657del5 mutation in the gene for Nijmegen breakage syndrome (NBS1) in a cohort of Russian children with lymphoid tissue malignancies and controls.

Nijmegen breakage syndrome (NBS, OMIM 251260) is a rare hereditary disease, characterized by immune deficiency, microcephaly, and an extremely high incidence of lymphoid tissue malignancies. The gene mutated in NBS, NBS1, was recently cloned from its location on chromosome 8q21. The encoded protein, nibrin (p95), together with hMre11 and hRad50, is involved in the double-strand DNA break repair system.

Nijmegen breakage syndrome: clinical characteristics and mutation analysis in eight unrelated Russian families.

Objective: The purpose of the study was to ascertain patients with Nijmegen breakage syndrome (NBS) in the Russian population and characterize the clinical phenotype and molecular genotype of these patients.

Study Design: Eight unrelated Russian patients with possible diagnoses of NBS were identified. Family histories were collected and clinical and laboratory analyses were carried out.