OMIM ID:
Corneal Dystrophy, Reis-Bücklers
Alternate Names
Defective Genes
Clinical Characteristics
Ocular Features
This is an anterior corneal dystrophy involving the epithelium and Bowman membrane. Opacities consisting of spots and lines form in the central portion of the anterior cornea creating haziness with relative sparring of the periphery. These can be seen as early as 4-5 years of age but few symptoms occur until the epithelium breaks down causing painful corneal erosions. Visual acuity eventually drops as the corneal haze increases along with increasing irregularity of the epithelial surface.
Ultrastructural studies reveal degenerative changes in all epithelial cells and almost complete Bowman membrane replacement with disoriented collagen fibrils.
A comparative histological study of Reis-Bücklers and Thiel-Behnke dystrophies concluded that these are distinct CDB (corneal dystrophy Bowman) disorders and suggested the former be called CDB type I, and the latter CDB type II. Type II is considered unique on the basis of the ‘curly’ fibers seen in the Bowman and subepithelial layers, while type I has bandshaped granular Masson-positive subepithelial deposits and ‘rod-shaped bodies’ resembling granular dystrophy. Type I described here generally leads to greater vision loss than type II.
Systemic Features
No systemic disease is associated with Reis-Bücklers corneal dystrophy.
Genetics
Inheritance
This disorder seems to be closely related to the more common Thiel-Behnke dystrophy as the corneal disease is caused in both cases by missense mutations in the TGFBI gene on chromosome 5 (5q31). The mutation in Reis-Bücklers results in a p.Arg124Leu amino acid substitution whereas most cases of Thiel-Behnke dystrophy are the result of a p. Arg555Gln substitution. Both disorders are inherited in an autosomal dominant pattern.
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