NEFL and amyotrophic lateral sclerosis: In situ hybridization revealed a consistent reduction in NF-L mRNA levels in degenerating spinal motoneurons of ALS patients (Tomkins et al., 1998; Al-Chalabi et al., 1999; Wong et al., 2000), while NF-L deficiency accelerates motoneuron degeneration in transgenic mice (Xu et al., 1993), indicating the importance of NF protein stoichiometry in the distribution and aggregation of NFs.