FMR1 Gene

Fragile X-associated primary ovarian insufficiency (FXPOI) is a condition that affects women and is characterized by reduced function of the ovaries. The ovaries are the female reproductive organs in which egg cells are produced. As a form of primary ovarian insufficiency, FXPOI can cause irregular menstrual cycles, early menopause, an inability to have children (infertility), and elevated levels of a hormone known as follicle stimulating hormone (FSH). FSH is produced in both males and females and helps regulate the development of reproductive cells (eggs in females and sperm in males). In females, the level of FSH rises and falls, but overall it increases as a woman ages. In younger women, elevated levels may indicate early menopause and fertility problems.

The severity of FXPOI is variable. The most severely affected women have overt POI (formerly called premature ovarian failure). These women have irregular or absent menstrual periods and elevated FSH levels before age 40. Overt POI often causes infertility. Other women have occult POI; they have normal menstrual periods but reduced fertility, and they may have elevated levels of FSH (in which case, it is called biochemical POI). The reduction in ovarian function caused by FXPOI results in low levels of the hormone estrogen, which leads to many of the common signs and symptoms of menopause, such as hot flashes, insomnia, and thinning of the bones (osteoporosis). Women with FXPOI undergo menopause an average of 5 years earlier than women without the condition.

Fragile X syndrome is a genetic condition that causes a range of developmental problems including learning disabilities and cognitive impairment. Usually, males are more severely affected by this disorder than females.

Affected individuals usually have delayed development of speech and language by age 2. Most males with fragile X syndrome have mild to moderate intellectual disability, while about one-third of affected females are intellectually disabled. Children with fragile X syndrome may also have anxiety and hyperactive behavior such as fidgeting or impulsive actions. They may have attention deficit disorder (ADD), which includes an impaired ability to maintain attention and difficulty focusing on specific tasks. About one-third of individuals with fragile X syndrome have features of autism spectrum disorder that affect communication and social interaction. Seizures occur in about 15 percent of males and about 5 percent of females with fragile X syndrome.

Most males and about half of females with fragile X syndrome have characteristic physical features that become more apparent with age. These features include a long and narrow face, large ears, a prominent jaw and forehead, unusually flexible fingers, flat feet, and in males, enlarged testicles (macroorchidism) after puberty.

Fragile X-associated tremor/ataxia syndrome (FXTAS) is characterized by problems with movement and thinking ability (cognition). FXTAS is a late-onset disorder, usually occurring after age 50, and its signs and symptoms worsen with age. This condition affects males more frequently and severely than females. Affected individuals have areas of damage in the part of the brain that controls movement (the cerebellum) and in a type of brain tissue known as white matter, which can be seen with magnetic resonance imaging (MRI). This damage leads to the movement problems and other impairments associated with FXTAS.

The characteristic features of FXTAS are intention tremor, which is trembling or shaking of a limb when trying to perform a voluntary movement such as reaching for an object, and problems with coordination and balance (ataxia). Typically, intention tremors will develop first, followed a few years later by ataxia, although not everyone with FXTAS has both features. Many affected individuals develop other movement problems, such as a pattern of movement abnormalities known as parkinsonism, which includes tremors when not moving (resting tremor), rigidity, and unusually slow movement (bradykinesia). In addition, affected individuals may have reduced sensation, numbness or tingling, pain, or muscle weakness in the lower limbs (peripheral neuropathy). Some people with FXTAS experience problems with the autonomic nervous system, which controls involuntary body functions, leading to the inability to control the bladder or bowel.

People with FXTAS commonly have cognitive disabilities. They may develop short-term memory loss and loss of executive function, which is the ability to plan and implement actions and develop problem-solving strategies. Loss of this function impairs skills such as impulse control, self-monitoring, focusing attention appropriately, and cognitive flexibility. Many people with FXTAS experience anxiety, depression, moodiness, or irritability.

Some women develop immune system disorders, such as hypothyroidism or fibromyalgia, before the signs and symptoms of FXTAS appear.