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PubMed This is a summary of 27 peer-reviewed journal articles Updated
Immunology

Your Journey with Nijmegen Breakage Syndrome

At a Glance

Nijmegen Breakage Syndrome is caused by changes in both copies of the NBN gene, which helps repair DNA. It can lead to small head size, immune problems, growth and developmental differences, and increased cancer risk, making coordinated specialist care and regular surveillance important.

Hearing the words “Nijmegen Breakage Syndrome” (NBS) often marks the end of one difficult journey and the beginning of another. For many families, this diagnosis arrives after a long “diagnostic odyssey”—a period of searching for answers to unexplained symptoms like a small head size (microcephaly) or frequent infections [1][2].

It is completely normal to feel a wave of conflicting emotions. You may feel a sense of relief that the search for a name is over, but that relief is often quickly followed by shock, confusion, or a deep sense of worry about what this means for your child’s future [3][4]. You are not alone in these feelings; parents of children with rare genetic conditions often describe this moment as a major life pivot that requires both time and specialized support to process [5][6].

What is Nijmegen Breakage Syndrome?

Nijmegen Breakage Syndrome is an exceptionally rare genetic condition that affects how the body maintains its “instruction manual,” the DNA. In plain language, it is a DNA-repair disorder [7].

Every day, the DNA in our cells naturally suffers small breaks. Most people have a protein called nibrin (produced by the NBN gene) that acts like a specialized repair crew, rushing to fix these breaks before they cause problems [8][9]. In children with NBS, the nibrin protein is impaired or deficient because of changes (variants) in both copies of the NBN gene [10][11].

Without this repair crew, the DNA remains “unstable.” This instability is the underlying cause of the various health challenges seen in NBS, as the body’s cells cannot grow, develop, or protect themselves as they should [12][13].

Why Is It So Rare?

NBS is one of the rarest conditions in the world. It is most frequently found in people of Slavic descent (including those with heritage from Poland, Ukraine, Belarus, Russia, and the Czech Republic) [14][15].

This is because of a “founder effect”—a specific genetic change that occurred in a common ancestor hundreds of generations ago and has been passed down through these populations [14]. In some parts of Eastern Europe, the prevalence is estimated at about 2 to 3 per million people, though it can be higher in specific regions [15][16]. Outside of these populations, the condition is even more rare. However, NBS can occur in children of any ancestry, and ancestry alone should never determine whether a child receives testing or specialist care.

Hallmark Features of NBS

While every child is unique, NBS typically presents with a group of “hallmark” features that doctors use to recognize the condition [10]:

  • Microcephaly: A head size that is smaller than average, usually noticed at birth and becoming more prominent as the child grows [10][17].
  • Characteristic Facial Features: Many children share a characteristic facial appearance, which may include a prominent nose, receding forehead, and large eyes [17][18].
  • Immune System Challenges: A combined immunodeficiency, meaning the body has trouble making both the cells and the antibodies needed to fight off germs [19][20]. This often leads to frequent respiratory or sinus infections [10].
  • Growth and Development: Children frequently experience slower-than-average physical growth and varying degrees of developmental delay, learning differences, or intellectual disability [10][17].

Navigating the Uncertainty

One of the hardest parts of an NBS diagnosis is the uncertainty regarding the long-term “trajectory” or path of the disease. Because the DNA is unstable, children with NBS have a significantly higher risk of developing certain types of cancer, particularly lymphoma (a cancer of the immune system) [21][22].

Research shows that while the risk is high—with a large international registry study estimating a cumulative cancer incidence of about 40% by age 10 and nearly 78% by age 20—these are broad statistics [21][11]. It is important to remember that these figures reflect a specific historical cohort and cannot predict exactly what will happen for your specific child. What we do know is that early and consistent surveillance (regular check-ups and testing) is the best tool we have for managing this risk [19][23].

