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Aniridia and WAGR SyndromeA Guide for Patients and Their Families$
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Jill Ann Nerby and Jessca Otis

Print publication date: 2010

Print ISBN-13: 9780195389302

Published to Oxford Scholarship Online: November 2020

DOI: 10.1093/oso/9780195389302.001.0001

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PRINTED FROM OXFORD SCHOLARSHIP ONLINE (oxford.universitypressscholarship.com). (c) Copyright Oxford University Press, 2021. All Rights Reserved. An individual user may print out a PDF of a single chapter of a monograph in OSO for personal use. date: 07 March 2021

Aniridia—Epidemiology and Genetics

Aniridia—Epidemiology and Genetics

Chapter:
3 Aniridia—Epidemiology and Genetics
Source:
Aniridia and WAGR Syndrome
Author(s):

Anil K. Mandal

Harsha B. L. Rao

Publisher:
Oxford University Press
DOI:10.1093/oso/9780195389302.003.0007

Aniridia literally means “without iris.” The iris is the part of the eye that gives color to the eye. But the term aniridia encompasses more than its literal meaning and includes abnormalities of almost all the structures of the eye, from the cornea up to the optic nerve and including the angle of the anterior chamber, the lens, and the fovea. This is why aniridia is often called a “panocular disease.” The cornea is normally an avascular (lacking blood vessels), transparent tissue on the front part of the eye. In individuals with aniridia, it becomes vascularised. A bunch of blood vessels grows over the cornea: this growth is called a pannus. The angle of the anterior chamber is that part of the eye between the cornea and the iris that drains the fluid within the eye out of the eye and maintains the pressure within the eye at normal levels. Aniridia affects this part and hampers the fluid flow out of the eye, thereby increasing the pressure within the eye, leading to a condition called glaucoma. The lens is a biconvex structure behind the iris that focuses light rays entering into the eye onto the retina, which converts these light signals into electric signals that are carried through the optic nerve to the brain. In aniridia there may be displacement of the lens from its normal position, which is called subluxation or dislocation, or the normally clear lens may turn opaque, which is called a cataract. The fovea is the area of the retina that is responsible for clear vision. It may be underdeveloped; this is called foveal hypoplasia and affects vision. Similarly, the optic nerve that carries the visual sensations may also be underdeveloped, affecting vision. Besides these anatomical abnormalities, functional problems in addition to decreased vision include nystagmus (involuntary wobbling movement of the eye), squinting, and intolerance to light (photophobia). In this chapter we will discuss mainly the epidemiology (incidence and distribution of diseases) and genetic aspects of aniridia.

Keywords:   Anophthalmia, Bilateral partial iris hypoplasia, Cerebellar ataxia, Dominant inheritance, Ectopia lentis, FISH technique, Genetic counseling, Haploinsufficiency, Isolated aniridia, Karyotype analysis

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