Fragile X Syndrome: Causes, Symptoms, and Treatments

Fragile X syndrome is a hereditary condition which causes a wide range of mental problems, from mild learning disabilities to severe mental retardation. It is the most common cause of genetically-inherited mental problems. The full mutation appears in approximately 1 in 3600 males and 1 in 4000 to 6000 females. In addition to mental problems, fragile X syndrome is associated with a number of physical and behavioral characteristics.

The majority of males with fragile X syndrome will have major intellectual disabilities. In addition, males will have a variety of characteristics. Physical characteristics including enlarged ears and long face with prominent chin are common. Males with this syndrome also often have many ear infections, have flat feet, double-jointed fingers and have a variety of skeletal problems. Behavior in some males with fragile x syndrome includes attention deficit disorders, speech disturbances, hand biting, hand flapping, autistic behaviors and poor eye contact.

The characteristics seen in males are also presented in some females with fragile X syndrome. However, a smaller percentage of the females are affected and the degree of impact is usually smaller. This is because fragile x syndrome is a sex linked disorder. Females have two X chromosomes and males only have one. As a result, males with fragile X have only the malfunctioning gene. Females with fragile X have a normally functioning gene to partially compensate for the non functioning gene. Only about a third of the females have a significant mental disability. Others may have more moderate learning difficulties. The physical and behavioral features seen in males appear in a smaller percentage of females and usually are less severe.

A person with fragile X syndrome has a mutation in the FMR1 (fragile X mental retardation 1) gene in the DNA that makes up the X chromosome. That mutation causes the cell to turn off the FMR1 gene. Since the gene is turned off, the person doesn't make fragile X mental retardation protein (FMRP). That lack of a specific protein triggers fragile X syndrome.

At this time, there is no known cure for fragile X syndrome. However, special education, speech and language therapy, occupational therapy, and behavioral therapies are helpful in addressing many of the physical and behavioral impacts of fragile X syndrome. Also, medical intervention can be helpful for aggression, anxiety, hyperactivity and poor attention span. Because the impact of fragile X is so varied, it is important to do a careful evaluation of a person's strengths and weaknesses. That way, it is possible to create a treatment plan to address specific needs.

Sources:
"Fragile X Syndrome: Diagnostic and Carrier Testing." http://genetics.faseb.org/genetics/acmg/pol-16.htm

http://home.coqui.net/myrna/fragile.htm

The National Fragile X Foundation. http://www.fragilex.org/