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


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.

Learn more about FXS »


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.

Learn more about FXTAS »

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.

Learn more about FXPOI »

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.

Learn More

Genetics & Inheritance

Even for genetics professionals, FMR1 inheritance is complex and confusing.

Learn more »

Signs & Symptoms

The signs and symptoms of the three Fragile X disorders.

Learn more »


How often does a Fragile X premutation or full mutation occur? Here’s what we know.

Learn more about prevalence »

Testing & Diagnosis

In the 1990s, scientists identified the FMR1 gene that causes FXS and accurate DNA testing became available.

Learn more »

Premutation Carriers

When you or a family member are told you are a “carrier” for a Fragile X mutation, many questions arise.

Learn more »

31 Shareable Fragile X Facts

For National Fragile X Awareness Month, we shared one fact a day for each day of the month, had printable posters, and more.

Read 31 Shareable Fragile X Facts »