By studying rodent models of the relatively rare inherited form of Lou Gehrig’s disease and tissue samples from a patient with the condition, scientists have discovered the first evidence that damage to nerve cell powerhouses is directly responsible for these cells’ death. The findings appear in the July 9 issue of Neuron.The research team from the University of California San Diego, Johns Hopkins and elsewhere discovered that dysfunctional proteins clog the transport system that brings vital substances into mitochondria, the tiny organelles that provide energy to cells. This mitochondrial damage occurs in muscle-controlling nerve cells, the researchers report, helping explain the selective nature of inherited amyotrophic lateral sclerosis (ALS), or Lou Gehrig’s disease.