Abstract
Purpose: :
To evaluate the suggested role of the COL8A1 and COL8A2 genes in the pathogenesis of corneal ectasias such as keratoconus and keratoglobus, through mutation screening in affected patients.
Methods: :
DNA extraction, PCR amplification and sequencing of COL8A1 and COL8A2 were performed in 36 unrelated keratoconus and 2 unrelated keratoglobus patients.
Results: :
No sequence variations were identified in COL8A1 and COL8A2 in the two patients with keratoglobus. Screening patients with keratoconus revealed a single sequence variant in COL8A1: c.1850C>T (Pro535Pro), in one patient. Four previously described single nucleotide polymorphisms (SNPs) were identified in COL8A2: c.112G>A (Ala35Ala) in 5 patients; c.1308G>A (Arg434His) in 1 patient; c.1492G>A (Gly495Gly) in 5 patients; and c.1765C>T (Pro586Pro) in 1 patient. Two novel sequence variants were also identified in a single affected individual each: c.52–54dupGCT and c.2026C>T (Val673Val).
Conclusions: :
Although COL8A1 and COL8A2 knockout mice develop corneal ectasia, most closely resembling keratoglobus, screening of these genes in patients with keratoconus and keratoglobus reveals only a single keratoconic patient with a possible pathogenic sequence variant in COL8A2 (c.52–54dupGCT). While further investigations of the possible association of c.52–54dupGCT with keratoconus are ongoing in this family, COL8A1 and COL8A2 do not appear to be associated with keratoconus or keratoglobus in any of the other affected individuals that were screened.
Keywords: gene screening • keratoconus • mutations