Movement Disorder Linked to Faulty Gene
Syndrome Caused by Abnormal Gene May Lead to Balance Problems, Tremors, and Dementia Later in Life
Jan. 27, 2004 -- Men may be carrying a genetic mutation
responsible for a significant portion of the movement and mental difficulties
they encounter as they grow older.
A new study suggests that this genetic abnormality only becomes
apparent in men over 50 and can cause tremors, balance problems, and dementia
that become more severe with age.
Researchers say many of the adults that suffer from this
disorder, known as fragile X-associated tremor/ataxia syndrome (FXTAS), are
misdiagnosed with other age-related conditions such as Parkinson's and
"FXTAS may be one of the most common causes of tremor and
balance problems in the adult population, yet is being misdiagnosed because
neurologists who see adults with movement disorders are not aware that they
need to look for a family history of fragile X in grandchildren or to check for
the presence of the permutation in the fragile X gene," says researcher
Randi Hagerman, MD, medical director of the University of California, Davis
MIND Institute, in a news release.
What Is FXTAS?
FXTAS affects older men who carry a small mutation in the same
gene that causes fragile X syndrome, which is the most common cause of
inherited mental retardation.
In the study, published in the Jan. 28 issue of The Journal
of the American Medical Association, researchers looked at the prevalence
of tremor, balance disorders, and dementia among 192 families belonging to the
Northern or Southern California Fragile X Associations.
Researchers say nearly one in 800 men have this mutation in the
fragile X gene, and the study suggests that as many as 30% of these men may
develop FXTAS later in life.
The study showed that 17% of the men in their 50s had the
disorder, but the percentage of men with symptoms, such as tremors and balance
problems, increased dramatically with each decade of life. For example, 38% of
the men in their 60s, 47% of those in their 70s, and 75% of men in their 80s
had these symptoms.
Researchers say the majority of men with the genetic mutation
will develop at least mild symptoms of FXTAS.
Initial signs of the disorder in men may include difficulty
writing, walking, and using eating utensils and become more severe with age.
Other symptoms may include short-term memory loss, anxiety, loss of sensation,
and muscle weakness.
"FXTAS is an enigma," says Hagerman. "The disorder
appears later in life in men who are generally healthy throughout childhood and
early-to-mid-adulthood and have normal to above-normal intelligence, yet is
caused by a defect in a gene known to cause mental retardation usually
diagnosed in childhood."
Genetic Screening Urged
Researchers say the results show that screening for the genetic
mutation in the fragile X gene in men is important, especially if the person is
experiencing other symptoms of the disorder.
Counseling families of persons with the genetic mutation could
also help inform future generations who might inherit the defect.
Studies are under way to determine which drugs might be most
effective in relieving FXTAS-related symptoms.