Fragile X syndrome (FXS) is the most common inherited cause of mental retardation. It is also one of the most common identifiable causes of Autism Spectrum Disorder (ASD). Carriers of FXS are often considered to be cognitively and behaviorally unaffected. However, we report here on six individuals in the premutation range who also have ASD. A comparison is made with five subjects in the premutation range who did not receive a diagnosis of ASD. The six individuals with ASD had a range of cognitive ability levels from no impairment to moderate retardation. Discussion includes the impact of molecular variables including lowered FMR1 protein and elevated FMR1 mRNA in addition to environmental factors leading to the complex neurodevelopmental disorder of ASD.
1M.I.N.D. Institute, Department of Psychiatry and Behavioral Sciences, UCDHS, Sacramento
2Department of Biological Chemistry, University of California, Davis, Davis
3M.I.N.D. Institute, Sacramento
4M.I.N.D. Institute, Department of Pediatrics, UCDHS, Sacramento, California
Received August 2003; accepted September 2004.
Address for reprints: Beth Goodlin-Jones, Ph.D., M.I.N.D. Institute, UC Davis Medical Center, 2825 50th Street, Sacramento, CA 95817; e-mail: firstname.lastname@example.org.