Very low levels of full-length HML-2 Env protein are further supported by our complete failure to detect any full-length HML-2 Env signal by Western blotting of bulk brain or spinal cord tissue lysates of ALS patients or controls, despite very strong signal seen with 2102Ep whole cell lysates having the same total protein concentration. Here, ERVW-1 is linked to amyotrophic lateral sclerosis.