Abstract
Abstract: :
Purpose: Cornea plana is a rare stromal dystrophy that is inherited as either an autosomal dominant (CNA1), or a more severe autosomal recessive disease (CNA2). Both forms exhibit reduced corneal curvature with variable degree of hypermetropia, peripheral sclerisation of the cornea, indistinct limbal zone and shallow anterior chamber. Mutations in the keratocan gene have previously been described in CNA2 pedigrees. Our aim was to determine whether a mutation in this gene was implicated in a CNA2 family of Hispanic origin. Methods: A seven-member family with CNA2 was ascertained for linkage analysis and mutation detection. There are three affected children with two unaffected siblings from a consanguineous marriage. Informed consent was obtained prior to the collection of 20ml of peripheral blood from which DNA was extracted. The DNA from this family was amplified using PCR and the coding region of keratocan was sequenced. Sequencing was performed on an ABI 3100 automated sequencer using standard conditions. Results: The two coding exons of keratocan were sequenced and a base-pair change was identified in exon 2. This putative pathogenic change results in an amino acid substitution that occurs within the highly conserved leucine rich repeat (LRR) of keratocan. Conclusion: Other mutations in keratocan known to cause corneal plana are: Asn 247 Ser, Gln 147 Stop and Thr 215 Lys. These mutations and the one identified here all fall within the region encoding the LRR motifs of keratocan and possibly affect the tertiary structure of the protein.
Keywords: 374 cornea: stroma and keratocytes • 385 degenerations/dystrophies • 480 mutations