Previous studies do include a negative study of ALS quadriceps biopsies from 30 patients [50] (the 26 quadriceps samples studied here were also negative), a study of 31 deltoid biopsies finding p62-immunoreactive, pTDP-43-negative foci in 25.8% of samples [2], and a case report of a c9ALS patient with blocky p62 inclusions in gastrocnemius [53]. This evidence concerns the gene SQSTM1 and amyotrophic lateral sclerosis.