Nijmegen breakage syndrome (pronounced NY-may-gen) is a rare genetic disorder. The syndrome is caused by a genetic mutation that affects your body’s ability to repair broken or damaged DNA inside your cells.

It’s estimated that fewer than 5,000 people in the United States have Nijmegen breakage syndrome (NBS).

People with NBS often experience growth deficiencies as newborns or in early childhood. Other complications include immunodeficiency, sensitivity to radiation, and an increased risk of cancer.

Let’s take a look at how NBS is diagnosed, managed, and whether anything can be done to prevent it.

One of the first symptoms of NBS is microcephaly, or having a smaller head circumference than other babies of the same age. Someone with NBS might fall behind on height milestones during the first 2 years of life with a normal growth rate afterward. The delay in growth frequently leads to an overall shorter height in adulthood.

Certain distinctive facial features can also lead doctors to suspect someone might have NBS. Some people with NBS might have:

  • a relatively larger nose or ears
  • a sloping forehead
  • a smaller jaw

Recurrent infections are common for people with NBS, especially respiratory infections. Recurrent infections might include:

Because NBS might first be identified at birth or during early childhood based on physical development and appearance, it may be useful to see pictures of people living with NBS to better understand the facial features doctors might be looking for.

NBS is an inherited disorder, which means that it passes from birth parents to children through genes.

It’s an autosomal recessive genetic disease, which means you must have two copies of the mutated gene to develop NBS. The only way to have two copies is to inherit one gene from each biological parent.

If you only have one copy of the mutated gene, your genes are called “heterozygous,” and you’re a carrier of the mutation but don’t have NBS. It’s possible to be a carrier of NBS without knowing it.

Children of two carriers of the NBS mutation each have a 25% chance of developing NBS, a 50% chance of being a carrier, and a 25% chance of not inheriting the mutated gene at all.

Because NBS is recessive, the genetic mutation can be present in a family for several generations without anyone knowing it. If a relative, such as a sibling or cousin, has NBS and you don’t, there’s a chance you’re a carrier. As a carrier you’re not at risk of developing NBS, but there’s a possibility that you could have children with NBS.

According to current research, NBS causes infertility in females, which makes it unlikely that they’ll pass on their genes. It’s not known whether NBS causes infertility in males. If someone with NBS does have children, they’ll inherit one copy of the mutated gene at a minimum.

People with Eastern European or Slavic ancestry are more likely to carry the genetic mutation that leads to NBS than other groups.

More than 99% of people with NBS have immunodeficiency. “Immunodeficiency” means that your immune system doesn’t function properly, leaving you at greater risk of infections. Respiratory infections are common, as are diarrhea and urinary tract infections.

Radiosensitivity is another potential complication of NBS, so people with NBS should avoid procedures such as X-rays and CT scans when possible and use MRI scans and ultrasounds instead.

The cognitive development of people living with NBS may be affected, and intellectual abilities may decline after early childhood.

Cancer is also a common complication of NBS, especially lymphoma.

People who are carriers of the NBS mutation may be at greater risk for some cancers, including breast cancer and prostate cancer. Additional screenings may be recommended by a doctor.

There’s no cure for NBS. Treatments are often limited to managing complications, such as infections or cancers, as they occur.

Antibiotics or other immunotherapies may be used to help offset the complications of immunodeficiency. Live vaccines should be avoided, including:

Cancer treatments may also need to be changed for people with NBS. Radiotherapy may need to be avoided, and chemotherapy may need to be more carefully monitored.

If your child, sibling, or another close relative is living with NBS, you may want to consult with a doctor about genetic testing to determine if you’re a carrier. Carriers have an increased risk of some cancers and may benefit from additional screenings.

If you have NBS, a doctor might recommend regular self-examinations for certain cancers. If you find something out of the ordinary, seek medical care.

Medical emergency

Recurring respiratory infections are common for people with NBS. If you have difficulty breathing, treat it as a medical emergency and call 911 or local emergency services.

A doctor might suspect someone has NBS at birth or during early childhood after considering microencephaly, facial features, growth milestones, and immunodeficiency.

If NBS is suspected, the most widely available way to confirm the diagnosis is with molecular genetic testing. The mutation that causes NBS is found on the NBN gene.

After a baby is born, nothing can be done to prevent NBS. For this type of genetic disorder, you either have it at the time you’re born or you don’t.

However, if you have NBS or suspect you or your partner might be a carrier, genetic counseling can help you determine the chance you have of passing one or two mutated NBN genes on to your future children.

The outlook for people with NBS is usually poor due to the high risk of severe infection and malignant cancer. According to a 2012 review of studies, more than 40% of people with NBS develop cancer by the age of 20. Catching cancer early is critical for treatment.

In one 2015 review of 149 people living with NBS, survival probabilities at varying ages were:

  • 95% at 5 years
  • 85% at 10 years
  • 50% at 20 years
  • 35% at 30 years

NBS is a recessive genetic disorder that must be inherited from both biological parents. Carriers of the genetic mutation might not know they have it. NBS is most common in Eastern European and Slavic populations.

There’s no cure for NBS, but its symptoms and complications can be treated. Frequently, it leads to respiratory infections and malignant cancers, and experts recommend regular screenings for some people with NBS.