Snyder-Robinson Syndrome

National Organization for Rare Disorders, Inc.

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It is possible that the main title of the report Snyder-Robinson Syndrome is not the name you expected.

Disorder Subdivisions

  • None

General Discussion

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.

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.

Supporting Organizations

Snyder-Robinson Foundation

1443 Layman Street
McLean, VA 22101
Tel: 703-203-0215

For a Complete Report

This is an abstract of a report from the National Organization for Rare Disorders (NORD). For a full-text version of this report, go to and click on Rare Disease Database under "Rare Disease Information".

The information provided in this report is not intended for diagnostic purposes. It is provided for informational purposes only.

It is possible that the title of this topic is not the name you selected. Please check the Synonyms listing to find the alternate name(s) and Disorder Subdivision(s) covered by this report.

This disease entry is based upon medical information available through the date at the end of the topic. Since NORD's resources are limited, it is not possible to keep every entry in the Rare Disease Database completely current and accurate. Please check with the agencies listed in the Resources section for the most current information about this disorder.

Last Updated:  1/12/2016
Copyright  2016 National Organization for Rare Disorders, Inc.