Identifying genes that cause severe eye malformations
Study of Severe Eye Malformation.
“Our aim is to identify genes that cause serious eye malformations. Finding such genes will help improve our understanding of how these disorders occur.”
Our research group at the MRC Human Genetics Unit in Edinburgh have identified changes in genes called SOX2, OTX2 and PAX6 that cause a proportion of severe eye malformations. These genes are involved both in the out-pouching of the early brain and the formation of the lens. About 20% of children with anophthalmia or severe microphthalmia will have a tiny genetic change in one of these genes. We are now extending our studies of these and other genes that act in the developing eye to improve our understanding of these conditions.
This knowledge may eventually help in the management and treatment of these conditions. Our research can also help understand how these genes function normally in human development. We are keen to recruit new cases affected with:
- Anophthalmia (absent eye)
- Microphthalmia (small eye),
- Coloboma (6 o'clock defect in iris, retina or optic nerve)
- Other related eye malformations are birth defects that are caused by an abnormality in the early development of the eye.
The eye begins developing in the early embryo at 28 days after fertilisation (equivalent to six weeks of pregnancy) as an out-pouching of both sides of the brain called the optic vesicle. The optic vesicle grows and makes contact with the surface of the embryonic face, this contact produces a surface thickening called a placode that subsequently forms the lens of the eye. The out-pouching then changes shape to form the optic cup ultimately forming a hollow sphere with a space containing the lens at the front and a gap along the bottom called the optic fissure.
The optic fissure must then fuse to form a normal eye, failure of this step will cause coloboma which can involve the light collecting inner surface of the eye (the retina), the nerve carrying the visual information (the optic nerve) and/or the tissue surrounding the pupil (the iris). Failure of any of the processes involved in early eye development may cause anophthalmia and/or microphthalmia. In most cases the cause of these problems is not known.