MECP2 duplication syndrome

MECP2 duplication syndrome is an inherited disorder that occurs almost exclusively in males. Symptoms of this syndrome include moderate to severe intellectual disability, weak muscle tone, feeding difficulties, poor or absent speech, seizures, muscle stiffness, and recurrent respiratory tract infections. Children with MECP2 duplication syndrome have slow development of motor skills such as sitting and walking, or loss of previously acquired skills. About half of affected males die before the age of 25 years, mostly from complications of recurrent respiratory infections and/or neurologic deterioration. There is no specific treatment available but medical surveillance and care may help to improve some symptoms and overall condition of life. MECP2 duplication syndrome is caused by the duplication of genetic material on a specific region on the X chromosome that includes a gene named MECP2.

MECP2 duplication syndrome is inherited in an X-Linked recessive manner. This type of inheritance requires the presence of one copy of a pathogenic variant, in this case a duplication, in the gene located on the X-chromosome for males to be affected. When the pathogenic variant is inherited from the unaffected carrier mother, the male child will have the genetic disease. There is a 50% chance that a baby will inherit the pathogenic variant from the mother; females who inherit the pathogenic variant will be carriers, males who inherit the pathogenic variant will be affected.

Females who carry the duplication of MECP2 usually do not have signs and symptoms of MECP2 duplication syndrome because the X chromosome that contains the duplication may be turned off (inactive) due to a developmental process called X-inactivation.

The prevalence of MECP2 duplication syndrome is unknown, but 120 affected individuals have been reported in the scientific literature. This condition is estimated to be responsible for 1 to 2 percent of all cases of intellectual disability caused by changes in the X chromosome.

Genetic Home Reference: MECP2 duplication syndrome (http://ghr.nlm.nih.gov/)
MECP2 Duplication Syndrome (http://www.mecp2duplication.com/cms/)

OMIM: [Mental retardation, X-linked syndromic, Lubs type: 300260] (http://www.ncbi.nlm.nih.gov/omim)
GeneReview: [MECP2 duplication syndrome] (http://www.ncbi.nlm.nih.gov/books/NBK1116/)

• Copy number analysis: exons 2, 3 & 4