Nijmegen Breakage syndrome (NBS) is a rare autosomal recessive disorder characterized by microcephaly, growth retardation, immunodeficiency, radiosensitivity, and cancer predisposition. Due to a founder mutation in the NBN gene, the disease is encountered most frequently among Slavic populations. Recently, a disease due to RAD50 deficiency has been reported. The patient displayed symptoms similar to NBS, microcephaly, mental retardation, bird-like face, and short stature. The MRE11/RAD50/NBN (MRN) complex plays a key role in recognizing and signaling DNA double-strand breaks.
