OMIM ID:
Corneal Dystrophy, Congenital Endothelial 2
Alternate Names
Defective Genes
Clinical Characteristics
Ocular Features
Corneal clouding is usually evident at birth and in virtually all cases in the first decade of life. Corneal edema is usually progressive and often leads to stromal scarring, neovascularization, and deposition of plaques eventually. The ground glass appearance of the cornea at least initially is most pronounced peripherally. When the ground glass appearance is present in young children, it may lead to the misdiagnosis of congenital glaucoma and some children have had glaucoma surgery. However, no anatomic abnormalities of the anterior chamber angle have been observed and glaucoma does not seem to occur in this disorder as it does in CHED1. Photophobia and tearing are uncommon.
The corneal epithelium may become atrophic with partial loss of Bowman’s membrane replaced by subepithelial fibrosis. Corneal sensitivity is normal. The stroma may have spheroidal degeneration resembling posterior polymorphous dystrophy. Generalized edema may lead to marked thickening of the entire cornea. The endothelium undergoes degeneration and cell loss is common, while those that remain often contain melanin granules. Descemet’s membrane is greatly thickened. This condition may be stable in some individuals while others clearly have evidence of progression, and a few have some regression in childhood. Vision may be quite good and few patients develop nystagmus.
Systemic Features
No systemic abnormalities have been reported.
Genetics
Inheritance
This is an autosomal recessive disorder resulting from mutations in the SLC4A11 gene located on chromosome 20 (20p13-12). This disorder must be distinguished from Harboyan syndrome (#217400, CDPD1) from which it differs by the absence of neurosensory deafness. The two disorders are allelic, however. A clinically similar but less severe and genetically distinct form of congenital endothelial dystrophy, CHED1 (121700), can have a later age of presentation, maps to a different region of chromosome 20 ( 20p11.2-q11.2), and is inherited in an autosomal dominant pattern.
Pedigree
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.