NORD gratefully acknowledges Charles E. Schwartz, Ph.D, Director of Research, Greenwood Genetic Center, for the preparation of this report.
Snyder-Robinson syndrome (SRS) is a rare x-linked intellectual disability (XLID) disorder in which affected males have a slender build with long limbs, angular profile, and prominent muscles or bones (asthenic habitus), low muscle mass, some abnormal facial features (dysmorphism), speech abnormalities, outward curvature and lateral curvature of the spine (kyphoscoliosis) and decreased bone mass leading to fragile bones (osteoporosis). Seizures are also not uncommon. The syndrome results from an inactivating mutation in the spermine synthase gene resulting in an inability to convert spermidine to spermine.Introduction
Snyder-Robinson syndrome was first described in a single family by Snyder and Robinson in 1969. In 2003 Cason and colleagues determined that SRS resulted from a mutation in the spermine synthase (SMS) gene located at Xp21.3-p22.12. Since then, utilization of biochemical analysis (lack of SMS activity, altered spermidine/spermine ratio) to validate SMS mutations has allowed the identification of an additional ten families with SRS.
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