HTT and Huntington disease: An arbitrary sample of 60 proteins in the dataset was tested for the ability to modify an Htt-fragment-induced neurodegeneration phenotype in Drosophila. This polyQ toxicity model was generated using an N-terminal fragment of the human HD cDNA, encoding the first 336 amino acids of the protein, including a 128 Q expansion in exon 1 (see Materials and Methods).