There is little to support the designation of a corneal dystrophy as 'Avellino type' but it is included in this database because it is entrenched in the literature. It has features of both lattice dystrophy, type I, and granular dystrophy type I, which might be expected since all of these result from mutations in the same gene, TGFBI on chromosome 5. Not surprisingly, reported cases have clinical and histological features of both lattice and granular dystrophy and hence are labeled as having combined granular-lattice corneal dystrophy. There is considerable variation of the nature and quantity of the stromal deposits both within and among families, a common characteristic of autosomal dominant disorders. Even though clinical evidence may suggest primarily lattice or granular dystrophy, histological studies can reveal changes characteristic of both.
Early cases could be traced to the Avellino region of Italy from which the title was derived but more recent reports have described families from around the world.