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Cockayne syndrome type B
This condition affects growth, neurological development, and can lead to a shortened lifespan. It is caused by genetic changes in the ERCC6 gene, impacting how cells repair damaged DNA.
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Overview
Cockayne syndrome type B (CSB) is a rare genetic condition that primarily affects the nervous system and causes distinct physical features. Individuals with CSB often experience severe developmental delays, poor growth, and an increased sensitivity to ultraviolet (UV) light, known as photosensitivity [PMID:20301725]. The condition is one of several forms of Cockayne syndrome, all of which share some overlapping features but can differ in severity and specific genetic cause.
CSB is a serious disorder that typically presents in early childhood. It is characterised by progressive neurological degeneration and features of accelerated ageing. The condition affects individuals from birth, with symptoms becoming more apparent as they grow. The exact prevalence of CSB is not well established, but it is considered a very rare condition within the UK and globally.
Symptoms & clinical features
The symptoms of Cockayne syndrome type B are wide-ranging and affect multiple body systems. Infants with CSB may fail to thrive, showing difficulties with feeding and gaining weight. Developmental milestones, such as sitting, crawling, and walking, are often significantly delayed or not achieved [PMID:20301725]. Neurological problems are prominent and can include progressive intellectual disability, microcephaly (a smaller head size), and difficulties with movement coordination (ataxia).
Other common features include a distinctive facial appearance, which may include deeply set eyes and a thin nose. Extreme sensitivity to sunlight is a hallmark of CSB, leading to severe sunburns and skin damage even with minimal UV exposure. Vision and hearing impairments often develop over time, and some individuals may experience dental abnormalities, such as tooth decay or unusual tooth development. Short stature, joint contractures (stiffening of joints), and a shuffling gait are also frequently observed.
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Affected organs
Cockayne syndrome type B primarily affects the brain and nervous system, leading to widespread neurological dysfunction. The eyes and ears are also commonly affected, resulting in progressive vision and hearing loss. The skin is highly sensitive to UV radiation, leading to damage upon sun exposure. Bone growth and development can be impaired, contributing to short stature and joint issues. Additionally, the kidneys and liver can be affected in some individuals, though less commonly than neurological or sensory systems.
Risks & severity
Cockayne syndrome type B is typically a severe condition with a progressive course. The severity can vary between affected individuals, but most experience significant challenges related to their neurological development and systemic health. The life expectancy for individuals with CSB is often considerably reduced, with many not surviving beyond early adulthood. Progressive neurological decline, including issues with motor skills and mental function, is a key feature.
Complications such as frequent infections, malnutrition, and respiratory problems due to neurological impairment, contribute to the overall health risks. The photosensitivity means that exposure to sunlight must be carefully managed to prevent serious skin damage and further health complications. The progressive nature of the condition means that symptoms tend to worsen over time, requiring increasing levels of supportive care.
Genetic causes
Cockayne syndrome type B is caused by pathogenic variants in the ERCC6 gene. The ERCC6 gene provides instructions for making a protein called CSB (Cockayne Syndrome B) [PMID:20301725]. This protein plays a crucial role in a specific DNA repair pathway known as transcription-coupled nucleotide excision repair (TC-NER). This pathway is essential for fixing damage to DNA, especially in genes that are actively being used by the cell. When DNA is damaged, for instance by UV radiation, the CSB protein helps to recruit other proteins to the site of damage to facilitate its repair.
When there are pathogenic variants in the ERCC6 gene, the CSB protein either isn't produced correctly or doesn't function as it should. This leads to an accumulation of unrepaired DNA damage within cells, particularly in actively transcribed genes [PMID:33651478]. The inability to effectively repair this damage is thought to disrupt normal cellular processes, leading to cell death or dysfunction, which underlies the progressive neurological degeneration and other features seen in CSB. The accumulation of cellular damage is also often associated with accelerated ageing.
- ERCC6 ERCC excision repair 6, chromatin remodeling factorThe ERCC6 gene provides instructions for producing the Cockayne syndrome B (CSB) protein, crucial for DNA repair and accurate gene transcription.
Inheritance pattern
Cockayne syndrome type B is inherited in an autosomal recessive pattern. This means that a person must inherit two altered copies of the ERCC6 gene - one from each parent - to develop the condition. Individuals who inherit only one altered copy of the ERCC6 gene are called carriers. Carriers typically do not show any symptoms of Cockayne syndrome type B because their one working copy of the gene is sufficient for normal cellular function.
If both parents are carriers of a pathogenic ERCC6 variant, for each pregnancy, there is a 25% (1 in 4) chance that the child will inherit two altered copies and be affected by CSB. There is a 50% (1 in 2) chance that the child will be a carrier like their parents, and a 25% (1 in 4) chance that the child will inherit two working copies of the gene and not be affected and not be a carrier.
