The Genetic Mysteries of the Corneal Dystrophies The Genetic ...

Lattice Dystrophy Type II• Associated with systemic amyloidosis• Deposition of amyloid in many tissues of the body• skin• arteries• sclera• peripheral nerves• Corneal changes occur later in life• Mutation localized to the gelsolin (GSN) gene onchromosome 9 (9q34)Lattice Dystrophy Type III and IIIALater Onset Lattice Dystrophies• Type III• Thick lattice lines extendingto the periphery• Occurs later in life• Inheritance pattern isautosomal recessive• No recurrent epithelialerosions• Mutation is on the TGFBIgene on chromosome 5-same site (5q31)• Type IIIA• Autosomal dominant• Recurrent epithelial erosions• Same phenotypicpresentation as Type III butdifferent mode of inheritanceand corneal erosionsProminent amyloid deposition posterior to Bowmans layerLattice Dystrophy Type IV• Another late-onset lattice dystrophy• Deep stromal opacities made of amyloid• Mutation localized to the TGFBI gene on chromosome 5(5q31)• The list of late-onset lattice dystrophies goes on and onand on…• Types V, VI and VII have been described, based on• the pattern of lattice lines• mutation sites and defective genes• pedigree11