Fragile X-associated Disorders

The term Fragile X-associated Disorders (FXD) refers to a family of conditions all caused by changes in the same gene. The gene’s scientific name is “FMR1,” but it is commonly referred to as “the Fragile X gene.” At this time we know of three distinct Fragile X-associated Disorders, but research is ongoing to evaluate other, perhaps more subtle effects of changes in the Fragile X gene that may have implications for a person’s health.

Fragile X syndrome (FXS)

The most common inherited cause of intellectual disabilities, fragile X syndrome occurs in both males and females, though females generally have less severe symptoms. FXS can cause developmental and language delays, learning impairment, and behavioral and mental health issues. Individuals with FXS have a form of the Fragile X gene called a “full mutation.”

Fragile X-associated primary ovarian insufficiency (FXPOI)

FXPOI can cause infertility, early menopause and other ovarian problems in women of reproductive age who are Fragile X “carriers.” Carriers have a form of the Fragile X gene called a “premutation.”        

Fragile X-associated tremor/ataxia syndrome (FXTAS )

FXTAS is an adult onset (over age 50) neurological condition that can cause balance and memory problems, tremors and other neurological and psychiatric symptoms in Fragile X carriers. It is more common in males than females. Like FXPOI, FXTAS is also caused by a Fragile X premutation.

In some families only one of these conditions may occur, while in others, all three conditions can occur in related family members.

Contributed by: Liane Abrams, MS, CGC