AGBL5 and/or hyperglutamylation may therefore be targets for therapy in patients with defects in this gene, or other forms of retinal degeneration that involve changes in basal body or ciliary glutamylation levels, such as those with mutations in TTLL5, a tubulin glutamylase in which mutations cause cone-rod dystrophy. The gene discussed is TTLL5; the disease is retinal degeneration.