Nijmegen breakage syndrome
A rare autosomal recessive disorder (OMIM:251260) characterised by chromosomal instability, radiation sensitivity, microcephaly, growth retardation, immunodeficiency and predisposition to cancer, particularly to lymphoid malignancies.
Molecular pathology Defects in NBN, which encodes a protein that belongs to the MRN complex that plays a critical role in the cell response to DNA damage, cause Nijmegen breakage syndrome.
Nijmegen is the Dutch city where the condition was first described; most patients however are western Slavic and live in Poland.
Synonyms Ataxia-telangiectasis variant V1, Berlin breakage syndrome, non-syndrome microcephaly—autosomal recessive—with normal intelligence, Seemanova syndrome