A Preliminary Study on Gene Mutation and its Function in a Large Family (GZ.1 Pedigree) with Open–A\ngle Glaucoma

Abstract

Purpose: : To determine the causative mutation of myocilin gene and to investigate its pathogenic function in a large Chinese pedigree (GZ.1) with familial open–angle glaucoma.

Methods: : Genome–wide scanning was performed and the Lod scores were calculated. Candidate gene was amplified and screened for mutations using direct sequencing. To elucidate its expression, distribution and cytotoxicity of mutant myocilin, HTM cells were transfected with pcDNA–wild–type and mutant myocilin vectors using liposomes.

Results: : Mutation analysis of the myocilin gene showed a C–to–T transition at the 1,109th nucleotide in exon 3 resulting in a change of amino acid from proline to leucine (Pro370Leu). This mutation cosegregated with all affected individuals (16/16) and it was not present in unaffected individuals (0/8). In transfected HTM cells, the mutant myocilin protein was not correctly processed in ER and accumulated as aggresome–like structures in the cytoplasma instead of secretion. In addition, the expression of the mutant protein also led to cell apoptosis.

Conclusions: : The mutation of Pro370Leu in myocilin gene could cause the accumulation of misfolding myocilin protein in HTM cells, which might lead to glaucoma in GZ.1 pedigree.

Keywords: genetics • gene screening • gene transfer/gene therapy