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. 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
* Small head * Retarded growth * Immunodeficiency * Increased risk of cancer * Low birth weight
It is caused by a mutation in the NBS1 gene.
The diagnosis of Nijmegen breakage syndrome (NBS) is suspected in individuals with the following characteristic findings: * Microcephaly occurs in about 75% of affected individuals at birth, and in the remainder during the first months of life. * Growth retardation is either present at birth or becomes manifest before two years of age. Thereafter, growth rate is appropriate, but individuals remain small for age. * The characteristic facial features — a sloping forehead, receding mandible, prominent nasal root and nose, large ears, and upward slant of the palpebral fissures — become apparent at around three years of age. * Recurrent sinopulmonary infections include pneumonia, bronchitis, otitis media, sinusitis, and mastoiditis. * Malignancies, most commonly B-cell lymphoma, which develops in most individuals before the age of 15 years, occur in approximately 50% of individuals with NBS. * In most individuals, decline in intellectual ability results in mental retardation in the borderline-to-moderate range by age ten years.