Intractable Rare Dis Res. 2016;5(4):255-261. (DOI: 10.5582/irdr.2016.01082)

The neurobiology of the Prader-Willi phenotype of fragile X syndrome.

Muzar Z, Lozano R, Kolevzon A, Hagerman RJ


Fragile X syndrome (FXS) is the most common inherited cause of intellectual disability and autism, caused by a CGG expansion to greater than 200 repeats in the promoter region of FMR1 on the bottom of the X chromosome. A subgroup of individuals with FXS experience hyperphagia, lack of satiation after meals and severe obesity, this subgroup is referred to have the Prader-Willi phenotype of FXS. Prader-Willi syndrome is one of the most common genetic severe obesity disorders known and it is caused by the lack of the paternal 15q11-13 region. Affected individuals suffer from hyperphagia, lack of satiation, intellectual disability, and behavioral problems. Children with fragile X syndrome Prader-Willi phenotye and those with Prader Willi syndrome have clinical and molecular similarities reviewed here which will impact new treatment options for both disorders.

KEYWORDS: Fragile X syndrome (FXS), Prader-Willi phenotype, FMR1 gene, Hyperphagia, Autism, IGF-1, Growth hormone

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