X-Linked mental retardation

X-Linked Mental Retardation (XLMR) is a condition characterized by significantly below-average overall intellectual functioning and deficits in two or more adaptive behaviors before the age of 18. It is a genetic disorder that primarily affects males and is caused by mutations in genes on the X chromosome.

Etiology

XLMR is caused by mutations in genes on the X chromosome. The X chromosome is one of the two sex chromosomes in humans (the other is the Y chromosome). Males have one X and one Y chromosome (XY) and females have two X chromosomes (XX). Because males have only one X chromosome, a mutation in a gene on the X chromosome often results in a disease or condition. Females, on the other hand, have a second X chromosome that can often compensate for a mutation in the other.

Symptoms

The symptoms of XLMR vary greatly from person to person, even among members of the same family. The most common symptom is intellectual disability, which can range from mild to severe. Other symptoms can include learning disabilities, behavioral problems, and physical abnormalities.

Diagnosis

Diagnosis of XLMR is based on clinical findings and molecular genetic testing. Clinical findings can include intellectual disability and physical abnormalities. Molecular genetic testing can identify mutations in the genes on the X chromosome that cause XLMR.

Treatment

There is currently no cure for XLMR. Treatment is symptomatic and supportive, and can include educational support, behavioral therapy, and physical therapy.

Prognosis

The prognosis for individuals with XLMR varies greatly, depending on the severity of the intellectual disability and the presence of other symptoms and physical abnormalities. Some individuals with XLMR are able to live independently, while others require lifelong care and support.

See also

• Intellectual disability
• X chromosome
• Genetic disorder