UBL4A and amyotrophic lateral sclerosis: It is tempting to speculate that partial loss-of-function mutations or haplo-insufficiency in one or more of the human TRC pathway components (WRB, CAML, TRC40/ASNA1, TRC35, Ubl4A, Bag-6/Bat-3/Scythe) may in the future be found to be causative in inherited cases of ALS or other motor neuron disease.