real sister

Why Did Robin Trocki Leave Glee? Trocki had to be written off “Glee” because she has Alzheimer’s disease, which is common in people with Down syndrome. Is Jean from Glee dead in real life? Robin Trocki (June 30, 1956 – December 14, 2019) was an actress who portrayed Jean Sylvester, Sue’s older sister, on Glee.