Simply Stated: Understanding the Walker-Warburg Syndrome, Muscle-Eye-Brain Disease, and Fukuyama Congenital Muscular Dystrophy Spectrum

Categorizing Walker-Warburg syndrome, muscle-eye-brain disease, and Fukuyama congenital muscular dystrophy

Congenital muscular dystrophies (CMD) are a group of inherited muscle disorders that become apparent within the first two years after birth. Within this category are the α-dystroglycanopathies, which result from abnormal glycosylation (sugar modification) of the α-dystroglycan protein. The most severe of these disorders are classified as muscular dystrophy-dystroglycanopathy type A (MDDGA) and have symptoms of congenital muscular dystrophy, with added brain and eye abnormalities.

The established forms of MDDGA include Walker-Warburg syndrome (WWS), muscle-eye-brain disease (MEB), and Fukuyama congenital muscular dystrophy (FCMD). These three conditions are often viewed as part of a spectrum, ranging from more severe to less severe forms. They are considered extremely rare and likely underdiagnosed. Though estimates vary among populations, MDDGA is thought to affect fewer than 1–2 per 100,000 live births worldwide.

Causes of Walker-Warburg syndrome, muscle-eye-brain disease, and Fukuyama congenital muscular dystrophy

In healthy individuals, the α-dystroglycan protein helps maintain muscle integrity and normal development of the brain and eyes before birth. Most cases of WWS, MEB, and FCMD are caused by disease-causing (pathogenic) variants in genes involved in the glycosylation of α-dystroglycan. When this process is disrupted, α-dystroglycan cannot function normally, leading to abnormal development of multiple organ systems. The disorders on the MDDGA spectrum are inherited in an autosomal recessive pattern, which means that two copies of the causative gene, one from each parent, are needed to develop the disorder.

It is important to note that variants in the same gene can lead to different forms of α-dystroglycanopathy. The resulting condition depends on the specific variant and how it affects α-dystroglycan glycosylation and function. WWS generally represents the more severe end of the MDDGA clinical spectrum, while MEB disease and FCMD typically have less severe presentations, although substantial overlap exists.

Pathogenic variants in about 16 genes have been associated with the α-dystroglycanopathies. However, a genetic cause is not identified in all affected individuals, and ongoing research continues to uncover additional disease-associated genes. The most commonly implicated genes in MDDGA include:

Walker-Warburg syndrome

• POMK
• DAG1
• POMGNT2
• B3GALNT2
• POMT1
• POMT2
• FKTN
• FKRP
• ISPD
• LARGE1
• B4GAT1
• TMEM5

Muscle-eye-brain disease

• POMGNT1
• POMT1
• POMT2
• FKTN
• FKRP
• GMPPB

Fukuyama congenital muscular dystrophy

• FKTN

Symptoms of Walker-Warburg syndrome, muscle-eye-brain disease, and Fukuyama congenital muscular dystrophy

The symptoms of WWS, MEB, and FCMD typically begin at or shortly after birth and involve the muscles, brain, and eyes. Although these conditions are generally considered severe, the severity and specific features vary by disorder and among affected individuals.

Walker-Warburg syndrome

Walker-Warburg syndrome (WWS) is the most severe of the MDDGA forms. Babies with WWS may have decreased movement before birth, severe muscle weakness, low muscle tone, and significant problems with brain development. Vision and eye problems are also common. The condition can cause serious breathing and heart problems early in life. Life expectancy is typically less than 3 years, with many children not surviving beyond the first year.

Muscle-eye-brain

Muscle-eye-brain disease (MEB) can cause muscle weakness, low muscle tone, developmental and learning difficulties, and vision problems. Changes in brain development may also occur. Some people with the condition are able to walk independently. Life expectancy varies depending on the severity of the condition.

Fukuyama congenital muscular dystrophy

Fukuyama congenital muscular dystrophy (FCMD) causes muscle weakness, low muscle tone, developmental and learning difficulties, and seizures. Changes in brain development are common, but eye problems are generally less severe than in MEB. Most people with FCMD do not develop the ability to walk independently, and breathing and heart problems can occur over time. Life expectancy is typically less than 20 years.

