Homozygous mutations in MFN2 cause multiple symmetric lipomatosis associated with neuropathy

Multiple symmetric lipomatosis (MSL) is a mitochondrial disorder with impaired brown fat metabolism that has been associated with MERRF mutations in some, but not all, patients. We studied a sibling pair and an unrelated indiviadual who presented with MSL and neuropathy to determine the genetic etiology of this disorder in patients who did not carry the MSL-associated MERRF mutation. Whole-exome sequencing was performed on the siblings, and a rare, shared homozygous mutationinMFN2(c.2119C>T:p.R707W)wasidentified.Themutationwasnotpresentintheirhealthysiblings.Insilicoprograms