MECP2 duplication syndrome (also known as Proximal Xq28 duplication syndrome) is a chromosomal condition where there is a duplication of a region on the X chromosome. This region is called Xq28 and contains the MECP2 gene. Symptoms may include low muscle tone (hypotonia), developmental delay, intellectual disability, gastrointestinal issues, repeated respiratory infections that can be life-threatening, and seizures. MECP2 duplication syndrome is known as an X-linked condition and affects mostly males. Some females may be affected as well, but their symptoms tend to be more variable, ranging from mild to as severe as males.

Below on this page is some information about this condition as well as links to useful resources for Australians living with a rare disease.

Synonyms: Proximal Xq28 duplication syndrome; X-linked intellectual disability syndrome, Lubs type; syndromic X-linked intellectual disability Lubs type

Universal rare disease classifications provide a common language for recording, reporting and monitoring diseases. Please visit the Rare Disease Classifications page for more information about these internationally recognised classifications.

ORPHA:1762 Proximal Xq28 duplication syndrome

ICD-11: LD51 Structural anomalies of chromosome X, excluding Turner syndrome

Rare diseases typically display a high level of symptom complexity. There is often a wide range of symptoms and the symptoms may vary between individuals in terms of its presentation, severity, duration and impact.

Please speak to your medical team to learn more about the symptoms of this condition.

Rare diseases are often serious and progressive, exhibiting a high degree of symptom complexity, leading to significant disability. Majority of the estimated two million Australians living with a rare disease meet the Australian Government’s definition for disability (in accordance to the Australian Public Service Commission and Australian Bureau of Statistics), and many experience severe and permanent disability impacts. If you or someone you care for is experiencing disability-related impacts from a rare condition, please speak with a health or disability professional for advice. Information about relevant disability support can be found at the RARE Portal’s Disability Support Information page.

MECP2 duplication syndrome is a genetic chromosomal condition. It is caused by a duplication of a region on the X chromosome. This region is called Xq28 and contains the MECP2 gene. MECP2 duplication syndrome is known as a X-linked condition as it involves the X chromosome.

Both males and females can be affected. As males only have one X chromosome, they have one copy of the MECP2 gene, so if their MECP2 gene has the disease-causing genetic variant, they will have MECP2 duplication syndrome. Females have two X chromosomes and two copies of the MECP2 gene – if at least one of their copies has the disease-causing genetic variant, they may be affected, with symptoms in females varying from severely affected to mild or no symptoms (asymptomatic).

The duplication may be inherited (passed on to the next generation). More information on X-linked inheritance pattern can be found at Centre for Genetics Education: X-linked inheritance.

If you would like to learn more about the inheritance and impact of this condition, please ask your doctor for a referral to a genetic counsellor. Genetic counsellors are qualified allied health professionals who can provide information and support regarding genetic conditions and testing. More information about genetic counselling can be found at:

• Information on Genetic Services
• The National and State Services pages underneath the ‘Genetic Counselling’ sections listed

A timely diagnosis is critical for better patient outcomes, the provision of the best possible care and treatment options, access to services and support, increased reproductive confidence and the ability to participate in clinical trials.

Please speak to your medical team to learn more about the available diagnostic pathways for this condition.

Please speak to your medical team to learn more about the possible treatment or management options for your condition. Treatment will depend on an individual’s specific condition and symptoms. It is also important to stay connected to your medical team so that you can be made aware of any upcoming clinical trial opportunities. For many rare diseases, treatment options may be limited. Participation in a clinical trial may provide access to new or emerging therapies.

Healthcare professionals involved in the care of individuals with MECP2 duplication syndrome may include general practitioners (GP), paediatricians, gastroenterologists, neurologists, immunologists, physiotherapists, occupational therapists, speech therapists and others. The need for different healthcare professionals may change over a person’s lifetime and extend beyond those listed here.

