Pigmentary glaucoma (PG) occurs when pigment from the back of the iris moves to the front part of the eye. This obscures one’s vision, and it can eventually cause blindness if it goes untreated. PG has a significant hereditary component, and males in their 20s and 30s are particularly at risk. Approximately 150,000 people in North America are living with PG, but until recently, scientists remained unsure of its cause. 

A 2019 study, conducted by scientists from the University of Alberta, Harvard University, and Flinders University, may have finally solved that mystery by isolating a gene with causative properties and behavior.* The results of this 2019 study represent a significant leap forward in our understanding of pigmentary glaucoma, including the ability to treat and, one day, prevent it.*

What they did

Using data from two separate families predisposed to PG, a protein sequencing technique was employed to identify the premelanosome protein (PMEL) gene as one associated with pigmentary glaucoma. PMEL is primarily expressed in the pigment cells of the skin and eyes. 

The researchers also identified seven more PG-related variants through the targeting screening of 394 additional participants, who were divided into three independent cohorts.  

What they found

Results revealed that five of the nine total variants demonstrated faulty processing of the PMEL protein, with the mutations causing significant changes to human cells. To investigate further, the team used gene-editing technology to introduce the mutations into zebrafish DNA. 

The outcome was positive: the fish’ pigmentation changed, and they developed eye defects with highly similar presentation to human glaucoma.

What it means

According to Michael Walter, professor and chair of medical genetics at the University of Alberta, this discovery leads the way to further research into the mechanisms through which genetic mutations result in pigmentary glaucoma. He also said that the study uncovered surprising similarities to several other neurodegenerative conditions, including Alzheimer’s.

“Some of the methods that are currently being used to think about treating Alzheimer’s might even be applied to treat glaucoma,” Walter stated. “It opens up awareness about other approaches we could take.”

*Neitz, R. (2019, Jan. 31). Scientists First to Pinpoint a Cause of Pigmentary Glaucoma. Medical Xpress. https://medicalxpress.com/news/2019-01-scientists-pigmentary-glaucoma.html

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