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.
An implicit equation in Cartesian coordinates for a torus radially symmetric about the z-axis is

or the solution of f(x, y, z) = 0, where

Algebraically eliminating the square root gives a quartic equation,

The three classes of standard tori correspond to the three possible aspect ratios between R and r:

When R > r, the surface will be the familiar ring torus or anchor ring. R = r corresponds to the horn torus, which in effect is a torus with no "hole". R < r describes the self-intersecting spindle torus; its inner shell is a lemon and its outer shell is an apple
When R = 0, the torus degenerates to the sphere.When R ≥ r, the interior

of this torus is diffeomorphic (and, hence, homeomorphic) to a product of a Euclidean open disk and a circle. The volume of this solid torus and the surface area of its torus are easily computed using Pappuss centroid theorem, giving:
These formulas are the same as for a cylinder of length 2πR and radius r, obtained from cutting the tube along the plane of a small circle, and unrolling it by straightening out (rectifying) the line running around the center of the tube. The losses in surface area and volume on the inner side of the tube exactly cancel out the gains on the outer side.