To learn more about the signs, symptoms, and causes of WWS, MEB, and FCMD, the following resources may be helpful:

• Lancet Neurology article by Walimbe, Muntoni, and Campbell (2026)
• Cure CMD: Resources, support, and information for individuals and families affected by congenital muscular dystrophy.

Diagnosis of Walker-Warburg syndrome, muscle-eye-brain disease, and Fukuyama congenital muscular dystrophy

Diagnosis in based primarily on clinical findings, brain and eye imaging, laboratory testing, and genetic testing. While muscle biopsy was historically used in diagnosis of the MDDGA types, it is no longer routinely required. Genetic testing is now the preferred approach for most patients. Evaluation may include:

• Neurological examination
• Brain MRI to identify characteristic abnormalities
• Comprehensive eye examination by a pediatric ophthalmologist
• Blood testing showing mildly to moderately elevated creatine kinase (CK) levels, a marker of muscle damage
• Genetic testing to identify the underlying disease-causing variant(s)

Notably, prenatal diagnosis may be possible for some cases of MDDGA. If the disease-causing gene variants have been identified in a family, chorionic villus sampling (CVS) or amniocentesis can be used to test for the known gene variants. Characteristic features may also be detected before birth using prenatal ultrasound and fetal MRI. Since such findings can occur in other conditions, however, genetic testing may be needed to confirm the diagnosis.

Current management of Walker-Warburg syndrome, muscle-eye-brain disease, and Fukuyama congenital muscular dystrophy

There is currently no cure or disease-modifying therapy for these conditions. Treatment focuses on supportive care and management of complications.

Care may include:

• Respiratory monitoring and support
• Nutritional support and feeding tube placement when needed
• Management of seizures and other neurological complications
• Physical and occupational therapy to help maintain mobility and prevent contractures, as appropriate
• Ophthalmologic care to monitor and manage vision problems
• Orthopedic management of joint contractures and other musculoskeletal complications
• Genetic counseling for affected families
• Palliative care and psychosocial support for affected children and their families

Since WWS, MEB, and FCMD affect multiple organ systems, care is typically coordinated by a multidisciplinary team that may include neurologists, pulmonologists, ophthalmologists, rehabilitation specialists, geneticists, neurosurgeons, gastroenterologists, nutrition specialists, and palliative care providers.

Evolving research and treatment landscape

The standard of care for WWS, MEB, and FCMD is still symptom management, but research advances offer hope for children living with these conditions. Researchers have identified many gene defects that cause forms of MDDGA. These discoveries have led to better understanding of disease mechanisms, as well as improved diagnosis.

Importantly, advances in gene replacement, gene editing, RNA-based therapies, and improved viral delivery technologies have transformed the treatment landscape for several neuromuscular diseases. Although these approaches are not yet available for WWS, MEB, and FCMD, researchers are exploring how similar strategies might one day be adapted for forms of α-dystroglycanopathy.

There are currently no clinical trials enrolling for MDDGA therapeutic candidates, however, several natural history studies aim to better understand the disease course of WWS, MEB, FCMD, and related congenital muscular dystrophies. Examples include:

• Congenital Muscle Disease Study of Patient and Family Reported Medical Information (CMDPROS) (Cure CMD), conducted with the Congenital Muscle Disease International Registry (CMDIR)
• Global FKRP Registry (Newcastle University)
• Clinical Trial Readiness for the Dystroglycanopathies (University of Iowa)

MDA’s work to further cutting-edge congenital muscular dystrophy research

Since its inception, MDA has invested more than $39 million in research on congenital muscular dystrophies, including the MDDGA forms WWS, MEB, and FCMD. Together with support from partner advocacy organizations and the National Institutes of Health (NIH), researchers have identified many of the genes responsible for these disorders, improving diagnosis and understanding of how they develop. While significant challenges remain, continued research is laying the foundation for future therapies and improving care for individuals and families affected by these rare conditions.

MDA’s Resource Center provides support, guidance, and resources for patients and families, including information about Walker-Warburg syndrome, muscle-eye-brain disease, and Fukuyama congenital muscular dystrophy, open clinical trials, and other services. Contact the MDA Resource Center at 1-833-ASK-MDA1 or ResourceCenter@mdausa.org.