Deformability of the erythrocytes that cause the microcirculatory distress can be demonstrated through various other hemorheological characteristics. In order to determine the deformability of erythrocytes multiple factors including blood and plasma viscosity and hematocrit (a calculation of the percent of red blood cells present in the blood) are measured. Alpha-thalassemia
Alpha-thalassemia, like sickle cell trait, is typically inherited in areas with increased exposure to malaria. It manifests itself as a decreased expression of alpha-globin chains, causing an imbalance and excess of beta-globin chains, and can occasionally result in anemic symptoms. The abnormal hemoglobin can cause the body to destroy red blood cells, essentially causing anemia.In endurance-trained individuals with sickle cell trait the presence of alpha-thalassemia has been shown to act protectively against microvasculatory distress before, during, and after exercise. Signs, symptoms, and prevention
Because of the microcirculatory distress, a telltale sign or symptom of a potential sickling collapse is cramping. Specifically to sickle cell trait, cramping occurs in the lower extremities and back in athletes undergoing intense physical activity or exertion. In comparison to heat cramps, sickling cramps are less intense in terms of pain and have a weakness and fatigue associated with them, as opposed to tightly contracted muscles that lock up during heat cramps.A sickling collapse comes on slowly, following cramps, weakness, general body aches and fatigue.
Sudden deaths during physical exertion in African-American US army recruits, and athletes
Urinary tract infection

Suggested
Probable: complicated hyphema, venous thromboembolic events, fetal loss, neonatal deaths, and preeclampsia
Possible: acute chest syndrome, asymptomatic bacteriuria, and anemia in pregnancy
Insufficient evidence: retinopathy, cholelithiasis, priapism, leg ulcers, liver necrosis, avascular necrosis of the femoral head, and stroke. An association with complicated migraines has been suggested.There have been reports of pulmonary venous thromboembolism in pregnant women with sickle cell trait, or men during prolonged airflight, and mild strokes and abnormalities on PET scans in children with the trait.Sickle cell trait appears to worsen the complications seen in diabetes mellitus type 2 (retinopathy, nephropathy and proteinuria) and provoke hyperosmolar diabetic coma nephropathy, especially in male patients. Genetics
Normally, a person inherits two copies of the gene that produces beta-globin, a protein needed to produce normal hemoglobin (hemoglobin A, genotype AA). A person with sickle cell trait inherits one normal allele and one abnormal allele encoding hemoglobin S (hemoglobin genotype AS).The sickle cell trait can be used to demonstrate the concepts of co-dominance and incomplete dominance. An individual with the sickle cell trait shows incomplete dominance when the shape of the red blood cell is considered. This is because the sickling happens only at low oxygen concentrations. With regards to the actual concentration of hemoglobin in the circulating cells, the alleles demonstrate co-dominance as both normal and mutant forms co-exist in the bloodstream. Thus it is an ambiguous condition showing both incomplete dominance and co-dominance.Unlike the sickle-cell trait, sickle-cell disease is passed on in a recessive manner.