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Bohring-Opitz Syndrome (ASXL1)

Bohring-Opitz Syndrome (ASXL1) is a rare neurodevelopmental disorder caused by a genetic change in the ASXL1 gene. It often involves severe developmental delays, distinct facial features, and medical complications. While the condition is ultra-rare, with only a small number of diagnosed cases globally, each individual’s experience can vary. Research into Bohring-Opitz Syndrome is still emerging, and every data point matters as we work toward better understanding, treatments, and future clinical trials.

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What is Bohring-Opitz Syndrome (ASXL1)?

Overview

Bohring-Opitz Syndrome is a very rare neurodevelopmental disorder that is typically caused by a de novo (new) change in the ASXL1 gene. In some rare cases, the variant may be inherited from parents.

Bohring-Opitz Syndrome, which is sometimes abbreviated as BOS or BOPS, is named after Axel Bohring and John Opitz, two of the doctors to initially describe early cases of Bohring-Opitz Syndrome between 1999 and 2006. Bohring-Opitz Syndrome was originally diagnosed based on a set of observable clinical features (Hastings 2011). Variants in a specific gene – ASXL1 – were discovered to be the cause of these features in 2011.

How the ARRE Foundation is helping

Our understanding of Bohring-Opitz Syndrome and the ASXL1 gene has improved rapidly in the last several years, driven in large part by the ARRE Foundation’s efforts to fund and engage families in research studies. However, there are still many unanswered questions about Bohring-Opitz Syndrome and how to treat it. The ARRE Foundation’s goal remains to engage our global community of advocates to support research to discover treatments and improve the standard of care for Bohring-Opitz Syndrome.

Diagnosis of Bohring-Opitz Syndrome and other ASXL1 variants

Gene sequencing, a type of broad genetic testing, is typically used to identify a change or variant in the ASXL1 gene. Bohring-Opitz Syndrome is a specific diagnosis usually linked to a particular type of genetic variant in the ASXL1 gene that causes a set of recognizable clinical features. The specific genetic variants currently associated with Bohring-Opitz Syndrome are typically (but not always):

De novo, meaning they are a new variant or mutation and is not inherited from a parent
Pathogenic or likely pathogenic, meaning they are known or suspected to cause disease based on evidence analyzed by the testing laboratory
Truncating variants, like a nonsense or frameshift mutation, that results in the production of a shortened protein than is produced by a typical gene
Occur in the last two sections (exons) of the ASXL1 gene

Other types of variants in the ASXL1 gene, such as inherited or missense variants, may not lead to a Bohring-Opitz Syndrome diagnosis. We’re still learning how these other variants affect people and how their symptoms may differ. See below for information about uncertain diagnoses, including a variant of uncertain significance (VUS).

Unless otherwise noted, the information on this page focuses on Bohring-Opitz Syndrome, since most research so far has involved people with this specific diagnosis. However, if your loved one has a different ASXL1 variant, you may still find this information and the community resources helpful. The ARRE Foundation is here to support everyone affected by changes in any of the ASXL genes, as we continue to learn more about these rare and complex conditions.

Uncertain diagnoses: If your loved one has a variant of uncertain significance (VUS) or otherwise does not have a definitive Bohring-Opitz Syndrome diagnosis, please reference our Uncertain Genetic Diagnosis resources for more information.

Uncertain Genetic Diagnosis

Prevalence of Bohring-Opitz Syndrome

We don’t know how many people have an accurate diagnosis. We estimate that there are approximately 300 people diagnosed with Bohring-Opitz Syndrome in the world. We also believe there are many people living undiagnosed who have not had genetic testing.

Get your loved one counted! Help us develop a more accurate estimate of the number of people who have Bohring-Opitz Syndrome and other ASXL variants by completing the ASXL Census.

Join the ASXL Census

Symptoms and features of Bohring-Opitz Syndrome

There is significant variability in the symptoms and clinical features in Bohring-Opitz Syndrome, including a wide spectrum of severity. We don’t yet know why changes in the ASXL1 gene cause this wide spectrum of symptoms and features (known as genotype-phenotype correlation).

