Lessons learned in studies of rare diseases such as RP may be useful in other contexts in which neuroprotection could be beneficial (e.g., the use of proinsulin in combination with other therapies, including mutation-specific gene therapy), paving the way for broader use of proinsulin in the treatment of a range of more common conditions such as in glaucoma or the inflammaging brain. This evidence concerns the gene INS and glaucoma.