Introduction 

Bachmann-Bupp Syndrome (BABS) is a rare genetic condition, with only a limited number of cases reported worldwide. The syndrome affects both children and adults but usually has an early onset, often manifesting in childhood. BABS is caused by a change, known as a mutation, in a specific gene called ‘ODC1’ which stands for Ornithine Decarboxylase 1’. Due to the defective gene, the syndrome leads to developmental delays, hair loss (alopecia), and differences in overall facial bone structure. In addition to this, those with BABS often experience muscle weakness, abnormal bones and joints thus leading to altered movement. In this article, the skeletal and musculoskeletal abnormalities in BABS will be explored in depth, explaining the ways in which BABS changes the development of bones and muscles, why these changes occur, and what support there is for those living with the syndrome.¹ 

What is bachmann-bupp syndrome

Bachmann-Bupp Syndrome is a neurodevelopmental disorder that is caused by a mutation in the ODC1 gene. Genes play a major role in bone and muscle development, affecting how they form and function.¹ An example of an important gene in body development is a gene called ODC1. Normally, this gene controls the production of a protein that aids cell growth and development, which is vital for bone and muscle growth during early life. However, when there is a mutation in the ODC1 gene, there is a disruption in the production of molecules called polyamines, thus leading to the disruption of the normal development of skeletal and muscle tissues, explaining why those affected by Bachmann-Bupp Syndrome often have abnormal physical features.² 

If someone has one mutated copy of the ODC1 gene, they are still certain to develop Bachmann-Bupp Syndrome. This is known as a ‘full penetrance’ condition, meaning the gene mutation always leads to BABS.³ The majority of cases of BABS are caused by random mutations that aren’t inherited from parents.⁴ However, though it is rare, it is possible for BABS to be inherited. Therefore, genetic counseling is important for the management of the syndrome, where information is provided regarding the inheritance pattern of BABS, which discusses the possible risk of having affected children in future pregnancies, hence allowing families to plan correct decisions. 

Symptom overview of bachmann-bupp syndrome

BABS can present differently, varying between patients, but there are common features/symptoms that those with BABS share.⁵

• Alopecia 
  • Hair is usually present at birth, though sparse, but may be an unusual colour
  • Hair loss occurs in large clumps 
• Developmental delays
  • Walking, standing etc - due to muscle weakness 
• Hypotonia (low muscle tone) 
• Joint hyperflexibility: overly flexible joints, increasing risk of dislocation causing movement difficulties 
• Behavioural abnormalities - such as autism spectrum disorder, ADHD
• Feeding difficulties 

Understanding skeletal and musculoskeletal abnormalities in BABS

Genes, such as ODC1, influence bone and muscle development by instructing cells when to multiply and mature, but in BABS this process is disrupted. The abnormal gene results in an abnormally high level of the ODC protein,³ which causes impaired skeletal development resulting in differences in bone size, strength, and overall physical development.⁶ It has also been found that elevated ODC1 activity delays muscle cell differentiation, meaning they develop abnormally, resulting in decreased muscle tone and mass. 

Key skeletal and musculoskeletal features of BABS

Bachmann-Bupp Syndrome is characterised by several skeletal and musculoskeletal features.³ Those with BABS often have a larger head (macrocephaly), a higher forehead, wide-spaced eyes, a small flattened nose, and a small jaw (known as micrognathia). Those with BABS may also present with extra fingers (polydactyly) or fused fingers/toes (syndactyly). The syndrome results in low muscle town, contributing to delayed or impaired sitting, standing, and walking. Additionally, some individuals experience joint hypermobility and muscle weakness, contributing to difficulties in movement and coordination. Some with the syndrome also present with small and/or abnormally formed nails, large ears and a unique skull and facial bone formation.⁴ These features can impact day-to-day tasks, leading to challenges with mobility and overall physical development. 

How these abnormalities affect daily life

Daily life with BABS is quite challenging due to muscle weakness, joint hypermobility, and difficulties in basic physical tasks such as walking. Children with BABS often take longer to learn basic motor skills, affecting their independence and ability to partake in normal everyday activities. Those with the syndrome may require physical therapy and extra support. However, each individual's requirements and needs can be very different, meaning personalised care is essential.

Diagnosis

A proper diagnosis of Bachmann-Bupp Syndrome is crucial, as it allows those affected to receive the right care and treatments early on. For example, therapies such as physical or occupational therapy are used to address specific challenges. 

Diagnosing BABS begins with recognising the physical hallmark symptoms, such as developmental delays, hair loss (alopecia), and distinctive facial features. However, specialised genetic testing is required to provide a definite diagnosis. These types of tests look for the mutation in the ODC1 gene. Other tests may be performed for specific symptoms, for example, brain scans, known as an EEG (electroencephalography), to investigate specific changes in brain function, which has been demonstrated in several patients with BABS.³

Treatment and management of bachmann-bupp syndrome

BABS does not currently have a known cure, but there are several treatments and therapies to manage the symptoms and manifestations of BABS. The vast variety of symptoms necessitates a multidisciplinary treatment approach to alleviate discomfort aimed to improve an individual's quality of life.³ 

• Feeding difficulties: feeding therapy, gastronomy tube placement, stool softeners 
• Hearing loss: standard therapy is advised, which may include hearing aids etc
• Motor dysfunction & developmental delays: physical therapy is used to increase muscle strength and mobility 
• Behavioral concerns: neuropsychiatric evaluations³

Treatment of skeletal and musculoskeletal abnormalities 

The treatment approach for the skeletal and musculoskeletal abnormalities in BABS focuses on symptom management and functional improvement through physical therapy, use of adaptive aid equipment (such as wheelchairs), and supportive care. Orthopedic evaluations may be required to address bone deformities, such as scoliosis, with surgery considered in severe cases to improve mobility and/or to provide pain relief. Additionally, regular physical therapy can help maintain and improve motor functions, prevent complications, and allow the patient to gain more independence in day-to-day life. 

Advances in research and future directions

Though the discovery of BABS has been fairly recent, there have been several advances regarding the treatment of the syndrome. Scientists discovered that the syndrome is caused by a protein buildup in the body, due to the defective ODC1 gene, affecting how cells work and interact with one another. A medicine called DFMO, which has already been safely used for other conditions, has been found to reduce the symptoms in BABS. Researchers are now studying how to use this medicine to target the syndrome specifically, and looking for new, additional treatments to help even more. This growing knowledge and research offers hope for better care and quality of life for those with BABS in the future.^7,8,1

Key takeaways

Bachmann-Bupp Syndrome (BABS) is a rare genetic disorder, affecting development, muscle tone, and hair growth. The syndrome is caused by a mutation in a gene called ODC1, leading to an accumulation of a protein disrupting normal cellular functions, affecting how the body works. Key features include hair loss shortly after birth, delayed physical and developmental milestones such as walking and sitting, low/decreased muscle tone, and sometimes behavioural abnormalities. Although the number of those diagnosed is small, ongoing research and developments in treatment options, such as the drug DFMO, provide those with BABS hope for improving symptoms and their quality of life. Early diagnosis and a team tailored to the specific needs of each person is vital for supporting those affected and their families. 

Summary

Understanding the skeletal and musculoskeletal challenges in Bachmann-Bupp syndrome is imperative for providing effective care and support. While it is a complex and rare condition, advancements in medical research are providing new treatment options that can significantly improve the lives of those affected. Tailored therapies and interventions can help manage symptoms and enhance day-to-day life. With continued research and increased awareness, there is hope for better outcomes and greater support networks for people living with BABS.