Small Copy Number-Neutral Intrachromosomal Translocation of PAX6 and Aniridia

Background

Classic aniridia is a rare, usually inherited eye disorder characterized by partial or near-complete absence of the iris. Although the name refers to the iris, the condition often affects multiple parts of the eye, including the cornea, lens, retina, and optic nerve. Many patients experience reduced vision, light sensitivity, nystagmus, cataracts, glaucoma, and other complications that can worsen over time.

In most classic cases, aniridia is linked to changes involving the PAX6 gene, a key developmental gene that helps guide formation of the eye and other tissues. A person can have an abnormal PAX6 protein, or the gene may be structurally altered so that it can no longer be expressed properly. Importantly, not all disease-causing changes are simple sequence variants. Some are structural variants, such as deletions, duplications, inversions, or translocations. These can be difficult to detect with standard testing, especially when the overall amount of DNA is unchanged.