Article Text
Letters to JMG
New SMS mutation leads to a striking reduction in spermine synthase protein function and a severe form of Snyder–Robinson X-linked recessive mental retardation syndrome
Abstract
We report the identification of a novel mutation at a highly conserved residue within the N-terminal region of spermine synthase (SMS) in a second family with Snyder–Robinson X-linked mental retardation syndrome (OMIM 309583). This missense mutation, p.G56S, greatly reduces SMS activity and leads to severe epilepsy and cognitive impairment. Our findings contribute to a better delineation and expansion of the clinical spectrum of Snyder–Robinson syndrome, support the important role of the N-terminus in the function of the SMS protein, and provide further evidence for the importance of SMS activity in the development of intellectual processing and other aspects of human development.