Anterior Segment Mesenchymal Dysgenesis

Clinical Characteristics
Ocular Features: 

The unique status of this entity remains to be established as there are overlapping features with aniridia (106210), and Peters anomaly (604229), posterior embryotoxon, and iridogoniodysgenesis type 1 (601631) and type 2 (137600).  Anterior segment mesenchymal dysgenesis itself is clinically heterogeneous even within families.  Schwalbe line is often anteriorly placed and there may be iris adhesions to the cornea, with or without corneal opacities.  Some patients have microcornea.  All layers of the cornea are dysplastic from the epithelium to the endothelium suggesting abnormal migration or function of neural crest cells.  Lens opacities are highly variable but they can be progressive. Curiously, elevated intraocular pressure is usually not present.  Visual acuity is highly variable with some patients having 20/20 vision and others bare hand motions depending on the degree of opacification of the lens and cornea.

Systemic Features: 

No systemic abnormalities are present.

Genetics

This is an autosomal dominant disorder secondary to mutations in either PITX3 (10q24.32) or FOXE3 (1p32)  which are both transcription factors.  The latter gene is also mutant in congenital primary aphakia (610256) and some cases of Peters anomaly (604229).

Another disorder of anterior segment dysgenesis and foveal hypoplasia (609218) has been described in a single family.  The likely transmission pattern (autosomal recessive) and the gene locus (16q23.2-24.2) suggest that it is a unique disorder but no mutation has been identified.

See also Anterior Segment Dysgenesis 6 (617315) and Anterior Segment Dysgenesis 8 (617319) for autosomal recessive conditions in which mutations result in malformations of the anterior chamber.

Treatment
Treatment Options: 

Cataract surgery is indicated in some cases and corneal transplantation has been attempted in a few individuals.

References
Article Title: 

References

Doucette L, Green J, Fernandez B, Johnson GJ, Parfrey P, Young TL. A novel, non-stop mutation in FOXE3 causes an autosomal dominant form of variable anterior segment dysgenesis including Peters anomaly. Eur J Hum Genet. 2011 Mar;19(3):293-9.

PubMedID: 21150893

Summers KM, Withers SJ, Gole GA, Piras S, Taylor PJ. Anterior segment mesenchymal dysgenesis in a large Australian family is associated with the recurrent 17 bp duplication in PITX3. Mol Vis. 2008;14:2010-5.

PubMedID: 18989383