Corneal amyloidosis caused by Leu518Pro mutation of beta ig-h3 gene

Aim-To report a Japanese family diagnosed clinically as having lattice corn eal dystrophy type I (LCDI) in which a Leu518Pro mutation in the beta ig-h3 gene and not the R124C mutation reported previously was found. Methods-Molecular genetic analysis was performed on DNA extracted from peri pheral leucocytes from four members (three affected and one unaffected) of a family. Exon 4 of the beta ig-h3 gene was amplified by PCR and directly s equenced. Histopathological study was performed on the corneal tissue from the proband obtained during deep lamellar keratoplasty. Results-All the affected members were clinically diagnosed as having LCDI, and the pedigree indicated an autosomal dominant inheritance. A heterozygou s single base pair transition (CTG to CCG, leucine to proline) was detected in codon 518 of the beta ig-h3 gene in the three affected members, and not in the unaffected member. No mutation was found in codon 124. Amyloid depo sits were observed between the collagen bundles of the corneal stroma and w ere seen to extend deep into the stroma. Conclusion-The Leu518Pro mutated beta ig-h3 forms amyloidogeneic intermedia tes which precipitate in the cornea and gives rise to a clinical appearance of LCDI.