Infantile onset CMT2D/dSMA V in monozygotic twins due to a mutation in the anticodon-binding domain of GARS

Mutations in the GARS gene cause Charcot-Marie-Tooth 2D and distal spinal muscular atrophy type V allelic disorders characterized by predominantly distal upper extremity weakness and atrophy, typically beginning during the second decade of life. We report monozygotic twin girls with onset of weakness in infancy and a previously reported GARS mutation within the anticodon-binding domain. The severity and remarkable similarity in phenotypes of these girls and the reported case suggest that mutations within the anticodon-binding domain are more damaging to aminoacyl tRNA synthetase function than those within other domains of GARS.