Aniridia is a heterozygous disorder, meaning that only one of the two chromosome 11 copies is affected. When both copies are altered (homozygous condition), the result is a uniformly fatal condition with near complete failure of entire eye formation. In 2001, two cases of  homozygous aniridia patients were reported; the fetuses died prior to birth and had severe brain damage. In mice, homozygous small eye defect (mouse Pax-6) leads to loss of the eyes and nose and the murine fetuses sustain severe brain damage. Types
Aniridia may be broadly divided  into hereditary and sporadic forms. Hereditary aniridia is usually transmitted in an autosomal dominant manner (each offspring has a 50% chance of being affected), although rare autosomal recessive forms (such as Gillespie syndrome) have also been reported. Sporadic aniridia mutations may affect the WT1 region adjacent to the AN2 aniridia region, causing a kidney cancer called nephroblastoma (Wilms tumor). These patients often also have genitourinary abnormalities and intellectual disability (WAGR syndrome). Several different mutations may affect the PAX6 gene. Some mutations appear to inhibit gene function more than others, with subsequent variability in the severity of the disease. Thus, some aniridic individuals are only missing a relatively small amount of iris, do not have foveal hypoplasia, and retain relatively normal vision. Presumably, the genetic defect in these individuals causes less "heterozygous insufficiency," meaning they retain enough gene function to yield a milder phenotype.
Post-thrombotic syndrome (PTS), also called postphlebitic syndrome and venous stress disorder is a medical condition that may occur as a long-term complication of deep vein thrombosis (DVT). Signs and symptoms
Signs and symptoms of PTS in the leg may include:
pain (aching or cramping)
heaviness
itching or tingling
swelling (edema)
varicose veins
brownish or reddish skin discoloration
ulcerThese signs and symptoms may vary among patients and over time. With PTS, these symptoms typically are worse after walking or standing for long periods of time and improve with resting or elevating the leg.PTS lowers a persons quality of life after DVT, specifically with regards to physical and psychological symptoms and limitations in daily activities. Cause
Despite outgoing research, the cause of PTS is not entirely clear. Inflammation is thought to play a role as well as damage to the venous valves from the thrombus itself. This valvular incompetence combined with persistent venous obstruction from thrombus increases the pressure in veins and capillaries. Venous hypertension induces a rupture of small superficial veins, subcutaneous hemorrhage and an increase of tissue permeability. That is manifested by pain, swelling, discoloration, and even ulceration. Risk factors
The following factors increase the risk of developing PTS:
age > 65
proximal DVT
a second DVT in same leg as first DVT (recurrent ipsilateral DVT)
persistent DVT symptoms 1  month after DVT diagnosis
obesity
poor quality of anticoagulation control (i.e. dose too low) during the first 3 months of treatment

Diagnosis
When physicians find a DVT in the clinical history of their patients, a postthrombotic syndrome is possible if the patients have suggestive symptoms.