A 4-month-old girl is referred because she ‘has no coloured part’ in either eye and is very sensitive to light. Both eyes appear dark with barely visible iris tissue. She startles to light but visual behaviour is difficult to assess. She is otherwise healthy with normal growth.
Examination Findings
Bilateral near-total aniridia — only a small iris stump is visible on gonioscopy. Horizontal pendular nystagmus. Corneas clear (no keratopathy yet). Lenses appear normal. Dilated fundus shows foveal hypoplasia with absent foveal reflex. Pressures normal on palpation. No Wilms tumour signs; abdomen soft with no palpable mass.
Investigations
Genetic testing for PAX6 and, crucially, for a contiguous deletion involving WT1 on chromosome 11p13 — the WAGR association. Renal ultrasound surveillance is arranged while genetics is pending, because Wilms tumour risk cannot wait for the laboratory. Baseline glaucoma workup (pressure, disc, corneal diameter) and refraction; cataract and keratopathy develop over time.
Questions to Think About
- Why does sporadic (non-familial) aniridia trigger a renal ultrasound?
- What are the lifelong eye threats in aniridia beyond the missing iris?
- How do you counsel parents who ask ‘will our next child have this?’
Diagnosis
Bilateral congenital aniridia — for WAGR exclusion and lifelong ocular surveillance.
Reasoning
The diagnosis is bilateral congenital aniridia, and the immediate question is whether it is isolated (PAX6 mutation, autosomal dominant) or part of WAGR syndrome — a contiguous deletion on 11p13 that removes both PAX6 and the adjacent WT1 tumour-suppressor gene. Sporadic aniridia carries the WAGR risk; familial aniridia with an affected parent essentially excludes it. Because Wilms tumour typically appears before age 5, renal ultrasound surveillance starts now and repeats at intervals through early childhood while genetic testing is pending — this is the sight-and-life-saving step that must not wait. The eyes need lifelong care for a cascade of problems: aniridia-associated keratopathy (limbal stem-cell failure clouding the cornea), cataract, and glaucoma, which is common and often refractory. Nystagmus and foveal hypoplasia limit acuity and need low-vision support from the start. Counselling: isolated PAX6 aniridia is autosomal dominant (50% recurrence); a de novo case still warrants testing the parents; WAGR deletions are usually de novo with low sibling recurrence but the affected child needs tumour surveillance and developmental monitoring.
Differential Diagnosis
- Congenital aniridia (PAX6-related) — fits: bilateral near-total iris absence with nystagmus and foveal hypoplasia.
- WAGR syndrome — must be excluded in every sporadic aniridia: Wilms tumour, aniridia, genitourinary anomalies, developmental delay from an 11p13 deletion including WT1.
- Gillespie syndrome — considered: aniridia with cerebellar ataxia and intellectual disability; no ataxia here.
- Traumatic iris loss — ruled out: bilateral, congenital, no trauma history.
- Iris coloboma — ruled out: coloboma is a sectoral defect, not near-total absence.
Management
Urgent genetics: PAX6 testing plus 11p13 deletion analysis for WT1. Renal ultrasound surveillance through early childhood until WAGR is excluded (and ongoing if confirmed). Lifelong eye follow-up for keratopathy, cataract, and glaucoma; low-vision support for nystagmus and foveal hypoplasia; photophobia management (tinted lenses, brimmed hats). Paediatric review for genitourinary and developmental features if WAGR is confirmed.
Key Learning Points
- Every sporadic aniridia needs WAGR exclusion: 11p13 deletion involving WT1 brings Wilms tumour risk — renal ultrasound surveillance starts immediately.
- Aniridia is a pan-ocular disease: keratopathy, cataract, and glaucoma threaten vision lifelong, not just the missing iris.
- Isolated PAX6 aniridia is autosomal dominant; WAGR deletions are usually de novo — genetics sets the counselling.
Red Flags
- Sporadic aniridia without renal imaging — Wilms tumour must be actively excluded
- Abdominal mass or haematuria in early childhood — Wilms tumour until proven otherwise
- Rising pressure or enlarging cornea — aniridic glaucoma is common and aggressive
- Progressive corneal haze — aniridia-associated keratopathy, refer early
Educational content only — not medical advice. Clinical decisions must be made by a qualified professional for the individual patient.
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