The Importance of Coordinated Care

Because NBS affects so many different parts of the body—the immune system, the brain, and the blood—it cannot be managed by a single doctor. Your child needs a coordinated care center or a multidisciplinary team [6]. This team usually includes:

  1. Immunologists to manage infection risks and immune health [19].
  2. Oncologists to create a personalized cancer screening plan [24].
  3. Geneticists to help your family understand the inheritance and provide counseling [23].
  4. Neurologists and Developmental Specialists to support your child’s growth and learning [25].

A critical rule for this entire team is the avoidance of nonessential ionizing radiation. Because your child’s cells cannot repair DNA damage effectively, standard X-rays, CT scans, and radiation therapy can be much more harmful to them than to other children [10][18]. However, you should never delay life-saving emergency imaging. Your specialized care team will help you navigate alternative imaging options, such as MRI or ultrasound, whenever possible.

Living with this diagnosis is a marathon, not a sprint. Focusing on building a team you trust and finding ways to connect with other NBS families can help turn the initial shock of diagnosis into a structured, proactive plan for your child’s care [26][27].

Common questions in this guide

How is Nijmegen Breakage Syndrome confirmed?
Genetic testing can confirm Nijmegen Breakage Syndrome by identifying disease-causing changes in both copies of the NBN gene. The genetics team can also explain whether the changes were inherited from each parent and what the results mean for the family.
What are the main signs of Nijmegen Breakage Syndrome?
NBS commonly includes microcephaly, or a smaller-than-average head size, characteristic facial features, frequent respiratory or sinus infections, and slower physical growth. Children may also have developmental delay, learning differences, or intellectual disability, but features and severity vary.
Does Nijmegen Breakage Syndrome increase a child’s cancer risk?
Yes. Children with NBS have a much higher risk of certain cancers, particularly lymphoma. A large historical registry estimated that the cumulative risk was about 40% by age 10 and nearly 78% by age 20, but those group estimates cannot predict an individual child’s outcome, so regular surveillance is important.
What kind of specialists should care for a child with NBS?
Care is usually coordinated through a multidisciplinary center with experience in NBS. The team may include an immunologist, oncologist, geneticist, neurologist, and developmental specialist, with each clinician addressing a different part of the child’s health.
Why should children with NBS avoid unnecessary X-rays and CT scans?
Impaired DNA repair can make nonessential ionizing radiation, including radiation from standard X-rays and CT scans, more harmful for a child with NBS. The care team may choose MRI or ultrasound when appropriate, but emergency imaging should not be delayed when it is needed to save a life.
Is Nijmegen Breakage Syndrome limited to children of Slavic ancestry?
No. NBS is reported more often in people with Slavic or Eastern European heritage because of a founder effect, but it can occur in children of any ancestry. Ancestry alone should never decide whether a child receives genetic testing or specialist care.
How are immune problems monitored in Nijmegen Breakage Syndrome?
An immunologist assesses the child’s immune status and monitors it over time, while the care team watches for recurrent infections. The exact follow-up plan is individualized and should be coordinated with the child’s specialists.

Questions to Ask Your Doctor

Curated prompts to bring to your next appointment.

  1. 1.Has genetic testing confirmed pathogenic variants in both copies of the NBN gene, and do you know if these variants were inherited from each of us?
  2. 2.Can you refer us to a multidisciplinary center that has specific experience managing Nijmegen Breakage Syndrome?
  3. 3.Which specialists will be on our child's core care team (e.g., immunology, oncology, genetics, neurology)?
  4. 4.What is our child's current immune status, and how will we monitor it over time?
  5. 5.How do we ensure that every doctor or radiology technician our child sees knows to avoid nonessential ionizing radiation?
  6. 6.What is the specific cancer screening and surveillance plan tailored for our child's age and diagnosis?
  7. 7.What local or national support organizations or parent networks can you recommend for NBS families?

Questions For You

Tap a prompt to share your answer — we'll use it plus this page's context to start a tailored conversation.

References

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This page provides general information about Nijmegen Breakage Syndrome for families and does not replace medical advice. Your child’s genetics, immunology, oncology, and other specialists should tailor testing, surveillance, imaging, and care to your child.

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