Nijmegen Breakage Syndrome

Gene : NBN

What is Nijmegen Breakage Syndrome?

Nijmegen breakage syndrome (NBS) is a rare inherited disorder in which the body's DNA is unstable and tends to break. Most infants with NBS have unusually small heads at birth, or become more obvious or severe as the infant grows. Growth is usually slow during the first few years of life which leads to shorter than average height as the individual ages. Development and intellect appear to progress normally for the first few years of life but then begin to decline, causing mild to moderate intellectual disability. Individuals with NBS experience recurrent infections due to a malfunctioning immune system and are also at an increased risk of developing cancer. Most women with NBS will have premature ovarian failure and infertility issues. There is no cure for NBS; however medical surveillance and care may help to improve some symptoms and overall condition of life. Large doses of radiation are lethal for individuals with NBS so appropriate treatment for cancers must be discussed. NBS is caused by pathogenic variants in the NBN gene.

How is Nijmegen breakage syndrome inherited?

NBS is inherited in autosomal recessive manner. This type of inheritance requires the presence of two copies of a pathogenic variant in the gene for a person to have the genetic disease. Both parents must be carriers of a pathogenic variant in the gene in order to be at risk to have an affected child. The child must inherit a pathogenic variant from each carrier parent in order to be affected. There is a 1 in 4 chance that a baby will inherit two mutated copies of the gene and be affected when both parents are carriers.

What does it mean to be a carrier?

There are generally no signs or symptoms associated with being a carrier for NBS, although there is an elevated risk of cancer and monitoring for cancer is recommended. The risk of having a child affected with NBS is also increased. Testing of reproductive partners is recommended for carriers of NBS.

How common is Nijmegen breakage syndrome?

NBS is estimated to affect 1 in 100,000 newborns worldwide. It is more common among Polish, Czech and Ukrainian populations.

Family References and Resources
Clinician References
What is Analyzed?
  • Full gene sequencing
Affected Systems




Increased Cancer Risk

Carrier Rates
Detection Rate
Carrier Frequency
General Population > 99% 1 in 158

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