IMPG1 and age-related macular degeneration: Other protein coding genes up regulated in AMD include glyceraldehyde-3-phosphate dehydrogenase, nuclear ubiquitous casein and cyclin-dependent kinase substrate 1(NUCKS1), glutathione S-transferase alpha 4 (GSTA4) and interphotoreceptor matrix proteoglycan-1 (IMPG1), a gene encoding the Sialoprotein associated with cones and rods (SPACR)33.