Codocytes (target cells) are the most common RBC morphologies encountered in the double heterozygous state known as hemoglobin SC disease (HbSC) . HbSC red blood cells are often dehydrated and become xerocytes (cells that have their hemoglobin pooled to one side-half moon cells). Some HbSC red blood cells crystallize as they dehydrate and attempt to take on both the sickle shape and the shape of hemoglobin C crystals (top image). This dual hemoglobin crystal can have many unique shapes. A HbSC crystal is indicated by the arrow in the bottom image on the right.
