Quantitative differentiation of benign and misfolded glaucoma- causing myocilin variants on the basis of protein thermal stability

Accurate predictions of the pathogenicity of mutations associated with genetic diseases are key to the success of precision medicine. Inherited missense mutations in the myocilin (MYOC) gene, within its olfactomedin (OLF) domain, constitute the strongest genetic link to primary open-angle glaucoma via a toxic gain of function, and thus MYOC is an attractive precision-medicine target. However, not all mutations in MYOC cause glaucoma, and common variants are expected to be neutral polymorphisms. The Genome Aggregation Database (gnomAD) lists-100 missense variants documented within OLF, all of which are relatively rare (allele frequency <0.001%) and nearly all are of unknown pathogenicity. To distinguish disease-causing OLF variants from benign OLF variants, we first characterized the most prevalent population-based variants using a suite of cellular and biophysical assays, and identified two variants with features of aggregation-prone familial disease variants. Next, we considered all available biochemical and clinical data to demonstrate that pathogenic and benign variants can be differentiated statistically based on a single metric: the thermal stability of OLF. Our results motivate genotyping MYOC in patients for clinical monitoring of this widespread, painless and irreversible ocular disease.

Automated summary

Accurate prediction of the pathogenicity of mutations associated with genetic diseases is crucial for the success of precision medicine. In this study, missense mutations in the MYOC gene's olfactomedin domain were investigated to determine the disease-causing variants from benign ones. Through cellular and biophysical assays, followed by analysis of biochemical and clinical data, the thermal stability of the olfactomedin domain was found to be a statistically significant metric for distinguishing pathogenic variants. These findings suggest the potential for clinical monitoring of glaucoma through genotyping of the MYOC gene.