Some of the most common characteristics of Bohring-Opitz Syndrome include:

Distinct features of the face and head, including a heart-shaped birthmark on the forehead (glabellar nevus flammeus), prominent eyes, high arched palate, and head shape anomalies (microcephaly and/or trigonocephaly)
“BOS posture” where the wrists are turned inward
Feeding difficulties (particularly in infancy), including reflux and cyclic vomiting that may be extreme and lead to hospitalization (see “Important notes” below)
Recurrent infections, including respiratory infections and urinary tract infections (see “Important notes” below)
Constipation and motility issues
Respiratory infections, particularly in infancy
Seizures
Sleep disturbances, including irregular sleep/wake cycles
Obstructive and/or central sleep apnea
Orthopedic concerns, including hip dysplasia, scoliosis, and kyphosis
Brain abnormalities on MRI, including corpus collosum abnormalities
Gross motor delay of varying severity
Intellectual disability of varying severity
Issues with vision and the eyes, including myopia and issues with the retina and optic nerve
Increased risk for developing Wilms tumor, a rare pediatric kidney cancer, and hepatoblastoma, a rare pediatric liver cancer (see tumor screening guidelines below)

This list includes features documented in the medical literature noted below and symptoms observed in the ASXL1 family community.

View symptom chart

Overview

There are currently no specific treatments to address the underlying cause of Bohring-Opitz Syndrome. The treatment approach for Bohring-Opitz Syndrome typically includes the management of complications through a multidisciplinary team of medical specialists and therapists. Interventions may include intensive therapies, surgeries, and medication (such as seizure medications) as needed.

Evaluation and management of symptoms

Individuals with Bohring-Opitz Syndrome are typically evaluated and followed by multiple medical specialists. These documents may be helpful references in guiding care, including which medical specialists are recommended to evaluate specific symptoms or concerns:
• Living with Bohring-Opitz Syndrome guide (2024)
• Bohring-Opitz Syndrome GeneReviews chapter (Russell 2026)
• ASXL-related disorders: Educational guide for healthcare professionals (2024)

Coordination of care

Coordinating medical care across many specialties can be extremely challenging. Finding a champion in your clinical team can help. A general pediatrician, developmental pediatrician, clinical geneticist, or neurologist might be well-suited to this role. ASXL families have also shared that engaging a complex care team or palliative care team, whose role is to see the patient wholistically, may be helpful in coordinating care.

Supporting development

Individuals with Bohring-Opitz Syndrome benefit significantly from different types of therapy to help build skills and prevent developmental regression. Slow or minimal developmental gains are typical. Trained therapists in these specialties may also help you identify and secure specialized adaptive equipment and tools to use at home, at school, and in the community.

Common types of therapy include:
• Physical therapy
• Occupational therapy
• Speech therapy to aid in communication skills
• Feeding therapy to aid in feeding and swallowing skills

ASXL families have also shared benefits of other types of therapies, including equine therapy (horse therapy), water therapy, music therapy, and therapy intensives (frequent therapy sessions over a short period of time).

Important notes for doctors and caregivers

While there are many complications and challenges in Bohring-Opitz Syndrome, some can be very serious and require close monitoring and management particularly in infants and very young children.

Tumor screening

There are approximately 10 known cases of rare pediatric cancers of the kidney (Wilms tumor) and liver (hepatoblastoma) in individuals with Bohring-Opitz Syndrome. An abdominal ultrasound every three months from birth to age 8 is recommended to screen for the development of tumors on the kidneys and liver. Discuss with your child’s provider the option of measuring alpha fetoprotein (AFP) via blood test every 3 months through age 5 and/or extending ultrasound screenings after age 8 at a lower frequency. Read the full updated tumor screening guidelines (May 2024).

If your loved one or patient with Bohring-Opitz Syndrome has been diagnosed with cancer, we encourage you to reach out to us (info@arrefoundation.org) to report your experience as this information helps support screening recommendations.

Aspiration

Aspiration, or the inhalation of food or vomit into the lungs, can happen without obvious outward signs (“silent aspiration”). Aspiration poses a risk of respiratory infection, which can be very serious for individuals with Bohring-Opitz Syndrome. A feeding or swallow study can help identify aspiration risk.

