Conditions such as reduced corneal thickness, are observed in people with cases of polycoria, as well as keratoconus (keratoconus is a corneal disease has the possibility of leading to blindness and/or astigmatism). However, there are some proposals that it is caused by a dissociation of the pupil margins, a partial coloboma which is a hole in the eye, or abnormal eye tissue composition. Causes
There is not any known direct mechanisms involved in the development of true polycoria or pseudopolycoria. There are some proposed ideas, one being that after the sphincter muscle is fully formed and developed in the eye there is a severing of the pupillary margins leading to the distinction of the extra pupil and the principal pupil. Polycoria can also be caused any hole in ones iris to develop a sphincter muscle development. Another proposed theory about the cause of polycoria is intrauterine trauma, or postpartum iris trauma.If the development of the iris is hindered, the ectoderm of the eye (which forms the lens and corneal epithelium) may split, which could lead to pseudopolycoria. Genetics
The gene that is the cause of this disorder is the PRDM5 gene. The PRDM5 gene has also been linked to Brittle Cornea syndrome, which is a tissue disorder of the eye, as well as Axenfeld syndome. PRDM5 plays crucial roles in the molecular composition of the eye, as well as the tissue thickness. Axenfeld syndrome occurs in the patient in a case of the mutation of the FOXC1 gene, which is a heterozygous mutation.
Before pregnancy
Genetic testing and counselling are available to help determine the risk of passing the condition onto a child. This may involve testing a sample of tissue or blood to look for signs of the genetic mutation that causes haemophilia. During pregnancy
A pregnant woman with a history of haemophilia in her family can test for the haemophilia gene. Such tests include:

chorionic villus sampling (CVS): a small sample of the placenta is removed from the womb and tested for the haemophilia gene, usually during weeks 11–14 of pregnancy
amniocentesis: a sample of amniotic fluid is taken for testing, usually during weeks 15–20 of pregnancyThere is a small risk of these procedures causing problems such as miscarriage or premature labour, so the woman may discuss this with the doctor in charge of her care. After birth
If haemophilia is suspected after a child has been born, a blood test can usually confirm the diagnosis. Blood from the umbilical cord can be tested at birth if theres a family history of haemophilia. A blood test will also be able to identify whether a child has haemophilia A or B, and how severe it is. Classification
There are several types of haemophilia: haemophilia A, haemophilia B, haemophilia C, parahaemophilia, acquired haemophilia A, and acquired haemophilia B.Haemophilia A is a recessive X-linked genetic disorder resulting in a deficiency of functional clotting Factor VIII. Haemophilia B is also a recessive X-linked genetic disorder involving a lack of functional clotting Factor IX.