Aniridia

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Aniridia is an eye disorder that is characterized by a complete or partial absence of the colored part of the eye (the iris). Aniridia is typically present from birth (congenital) and affects both eyes. The pupils may also be abnormal or misshapen.

Genetic changes that cause disease are called pathogenic variants. Pathogenic variants in the PAX6 gene can cause aniridia. The PAX6 gene provides instructions for making a protein that is involved in the early development of the eyes, brain and spinal cord (central nervous system), and the pancreas. The PAX6 protein belongs to a group of proteins called transcription factors. These proteins bind to specific regions of DNA and regulates the activity of other genes. After birth, the PAX6 protein is found in many different eye structures, where it regulates gene activity.

Aniridia occurs in 1 in 40,000 to 100,000 newborns worldwide.

Aniridia is inherited in an autosomal dominant pattern, which means one copy of the altered gene in each cell is sufficient to cause the disorder. In approximately two-thirds of cases, a person with aniridia inherits the pathogenic variant from one affected parent. The remaining one-third of cases result from a new (de novo) variant in the gene that occurs during the formation of reproductive cells (eggs or sperm) in an affected individual's parent or during early embryonic development. These affected individuals typically have no history of the disorder in their family.

Published Date: April 09, 2026
Published By: National Institutes of Health