Fragile X Disorders

Fragile X-associated disorders (FXD) is a family of genetic conditions that can affect individuals in a variety of ways. The conditions are all caused by changes in the gene known as FMR1. Fragile X Syndrome (FXS) is caused by a full mutation of the FMR1 gene. Fragile X-associated tremor/ataxia syndrome (FXTAS) and Fragile X-associated primary ovarian insufficiency (FXPOI) are caused by a premutation of the FMR1 gene.

Learn about the prevalence of Fragile X mutations »

The Three Fragile X-Associated Disorders

Full Mutation

Fragile X Syndrome

FXS is a genetic condition caused by a full mutation of the FMR1 gene. Symptoms include intellectual disability, behavioral and learning challenges, and various physical characteristics.

Males are more frequently affected, and generally with greater severity.

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Premutations

Fragile X-Associated Tremor/Ataxia Syndrome

FXTAS is a genetic condition caused by a premutation of the FMR1 gene. Symptoms include balance, tremor, and memory problems and usually occurs after age 50, with symptoms worsening with age.

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Fragile X-Associated Primary Ovarian Insufficiency

FXPOI is a genetic condition caused by a premutation of the FMR1 gene. “Primary ovarian insufficiency” refers to a spectrum of impaired ovarian function that includes infertility and early menopause in women prior to the age of 40 years.

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Fragile X-associated disorders can be passed on by carriers of the FMR1 gene mutation who have no apparent signs of an FXD. In some families a number of individuals may be affected, while in other families a diagnosed individual may be the only known family member to exhibit symptoms. Also, in some families, only carriers are identified and there are no apparently affected family members.