To begin systematically characterizing gene functions, we generated loss-of-function mutations for each of the 100 fly gene orthologs of the prioritized candidate AD risk genes, using CRISPR genome editing to insert a T2A-GAL4 (Figure 1B) or Kozak-GAL4 (Figure 1C) cassette at each gene locus40,41. The gene discussed is LGALS4; the disease is Alzheimer disease.