OMIM ID:
Peters Anomaly
Defective Genes
Clinical Characteristics
Ocular Features
Peters anomaly occurs as an isolated malformation but also as a feature of other syndromes. It is often unilateral. A wide variety of other ocular findings may occur with Peters anomaly as well. Here we limit our description to ‘simple’ Peters anomaly in which the findings are limited to the eye having the classic findings of adhesions of the iris to the posterior cornea and a central or paracentral corneal leukoma. The lens may also be adherent to the cornea and is often opacified to some degree. Descemet’s membrane and portions of the posterior stroma are usually missing as well. Glaucoma is frequently present. Importantly, there is a wide range in the presentation of clinical features.
Systemic Features
Peters anomaly is a frequent feature of numerous syndromes, both ocular and systemic, among them the Peters-plus (261540) syndrome (sometimes called the Kivlin-Krause (261540) syndrome) and has been reported in a case with aniridia (106210).
Genetics
Inheritance
Isolated Peters anomaly usually occurs in an autosomal recessive pattern but autosomal dominant patterns have been reported as well. The recessive disorder may be caused by a mutation in several genes, notably PAX6, PITX2, CYP1B1, FOXC1, and FOXE3. The latter gene is also mutated in anterior segment mesenchymal dysgenesis (107250) and congenital primary aphakia (610256). The variety of clinical features are likely the result of a disruption in some common pathway or pathways. Mutations in B3GALTL associated with the Peters-Plus syndrome have not been identified in isolated Peters anomaly.
This is a genetically and clinically heterogeneity condition as whole genome sequencing reveals numerous additional gene mutations in patients with both syndromic and isolated Peters anomaly.
PITX2 is also mutated in ring dermoid of the cornea (180550) and in Axenfeld-Rieger syndrome type 1 (180500). PAX6 mutations also cause diseases of the cornea, fovea, optic nerve and iris.
Pedigree
Autosomal dominant
Autosomal dominant disorders require only one mutation for the disease to be expressed. Since an affected parent has two chromosomes, only one of which has the mutant gene, parents can expect that half (50%) of their children will receive that one and inherit the disease. It is common for individuals that inherit the mutation, however, to not have evidence of the disease (nonpenetrance).
Autosomal dominant inheritance leads to a vertical pattern of transmission
Autosomal recessive
In order for autosomal recessive disorders to be expressed, offspring generally must inherit two mutations, one from each carrier parent. Carriers with only one mutation, such as the parents, do not have clinical disease. Note that carrier parents can expect that 1 in 4 children (25%) will inherit both mutations and have the disorder, 2 in 4 children (50%) will be carriers like their parents, while 1 in 4 children (25%) inherit neither mutation.
In order for autosomal recessive disorders to be expressed, offspring generally must inherit two mutations, one from each carrier parent. Carriers with only one mutation, such as the parents, do not have clinical disease. Note that carrier parents can expect that 1 in 4 children (25%) will inherit both mutations and have the disorder, 2 in 4 children (50%) will be carriers like their parents, while 1 in 4 children (25%) inherit neither mutation.