A myocilin Gln368STOP homozygote does not exhibit a more severe glaucoma phenotype than heterozygous cases

Purpose: To describe the phenotype of an individual homozygous for the common Gln368STOP myocilin mutation and to discuss the other family members.

Design: Cascade screening was performed for Australian families that had been identified as having the myocilin Gln368STOP mutation.

Methods: Recruited subjects underwent comprehensive clinical examination and mutation analysis for the Gln368STOP myocilin mutation by direct sequencing.

Results: One 49-year-old woman was found to be homozygous for the mutation. Her maximal recorded intraocular pressure was 17 mm Hg. Bilateral optic disk examination revealed small, healthy optic discs. Automated perimetry testing was normal.

Conclusions: Neither the individual homozygous for the Gln368STOP myocilin mutation nor her younger heterozygous siblings displayed any signs suggestive of glaucoma. One of the two heterozygous parents did manifest glaucoma. Although there is the possibility of the homozygous individual developing glaucoma in the future, she does not manifest a phenotype that is more severe than usual.