If you quitclaim a property for less than the property value it will be considered as a gift and you may have to pay gift tax for that amount if it does not cross the gift tax exemption limit.
Gift tax exemption limit for individual per year is $12000. But lifetime exemption limit is $250000. For married couple, if they file together, then lifetime gift tax exemption limit is $500000. Gift tax is generally paid by the grantor but not by the grantee.