The R555Q mutation occurred spontaneously and independently in the 2 unrelated CDB families and was confirmed to be transmitted to the next generation in 1 of the 2 families.
In our study, 5 previously reported mutations of the TGFBI gene - R124C, R124H, R124L (exon 4), R555W, R555Q (exon 12) - were analyzed using polymerase chain reaction followed by restriction digestion in 48 individuals from 19 unrelated families with different forms of corneal dystrophy from different regions of Ukraine.
Diagnoses included Thiel-Benhke CD (TBCD/R555Q) (13 eyes), classic granular CD (CGCD/R555W) (28 eyes), superficial variant of granular dystrophy (SVGD/R124 l) (27 eyes), lattice CD type I (LCDI/R124C) (20 eyes), Avellino CD (ACD/R124H) (2 eyes), H626R-lattice dystrophy (LCD/H626R) (6 eyes), and two novel dystrophies: a French variant of granular dystrophy (FVGD/R124 l+DT125-DE126) (9 eyes) and a French lattice CD type IIIA (LCDIIIA/A546T) (5 eyes).
Records of patients carrying this mutation were compared with those from three unrelated patients with corneal dystrophy of Bowman's layer (CDB) type 2 (R555Q mutation) and from three unrelated patients with classic corneal granular dystrophy (R555W mutation).