Given the positive relationship between the clonal expansion power of Tsc1-deficient cells and MG degeneration in the Tsc1-cko mouse retinas, we hypothesized that the Tsc1-deficient RPCs in Tsc1fl/fl;Tyrp1-Cre mouse retinas were likely to be too old, in mitotic terms, to preserve the survival program intact in their descendent MG. This evidence concerns the gene TYRP1 and myasthenia gravis.