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The Prader-Willi Phenotype of Fragile X Syndrome

Nowicki, Stephen T. MD, PhD; Tassone, Flora PhD†§; Ono, Michele Y. MS; Ferranti, Jessica MD; Croquette, Marie Francoise MD; Goodlin-Jones, Beth PhD‡§; Hagerman, Randi J. MD

Journal of Developmental & Behavioral Pediatrics: April 2007 - Volume 28 - Issue 2 - p 133-138
doi: 10.1097/01.DBP.0000267563.18952.c9
Case Report

The Prader-Willi phenotype (PWP) of fragile X syndrome (FXS) is associated with obesity and hyperphagia similar to Prader-Willi syndrome (PWS), but without cytogenetic or methylation abnormalities at 15q11–13. Thirteen cases of PWP and FXS are reported here that were identified by obesity and hyperphagia. Delayed puberty was seen in 5 of 9 cases who had entered puberty, a small penis or testicles in seven of 13 cases, and infant hypotonia and/or a poor suck in seven of 13 cases. Autism spectrum disorder occurred in 10 of 13 cases, and autism was diagnosed in seven of 13 cases. We investigated cytoplasmic interacting FMR1 protein (CYFIP) expression, which is a protein that interacts with FMR1 protein (FMRP) because the gene for CYFIP is located at 15q11–13. CYFIP mRNA levels were significantly reduced in our patients with the PWP and FXS compared to individuals without FXS (p < .001) and also individuals with FXS without PWP (p = .03).

Departments of *Pediatrics, †Biochemistry and Molecular Medicine, and ‡Psychiatry and Behavioral Sciences, and §M.I.N.D. Institute, University of California at Davis Medical Center, Sacramento, California; ¶Department of Neuropediatrics, Centre Hospitalier Regional et Universitaire de Lille, France.

Received June 2006; accepted October 2006.

This study was supported by grants from the National Institute of Child Health & Development HD36071 and HD02274.

Address for reprints: Randi J. Hagerman, M.D., M.I.N.D. Institute, University of California at Davis Medical Center, 2825 50th Street, Sacramento, CA 95817; e-mail:

© 2007 Lippincott Williams & Wilkins, Inc.