Nature Communications 6: Article number: 6228 (2015); Published 4 March 2015; Updated 12 May 2015

This Article incorrectly cites reference 30 at the end of the third sentence of the third paragraph of the Discussion: ‘However, knockout of Mfsd2a does not lead to retinal degeneration30.’ The correct citation is as follows:

Tang, T. et al. A mouse knockout library for secreted and transmembrane proteins. Nat. Biotechnol. 28, 749–755 (2010).