In a study aiming to understand the role of lipid synthesis in retina development and diseases such as retinitis pigmentosa (as photoreceptors shed 10% of their outer segment daily and need to synthesize membrane discs rapidly; Young, 1967), we made an unexpected discovery that the lipogenic transcription factor sterol regulatory element binding protein 2 (SREBP2; also known as SREBF2) has a function in eye size regulation. The gene discussed is SREBF2; the disease is retinitis pigmentosa.