Keratoconus--no association with the transforming growth factor beta-induced gene in a cohort of American patients.

Abstract

Keratoconus is a noninflammatory, corneal thinning disorder leading to mixed myopic and irregular astigmatism and implicated as a major reason for cornea transplantations in the Western world. Genetic factors have been suggested as a cause of keratoconus. The levels of transforming growth factor beta-induced (TGFBI) protein have been reported to be altered in keratoconus tissues. Mutations in this gene are responsible for causing various corneal dystrophies. Given this strong evidence of the involvement of this gene in corneal dystrophies, we investigated possible mutations within this gene in 15 probands of families with keratoconus. All patients and control individuals had complete ophthalmological examination by a corneal specialist to determine their affectation status. The entire transcript of the TGFBI gene was analyzed by direct sequencing from patient DNA. We found 8 sequence variations within the gene, none of which was protein-altering changes. These changes were also observed in control individuals, and 4 are previously known polymorphisms. We concluded that the TGFBI gene is not responsible for causing keratoconus in these patients.