TGFBI and granular corneal dystrophy type II: Granular corneal dystrophy type 2 (GCD2, also called Avellino corneal dystrophy) is an autosomal dominant disorder caused by an arginine-to-histidine substitution at codon 124 (R124H) of the transforming growth factor β-induced gene (TGFBI) on chromosome 5q31.8.