Nijmegen breakage syndrome

Nijmegen breakage syndrome (NBS), also known as Berlin breakage syndrome, ataxia telangiectasia variant 1 (AT-V1) and Seemanova syndrome, is a rare autosomal recessive congenital disorder causing chromosomal instability, probably as a result of a defect in the Double Holliday junction DNA repair mechanism and/or the Synthesis Dependent Strand Annealing mechanism for repairing double strand breaks in DNA (see Homologous recombination).