PTGDS and keratoconus: We replicated the same trend of MAF alteration of the association between the SNPs rs4894535 (FNDC3B, chr3: 171995605), rs7044529 (COL5A1, chr9: 137568051), rs11145951 (LCN12-PTGDS, chr9: 139860264) and rs2721051 (FOXO1, chr13: 41110884) and KC-risk as reported by a recently published GWAS.