LGALS4 and retinal degeneration: Consistent with this, we found that transheterozygosity for strong (null) alleles of both genes enhanced α-synuclein-induced retinal degeneration (Ptp4E1, Ptp10D1/ +; Rh1-Gal4 / +; UAS-α-synuclein / +); whereas heterozygosity for either allele in isolation showed no significant enhancement (Fig. 5b and Additional file 2: Figure S5).