When both parents are carriers, each child has a 25% chance of being affected, 50% of being a carrier, and 25% of being unaffected.
Diagnosis & testing
The diagnosis of Cockayne syndrome type B is often suspected based on the characteristic clinical features, such as severe developmental delay, photosensitivity, and features of premature ageing. Physical examination and neurological assessment contribute to the clinical picture. Genetic testing is used to confirm the diagnosis by identifying pathogenic variants in the ERCC6 gene [PMID:20301725].
In the UK, genetic testing for Cockayne syndrome is available through the NHS Genomic Medicine Service (GMS) pathways. Referrals for genetic testing are typically made by a paediatrician, neurologist, or a clinical geneticist, often following an initial assessment. The relevant R-code for testing for Cockayne syndrome would typically fall under developmental disorders or neurological conditions with a genetic basis.
Management & lifestyle
While there is currently no cure for Cockayne syndrome type B, management focuses on alleviating symptoms, providing supportive care, and improving the quality of life for affected individuals. A multidisciplinary team approach is essential, often involving paediatricians, neurologists, geneticists, ophthalmologists, audiologists, physiotherapists, occupational therapists, and speech and language therapists.
Key aspects of management include rigorous sun protection to prevent photosensitivity-related skin damage, nutritional support to address growth challenges, and therapies to assist with developmental delays and physical limitations. Regular monitoring for vision and hearing changes, as well as kidney and liver function, is important. Genetic counsellors can provide valuable support and information to families regarding the inheritance pattern, prognosis, and options for family planning. The NHS provides comprehensive care pathways, with access to specialist services and genetic counselling through regional clinical genetics centres.
UK care pathway
In the UK, individuals suspected of having Cockayne syndrome type B would typically enter the NHS Genomic Medicine Service (GMS) pathway for diagnosis and management. Initial assessment by a specialist, such as a paediatrician or neurologist, often leads to a referral to a regional clinical genetics service. These services facilitate genetic testing, which is performed under specific NHS R-codes for rare developmental or neurological disorders. Genetic counsellors play a vital role, offering support, information, and help with understanding the genetic implications for the family.
Frequently asked questions
What is the typical life expectancy for someone with Cockayne syndrome type B?
Life expectancy for individuals with Cockayne syndrome type B is often significantly reduced. Many do not survive beyond adolescence or early adulthood due to the progressive nature of the neurological and systemic complications.
Can Cockayne syndrome type B be prevented?
Cockayne syndrome type B is a genetic condition caused by inherited gene variants and cannot be prevented. For families with a known history of the condition, genetic counselling can provide information about recurrence risks and family planning options.
Is sun exposure dangerous for someone with Cockayne syndrome type B?
Yes, individuals with Cockayne syndrome type B are extremely sensitive to sunlight (photosensitive). Even minimal UV exposure can cause severe sunburn and skin damage, making rigorous sun protection, including clothing and sunscreen, essential.
How is Cockayne syndrome type B inherited?
Cockayne syndrome type B follows an autosomal recessive inheritance pattern. This means a child must inherit two altered copies of the ERCC6 gene, one from each parent, to develop the condition. Parents who each carry one altered copy are typically unaffected themselves.
What kind of medical specialists are involved in managing Cockayne syndrome type B?
Management requires a team of specialists, including paediatricians, neurologists, geneticists, ophthalmologists, audiologists, physiotherapists, occupational therapists, and speech and language therapists to address the wide range of symptoms and provide comprehensive care.
References
- Sartorelli J, Travaglini L, Macchiaiolo M. Spectrum of ERCC6-Related Cockayne Syndrome (Type B): From Mild to Severe Forms. Genes. 2024. PMID: 38674442
- Kristensen U, Epanchintsev A, Rauschendorf MA. Regulatory interplay of Cockayne syndrome B ATPase and stress-response gene ATF3 following genotoxic stress. Proceedings of the National Academy of Sciences of the United States of America. 2013. PMID: 23733932
- Afonso-Reis R, Madeira CR, Brito DVC. Insights Into Cockayne Syndrome Type B: What Underlies Its Pathogenesis? Aging cell. 2025. PMID: 40536083
- Damaj-Fourcade R, Meyer N, Obringer C. Statistical Approach of the Role of the Conserved CSB-PiggyBac Transposase Fusion Protein (CSB-PGBD3) in Genotype-Phenotype Correlation in Cockayne Syndrome Type B. Frontiers in genetics. 2022. PMID: 35251122
- Hamam-Marawi G, Papadopoulou M, Ramachandran H. CRISPR/Cas9-mediated editing of ERCC6 in iPSCs: A disease model for Cockayne Syndrome type B. Stem cell research. 2026. PMID: 42349105
- Sonmez FM, Celep F, Ugur SA. Severe form of Cockayne syndrome with varying clinical presentation and no photosensitivity in a family. Journal of child neurology. 2006. PMID: 16900932