-alpha-mannosidase amount.