Selective death of motor neurons beginning in mid life is the hallmark of the most abundant motor-neuron disease of adults, amyotrophic lateral sclerosis (ALS). An unexpected insight into potential causes of the disorder is now provided by mice lacking the hypoxia response element of the promoter of the gene encoding the vascular endothelial cell growth factor (VEGF). This elicits age-dependent, selective degeneration of motor neurons, and indicates that a primary cause of ALS may be chronic deficits in VEGF-dependent vascular perfusion or a direct neurotrophic effect of VEGF on motor neurons.
