As ubiquitous or pan-neuronal knockdown of Drosophila Usp12 results in no identifiable phenotypes26, the exacerbated loss of photoreceptor neurons in the HD transgenic flies can be attributed to a specific effect of Usp12 on mHTT-associated neurodegeneration, rather than an adverse effect of Usp12 loss of function in neuronal cells. This evidence concerns the gene USP12 and Huntington disease.