Role of BIGH3 R124H mutation in the diagnosis of Avellino corneal dystrophy.

PURPOSE: To report the presence of the R124H mutation in two Spanish families with Avellino corneal dystrophy (ACD).
METHODS: Two families with subjects who presented biomicroscopic features of ACD were included in this study. They have no relatives of Italian origin. Genomic DNA of the patients was isolated from peripheral blood. DNA was amplified using primer pairs corresponding to exons 4 and 12.
RESULTS: In Family 1, Patients I-1, II-1, and II-3 presented granular deposits in the anterior stroma. In Family 2, Patients I-1 and II-1 presented similar deposits in anterior stroma; Patient I-2 presented biomicroscopic findings similar to granular corneal dystrophy (GCD) and isolated fine lattice deposits. Patient II-2 presented isolated central granular deposits and remarkable lattice deposits in the form of Christmas tree. An identical point mutation in the BIGH3 gene (TGFBI) was observed in all affected members of the two families. The mutation consisted of a substitution of arginine by histidine at amino acid residue 124. It was reflected in the sequence analysis by the presence of a G to A transition at nucleotide 418. The mutation was not found in unaffected family members.
CONCLUSIONS: The detection of the R124H BIGH3 mutation confirmed the diagnosis of ACD in the reported families. This is the first study that shows the presence of such mutation in Spain. The authors found the same mutation reported in other countries. In earlier stages, BIGH3 mutation analysis may help to distinguish ACD from GCD, particularly in young patients.