Nijmegen breakage syndrome

Nijmegen breakage syndrome (NBS) (also known as Berlin breakage syndrome and Seemanova syndrome) is a rare syndrome characterised by chromosomal instability, probably as a result of a defect in the Double Holliday junction DNA repair mechanism.

It is characterized by microcephaly, a distinct facial appearance, short stature, immunodeficiency, radiation sensitivity and a strong predisposition to lymphoid malignancy.

It is caused by a mutation in the NBS1 gene.

The name derives from the Dutch city Nijmegen where the condition was first described.

Most people with NBS have West Slavic origins. The largest number of them live in Poland.