The ability of these mutants to make some levels of VLC-PUFAs, which may be sufficient to preserve retinal structure (9, 17, 18), may explain why SCA34 patients do not have any reported retinal degeneration compared to STGD3 patients in which the STGD3 mutant ELOVL4 lacks VLC-PUFA biosynthesis. This evidence concerns the gene ELOVL4 and retinal degeneration.