The amount of a all-trans-retinol dehydrogenase [NAD(+)] ADH4 (human) when measured in blood. The trait is amount of all-trans-retinol dehydrogenase [NAD(+)] ADH4 (human) in blood (OBA_2052161). Also known as: blood all-trans-retinol dehydrogenase [NAD(+)] ADH4 (human) amount.