Muscle Dysfunction Caused by a K ATP Channel Mutation in Neonatal Diabetes Is Neuronal in Origin

Brain Over Muscle Mutations in the gene encoding the Kir6.2 subunit of the adenosine triphosphate (ATP)–sensitive potassium (K ATP ) channel cause a specific type of neonatal diabetes in humans, known as iDEND, which is often accompanied by muscle weakness of unknown etiology. By studying mice expressing the mutant gene only in muscle or only in nerve, Clark et al. (p. 458 , published online 1 July) found that the motor impairments originate from inappropriate activation of the channel in the central nervous system rather than in muscle. Patients with iDEND are often treated with sulphonylurea therapies that block K ATP channels in both brain and muscle, and these drugs can have adverse effects on heart muscle. Drugs with greater specificity for K ATP channels in the brain may thus be a safer option.