PPCD is inherited in an autosomal dominant form and is genetically heterogeneous, with mutations identified in three loci: the chromosome 20p (20p 11.21) VSX1 gene mutation, characteristic of the PPCD1 subtype; the COL8A2 gene (1p34.2-p32. The gene discussed is OVOL2; the disease is posterior polymorphous corneal dystrophy.