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Genetics Home Reference: your guide to understanding genetic conditions     A service of the U.S. National Library of Medicine®

PPM-X syndrome

Reviewed October 2011

What is PPM-X syndrome?

PPM-X syndrome is a condition characterized by psychotic disorders (most commonly bipolar disorder), a pattern of movement abnormalities known as parkinsonism, and mild to severe intellectual disability. Other symptoms include increased muscle tone and exaggerated reflexes. Affected males may have enlarged testes (macro-orchidism). Not all affected individuals have all these symptoms, but most have intellectual disability. Males with this condition are typically more severely affected than females, who usually have only mild intellectual disability.

How common is PPM-X syndrome?

The prevalence of PPM-X syndrome is unknown.

What genes are related to PPM-X syndrome?

Mutations in the MECP2 gene cause PPM-X syndrome. The MECP2 gene provides instructions for making a protein called MeCP2 that is critical for normal brain function. Researchers believe that this protein has several functions, including regulating other genes in the brain by switching them off when they are not needed. The MeCP2 protein likely plays a role in maintaining connections (synapses) between nerve cells. The MeCP2 protein may also control the production of different versions of certain proteins in nerve cells. Although mutations in the MECP2 gene disrupt the normal function of nerve cells, it is unclear how these mutations lead to the signs and symptoms of PPM-X syndrome.

Some MECP2 gene mutations that cause PPM-X syndrome disrupt attachment (binding) of the MeCP2 protein to DNA, and other mutations alter the 3-dimensional shape of the protein. These mutations lead to the production of a MeCP2 protein that cannot properly interact with DNA or other proteins and so cannot control the expression of genes. It is unclear how MECP2 gene mutations lead to the signs and symptoms of PPM-X syndrome, but misregulation of genes in the brain likely plays a role.

Related Gene(s)

Changes in this gene are associated with PPM-X syndrome.

  • MECP2

How do people inherit PPM-X syndrome?

More than 99 percent of PPM-X syndrome cases occur in people with no history of the disorder in their family. Many of these cases result from new mutations in the MECP2 gene.

A few families with more than one affected family member have been described. These cases helped researchers determine that PPM-X syndrome has an X-linked pattern of inheritance. A condition is considered X-linked if the mutated gene that causes the disorder is located on the X chromosome, one of the two sex chromosomes. One copy of the altered gene in each cell is sufficient to cause the condition, although females with one altered copy of the gene are usually less severely affected than males.

Where can I find information about diagnosis or management of PPM-X syndrome?

These resources address the diagnosis or management of PPM-X syndrome and may include treatment providers.

  • Cincinnati Children's Hospital: MECP2-Related Disorders (
  • Gene Review: MECP2-Related Disorders (

You might also find information on the diagnosis or management of PPM-X syndrome in Educational resources and Patient support.

General information about the diagnosis ( and management ( of genetic conditions is available in the Handbook.

To locate a healthcare provider, see How can I find a genetics professional in my area? ( in the Handbook.

Where can I find additional information about PPM-X syndrome?

You may find the following resources about PPM-X syndrome helpful. These materials are written for the general public.

You may also be interested in these resources, which are designed for healthcare professionals and researchers.

What other names do people use for PPM-X syndrome?

  • PPMX

For more information about naming genetic conditions, see the Genetics Home Reference Condition Naming Guidelines ( and How are genetic conditions and genes named? ( in the Handbook.

What if I still have specific questions about PPM-X syndrome?

Ask the Genetic and Rare Diseases Information Center (

What glossary definitions help with understanding PPM-X syndrome?

bipolar disorder ; cell ; chromosome ; disability ; DNA ; gene ; inheritance ; mental retardation ; muscle tone ; parkinsonism ; pattern of inheritance ; prevalence ; protein ; psychosis ; psychotic ; sex chromosomes ; syndrome ; testes

You may find definitions for these and many other terms in the Genetics Home Reference Glossary.


  • Francke U. Mechanisms of disease: neurogenetics of MeCP2 deficiency. Nat Clin Pract Neurol. 2006 Apr;2(4):212-21. Review. (
  • Gonzales ML, LaSalle JM. The role of MeCP2 in brain development and neurodevelopmental disorders. Curr Psychiatry Rep. 2010 Apr;12(2):127-34. doi: 10.1007/s11920-010-0097-7. Review. (
  • Psoni S, Sofocleous C, Traeger-Synodinos J, Kitsiou-Tzeli S, Kanavakis E, Fryssira-Kanioura H. Phenotypic and genotypic variability in four males with MECP2 gene sequence aberrations including a novel deletion. Pediatr Res. 2010 May;67(5):551-6. doi: 10.1203/PDR.0b013e3181d4ecf7. (
  • Villard L. MECP2 mutations in males. J Med Genet. 2007 Jul;44(7):417-23. Epub 2007 Mar 9. Review. (


The resources on this site should not be used as a substitute for professional medical care or advice. Users seeking information about a personal genetic disease, syndrome, or condition should consult with a qualified healthcare professional. See How can I find a genetics professional in my area? ( in the Handbook.

Reviewed: October 2011
Published: November 23, 2015