Length-dependent toxicity of CTG repeats in different tissues.

Transgenic lines bearing the specific repeat lengths noted were outcrossed to driver gal4 lines that selectively express in specific tissues. Muscle expression was with 24B-gal4, neural expression with elav-gal4, and ubiquitous expression with da-gal4. Key: −, viable; +/−, semi-lethal; +, pupal lethal; ++, larval lethal.