The Genetics of Aniridia
Kelly Trout, RN, BSN
International WAGR Syndrome Association
In terms of inheritance, there are four basic "types" of aniridia. These are:
1) Familial aniridia
This is the most common form of aniridia. It is inherited directly from a parent
who has aniridia.
It is the result of a mutation in a gene called the “PAX6” gene.
In the past, genetic testing was thought to be unnecessary for those with familial
aniridia. Newer research has demonstrated that in some cases, familial aniridia
may be inherited through complex genetic abnormalities (such as translocations
or deletions) and that these abnormalities may result in serious conditions in the
offspring. For this reason, genetic analysis and counseling should be offered to
all individuals with aniridia.
Each child of a person with familial aniridia will have an approximate 50% chance
of inheriting the gene mutation.
2) Sporadic aniridia
This type of aniridia is the second most common form. Both parents have normal
The affected person has a “new” mutation of the PAX6 gene (a mutation which
occurred before or very soon after conception). The cause of this mutation is not
Children born with sporadic aniridia should be referred for genetic testing. This
testing should include high level studies (lymphocyte high resolution
chromosome study of at least 550 bands, and “FISH” studies) to determine
whether WAGR syndrome (see below) or other risk for Wilms tumor is present.
Children with sporadic aniridia should also be followed for the development of
Wilms tumor (a type of cancer of the kidney), regardless of the results of genetic
People with sporadic aniridia have an approximate 50% chance of passing on
this condition to their children.
3) WAGR Syndrome
This type of Aniridia is rare. Both parents have normal chromosomes.
The affected person has a “new” mutation (as in sporadic aniridia, above).
Unlike sporadic aniridia, this new mutation involves not only the PAX6 gene, but
a large number of neighboring genes as well. This genetic abnormality is called
a “deletion,” or set of missing genes, which are located on the short arm of
chromosome number 11.
High level genetic testing (lymphocyte high resolution chromosome study of at
least 550 bands, along with “FISH” studies) will reveal the WAGR deletion if it is
In addition to aniridia, children with WAGR syndrome have a high risk for Wilms
tumor (a type of cancer of the kidney) and other conditions, such as genital
abnormalities, cognitive impairment, and learning and behavior difficulties.
There has been a single report of two cases of WAGR syndrome occurring within
a family. Genetic testing will help parents determine their own risk for having
another child with WAGR syndrome.
To date, there have been no reports of people with WAGR syndrome having
children of their own.
4) Gillespie Syndrome
This type of aniridia is extremely rare. It is thought that Gillespie syndrome may
be inherited through parents who do not have aniridia themselves, but who both
have one normal copy of the PAX6 gene, and one mutated copy. This mode of
inheritance has not been confirmed.
Gillespie syndrome is associated with a “scalloped border” appearance of the iris.
Learning difficulties, cognitive impairment, and cerebellar ataxia, (muscle
incoordination) are also associated with Gillespie syndrome.
There are reports of more than one case of Gillespie syndrome in a family. There
have also been reports of people with Gillespie syndrome whose children also
have the disorder.
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Last reviewed: March, 2009