Clinical Characteristics
Ocular Features
One 4-generation Chinese family with 8 affected members has been reported. Complete bilateral iris defects were seen all patients who by 10 years of age also had cataracts. No corneal opacities were seen. Two patients were diagnosed with glaucoma. No fundus abnormalities were reported.
Systemic Features
No systemic abnormalities have been reported.
Genetics
Inheritance
Hereditary aniridia results from a dysfunction of the regulatory gene PAX6. In aniridia 1 (106210) the PAX6 gene (a transcription regulator) gene itself contains mutations. In anirdia 2 (617141) the mutation occurs in the ELP4 gene, whose product is a cis-regulatory enhancer of PAX6.
Aniridia 3 results from heterozygous mutations in the TRIM44 gene (11p13). The TRIM44 gene is a negative regulator which normally suppresses the expression of PAX6 and the reported missense mutation (p.G155R) enhances its activity.
Pedigree
Autosomal dominant
Autosomal dominant disorders require only one mutation for the disease to be expressed. Since an affected parent has two chromosomes, only one of which has the mutant gene, parents can expect that half (50%) of their children will receive that one and inherit the disease. It is common for individuals that inherit the mutation, however, to not have evidence of the disease (nonpenetrance).
Autosomal dominant inheritance leads to a vertical pattern of transmission