Keratoconus is a non-inflammatory corneal thinning disorder and the major cause of cornea transplantations in Western countries. Despite intensive investigations, the underlying cellular and molecular mechanisms of keratoconus remain poorly understood. Although it has been suggested that mutations in VSX1 and SOD1 may contribute to disease presentation in some cases, the contribution of these genes to keratoconus status is controversial. In 2011, linkage analysis in an affected Irish pedigree led to identification of a mutation in the seed region of MIR184 (+57C>T) as the putative cause of keratoconus in the pedigree. In a subsequent screening of 790 patients of European or Indian descent, two novel causative mutations (+3A>G, +8C>A) in MIR184 were identified. Notably, mutations in MIR184 have recently been reported in two pedigrees, each affected with ocular diseases that affect the cornea. MiRNA 184 is the most abundant miRNA in the cornea.

Forty seven unrelated Iranians affected with keratoconus were recruited. Keratoconus was diagnosed based on clinical indications during slit-lamp biomicroscopy, refraction and fundus examination. DNA was extracted from peripheral leukocytes of these patients and MIR184 was screened for mutations by direct Sanger sequencing.

Only one variant allele (+39G>T; rs41280052) was observed in one patient. The same variation has previously been observed in control and keratoconus affected individuals at similar frequencies, suggesting that it is not a cause of keratoconus.

Although the sample size was small, it is evident that mutations in MIR184 are not a common cause of keratoconus among Iranian patients. No mutations were observed among the 94 chromosomes of the patients screened.