Cyclic vomiting

Cyclic or chronic vomiting can be extremely challenging to manage especially as it may lead to repeat hospitalization due to dehydration, failure to thrive, or infection due to aspiration. Triggers for feeding-related issues may include vaccinations, infections, and anesthesia, although it is recommended that all individuals with Bohring-Opitz Syndrome receive full courses of standard vaccinations. Doctors can also prescribe medications that prevent vomiting, such as antiemetics. These can be combined with a pain reliever and/or sedative to help end bouts of vomiting. Cyproheptadine has been noted as a daily treatment to prevent cyclic vomiting (Russell 2018). Feeding issues, reflux, and vomiting do typically improve with age.

Risk of infection

There is an increased risk of infection of all types in Bohring-Opitz Syndrome, including ear infections, urinary tract infections, and respiratory infections. Respiratory infections (even the common cold) can be very serious for individuals with Bohring-Opitz Syndrome. Respiratory symptoms should be monitored closely.

Life expectancy for Bohring-Opitz Syndrome

As genetic testing becomes more widely accessible, we are learning of more people who have been living undiagnosed with Bohring-Opitz Syndrome for many years. The oldest known individual with Bohring-Opitz Syndrome was in their 40s.

All of the people we are aware of who have Bohring-Opitz Syndrome cannot live independently and require lifelong care. Some symptoms seem to change over time, including some symptoms that improve (such as feeding difficulties) and some symptoms that worsen (such as orthopedic challenges). Bohring-Opitz Syndrome is not known to be a neurologically degenerative disorder where cognitive function and ability decreases over time.

Not enough research has been conducted to know what the average Bohring-Opitz Syndrome life expectancy could be. You can help us learn what life with Bohring-Opitz Syndrome looks like over time by enrolling your loved one in the ASXL-Related Disorders Natural History Study.

Enroll your loved one

Clinical research papers about Bohring-Opitz Syndrome

The following research papers include comprehensive descriptions of the clinical features of Bohring-Opitz Syndrome:

GeneReviews: Bohring-Opitz Syndrome (Russell 2026)
- Includes recommendations for care management and evaluation (updates to this publication are in progress and are anticipated in 2026)
Clinical findings in 39 individuals with Bohring–Opitz syndrome from a global patient-driven registry with implications for tumor surveillance and recurrence risk (Russell 2023)
- Summarizes known clinical features including hospitalizations and surgeries
Clinical management of patients with ASXL1 mutations and Bohring-Opitz syndrome, emphasizing the need for Wilms tumor surveillance (Russell 2015)
- Summarizes eight individuals with Bohring-Opitz Syndrome in significant detail

View more published research

Community and support for Bohring-Opitz Syndrome families

ARRE Foundation connections and resources

Connect with us:

Email: Sign up for our email list, which includes our monthly newsletter, announcements, and research opportunities
Social media: Follow us on Instagram, Facebook, and LinkedIn

Find our best resources for families:

Virtual events and conferences

The ARRE Foundation hosts regular virtual events to support ASXL parents and caregivers, including welcome calls for newly diagnosed families, educational webinars, and other support topics.

The ASXL Family Conference, an in-person opportunity to meet other ASXL families and participate in research, is held every other year. The next ASXL Family Conference will be in 2026.

Parent support group (Facebook)

The Bohring-Opitz Syndrome support group on Facebook was founded in 2011 by Sünne van Gemert-Godbersen and Sheri Bermejo, both parents of children with Bohring-Opitz Syndrome. This grassroots group has grown from just a handful of members in its early days to hundreds of members from around the world. (This group is not administered or managed by the ARRE Foundation.)

Bohring-Opitz Syndrome Awareness Day

Bohring-Opitz Syndrome Awareness Day is April 6. Stand with families around the world to honor our loved ones living with Bohring-Opitz Syndrome, raise awareness, and drive critical ASXL-related research forward.

Check out our Bohring-Opitz Syndrome Awareness Day resources.

Other organizations and resources

bohring-opitz.org: This is an informational website run by families with research, family stories and a map of families with Bohring-Opitz Syndrome.

Bohring-Opitz Syndrome Foundation: The BOS Foundation provides family support, raises awareness of Bohring-Opitz Syndrome, and offers financial scholarships for families to help pay for things such as adaptive equipment.

“Kuluut” documentary: The documentary “Kuluut” follows Coen, who has Bohring-Opitz Syndrome, and his family. The trailer is available online and the full documentary is available on The Disorder Channel (accessible via Roku or Amazon FireTV).

Family stories: Some families have social media pages and blogs about their experience with Bohring-Opitz Syndrome. Those include: