Identification of the GLC1F Gene in Primary Open Angle Glaucoma

Abstract

Purpose: : To identify the gene responsible for primary open angle glaucoma (POAG) in the GLC1F family.

Methods: : All 42 genes in the GLC1F region were sequenced in affected GLC1F members and controls. After identification of a synonymous mutation all exons were sequenced in 256 POAG unrelated patients and 559 controls. This study was conducted in accordance with tenets of the Declaration of Helsinki. Informed consent was obtained from all participants. Total RNA was isolated from confluent cells from trabecular meshwork (TM), heart and skeletal muscle (SM) using TRIzol reagent (Invitrogen) according to the manufacturer’s instructions. Primary cell cultures and paraffin-embedded sections were probed with mouse monoclonal antibody against variants 1 and 2 and rabbit polyclonal antibodies to fibronectin or tenascin C.

Results: : After screening all 42 genes in the GLC1F region, a synonymous mutation (T270T) was identified in all affected family members. Screening of 256 unrelated POAG patients identified 11 nonsynonymous variants in 17 individuals. None of these changes with the exception of R304C were found in the 559 controls that were screened. This gene was expressed in TM, heart and skeletal muscle in at least two different spliced forms. Immunohistochemical staining showed expression of the gene in the juxtacanalicular region and inner and outer walls of Schlemm’s canal. The protein colocalized with fibronectin and tenascin C but not with fibrillins-1 and -2 or tropoelastin.

Conclusions: : Mutations in this gene result in POAG in the GLC1F family and in 6.6% of the POAG population. Protein expression in the TM is consistent with this protein being involved in POAG pathogenesis.

Keywords: genetics • trabecular meshwork • mutations