Clinical care for rare diseases often involves a multidisciplinary team of medical, care and support professionals. Please note that the information provided here is as a guide and that RVA does not necessarily monitor or endorse specific clinics or health experts.

This may not be applicable to all rare diseases but for many, palliative care services may be relevant and useful. Palliative care services are available for people (adults, children and their families) living with a life-limiting illness and is not only for end-of-life care. It can also help at any stage of illness from diagnosis onwards, and will look different for different people. Palliative care services provide assistance, support, resources and tools to help people manage their illness and the symptoms, ease pain, and improve comfort and quality of life. If this is relevant to you and you wish to find out more information about palliative care and how it can help you, please visit:

• Australian Institute of Health and Welfare: Palliative care Overview
• Australian Government Department of Health, Disability and Ageing: Palliative care
• Palliative Care Australia

If you know of any relevant care guidelines, please let us know via the Contribute page.

Individuals living with rare diseases may have complex medical issues and disabilities, which are not always visible. It is often useful to refer to their medical history as well as personal information such as a medical card, doctor’s letter, or if available, a rare disease passport, for relevant information.

In addition, individuals, their parents, families and carers often develop extensive expertise on their specific rare disease. It is important to recognise that they can contribute valuable knowledge about their rare condition. Rare diseases often impact individuals differently, so it’s important to consider a person’s lived experience.

If you know of any relevant emergency management guidelines or information relevant to emergency care, please let us know via the Contribute page.

MECP2 duplication syndrome (MDBase) is an international database that was established to better understand the natural history of MECP2 duplication syndrome (MDS). It collects information directly from families and caregivers about the health, development, and wellbeing of individuals with MDS.

We are not aware of any rare disease organisations for MECP2 duplication syndrome in Australia or internationally. If you know of any rare disease organisation, please let us know via the Contribute page.

Genetics Alliance Australia (GAA) may be able to provide some support for families and individuals affected by an undiagnosed or rare genetic condition for which there is no disease specific organisation in Australia.

Please note that RVA does not monitor or endorse each group/organisation’s operational governance and activities. When engaging with a group, please consider the information on the RARE Portal’s Finding Helpful Peer and Community Supports page.

MECP2 duplication syndrome varies between individuals, and each person’s experience is unique.

If you would like to share your personal story with RVA, please visit the Rare Voices Australia: Share Your Story page. RVA will consider your story for publishing on our website and inclusion on the RARE Portal.

For information on available government and social services that provide support for individuals with a rare disease, please visit the National and State Services pages.

People living with a rare disease often face unique challenges such as diagnostic delays, misdiagnoses, limited treatment options, and limited access to rare disease specialists and support. These challenges may impact people’s emotional wellbeing and quality of life. Many find it helpful to seek mental health and wellbeing support to cope with ongoing stress and uncertainty. Connecting with people who have shared experiences through a support group may also be helpful. Information about relevant mental health and wellbeing support can be found at:

• Mental Health and Wellbeing Support for Australians Living with a Rare Disease
• The National and State Services pages underneath the ‘Mental Health’ sections listed

Further information on MECP2 duplication syndrome can be found at:

• Genetic and Rare Diseases (GARD) Information Center: Proximal Xq28 duplication syndrome
• National Organization for Rare Disorders (NORD): Proximal Xq28 duplication syndrome
• MedlinePlus Genetics: MECP2 duplication syndrome

GeneReviews®: Proximal Xq28 duplication syndrome
Online Mendelian Inheritance in Man, OMIM®: #300260 Intellectual developmental disorder, X-linked syndromic, Lubs type
Orphanet: Proximal Xq28 duplication syndrome
Human Disease Genes (KU Leuven): MECP2 duplication – information for professionals

This page has been developed by Rare Voices Australia (RVA)’s RARE Portal team.

If you are aware of any additional information that may benefit stakeholders with an interest in this page, or if you notice any broken links or inaccurate information, please let us know via the Contribute page.