ZEB1 and posterior polymorphous corneal dystrophy: Screening of the ZEB1 coding region in the 13 PPCD probands identified six nonsense mutations in the heterozygous state, of which five are novel: c.449delG (p.(Gly150Alafs*36)), c.689_690delAT (p.(His230Argfs*7)), c.1913_1914delCA (p.(Ser638Cysfs*5)), c.2650delC (p.(Gln884Argfs*37)), and c.3116_3117delAG (p.(Glu1039Glyfs*6)).