Axenfeld-Rieger Syndrome

Question 1

What is Axenfeld’s anomaly?

Answer 1

1. Posterior embryotoxon - anterior displacement of Schwalbe’s line anterior to the limbus in the cornea
2. Iris strands adherent to the anteriorly displaced Schwalbe’s line

Question 2

What is Rieger anomaly?

Answer 2

Iris abnormalities including:

1. Iris hypoplasia (can see sphincter muscle through anterior surface of iris)
2. Corectopia
3. Polycoria

Question 3

What is Rieger syndrome? What is Axenfeld-Rieger syndrome?

Answer 3

Rieger syndrome = Rieger anomaly + systemic findings related to impaired differentiation or migration of neural crest cells (dental, facial bone defects including maxillary hypoplasia, umbilical abnormalities, pituitary involvement)

Axenfeld-Rieger syndrome = Axenfeld anomaly + Rieger syndrome

Question 4

Mutations in what genes are associated with ARS?

Answer 4

PITX2
FOXC1
PAX6
FOXO1A

Question 5

What is the histologic finding in ARS?

Answer 5

A monolayer of endothelial-like cells with a descemet-like membrane extending from the cornea across the anterior chamber and angle structures onto the surface of the iris

Question 6

How often is glaucoma seen in ARS, why does it occur, and when does it present?

Answer 6

1. 50% of cases
2. Neural crest cells that have undergone developmental arrest are retained in the AC during gestation leading to incomplete development of the TM/SC
3. Most cases occur in adolescence or early adulthood