Opitz GBBB syndrome is a genetic condition caused by genetic changes (variants) in the MID1 gene on the X chromosome. This condition is often characterised by distinct facial features such as hypertelorism (widely spaced eyes), prominent forehead, widow’s peak (V-shaped hairline), broad nasal (nose) bridge and anteverted nares (upturned nostrils). Other features may include cleft lip and/palate, developmental delay, intellectual disability, as well as birth defects affecting the heart, anus and rectum (anorectal malformations), and midline brain (such as Dandy-walker malformation and agenesis of the corpus callosum). Symptoms can vary widely between individuals. Males are often more severely affected, whilst affected females tend to only have hypertelorism (widely spaced eyes).

Please note that some older resources may describe an autosomal dominant form of Opitz G BBB syndrome; however, that is now recognised as a separate condition.

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: Opitz BBB/G syndrome; Opitz BBBG syndrome; Opitz G/BBB syndrome; Opitz-G syndrome; X-linked Opitz syndrome (XLOS); X-linked Opitz G/BBB syndrome; MID1-related Opitz G/BBB syndrome

Please note that the following synonyms were previously used to describe this condition: Hypertelorism-hypospadias syndrome; Hypertelorism-oesophageal abnormality-hypospadias syndrome; Hypospadias-dysphagia syndrome; Opitz-Frias syndrome

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:2745 Opitz GBBB syndrome

ICD-11: LD2F.1Y Other specified syndromes with multiple structural anomalies, not of environmental origin

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.

Orphanet: Disability- ORPHA:2745 Opitz GBBB syndrome has information about the activity limitations that people with Opitz GBBB syndrome may face; please note that this was last updated in 2015 and may not reflect the most current information.

Opitz GBBB syndrome is a genetic condition. It is caused by disease-causing genetic changes (variants) in the MID1 gene on the X chromosome (X-linked condition).

Both males and females can be affected. As males only have one X chromosome, they have one copy of the MID1 gene, so if their MID1 gene has the disease-causing genetic variant, they will have Opitz GBBB syndrome. Females have two X chromosomes and two copies of the MID1 gene – if at least one of their copies has the disease-causing genetic variant, they may be affected, often with milder symptoms compared to males.

These genetic variants can 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 Opitz GBBB syndrome may include general practitioners (GP), paediatricians, geneticists, genetic counsellors, craniofacial surgeons, ophthalmologists, audiologists, 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.

The following guidance is available from international experts outside Australia; however, there may be information that is not relevant or applicable to the Australian context, and may not be up to date:

Orphananesthesia: Anaesthesia recommendations for patients suffering from Opitz G/BBB syndrome ; published in 2016.

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.

The following guidance is available from international experts outside Australia; however, there may be information that is not relevant or applicable to the Australian context, and may not be up to date:

Orphananesthesia: Anaesthesia recommendations for patients suffering from Opitz G/BBB syndrome ; published in 2016.

We are not aware of any rare disease organisations for Opitz GBBB syndrome in Australia. If you are aware of any Australian Opitz GBBB syndrome organisations, 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.

Opitz GBBB 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 Opitz GBBB syndrome can be found at:

• Genetic and Rare Diseases (GARD) Information Center: Opitz G/BBB syndrome
• National Organization for Rare Disorders (NORD): X-linked Opitz G/BBB Syndrome
• MedlinePlus Genetics: Opitz G/BBB syndrome

GeneReviews®: Opitz GBBB syndrome

Online Mendelian Inheritance in Man, OMIM®: #300000 Opitz GBBB syndrome

Orphanet: Opitz GBBB syndrome

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.