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

Accurate predictions of pathogenicity for mutations associated with genetic disease are key to the success of precision medicine. Inherited, missense coding mutations in the myocilin gene (MYOC), within its olfactomedin (OLF) domain, comprise the strongest genetic link to primary open angle glaucoma via a toxic gain of function, and 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 gnomAD database 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 disambiguate disease from benign OLF variants, we first characterized the most prevalent population-based variants using a suite of cellular and biophysical assays, and identify two variants with features of aggregation-prone familial disease variants. Next, we consider all available biochemical and clinical data to demonstrate that pathogenic and benign variants can be differentiated statistically based on a single metric, thermal stability of OLF. Our results motivate genotyping MYOC in patients for clinical monitoring of this widespread, painless, and irreversible age-onset disease.