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Editor—Nijmegen breakage syndrome (NBS) is a rare autosomal recessive chromosomal instability disorder characterised by microcephaly, immunodeficiency, x ray hypersensitivity, and predisposition to malignancy. The gene responsible for NBS, NBS1, is located on chromosome 8q21 and encodes a protein called nibrin. This protein is a component of the hMre11/hRad50 protein complex, suggesting defective DNA double strand break (DSB) repair or cell cycle checkpoint function in NBS.1-7 In this report we describe a patient with the NBS phenotype, typical cytogenetic presentation with aberrations in chromosomes 7 and 14, and increased x ray sensitivity. Our index patient had deafness unlike all the other NBS patients reported so far. Mutation detection did not show a mutation inNBS1 and the protein nibrin was normally expressed.
Case report
The boy is the second child of non-consanguineous parents. His older sister is healthy. From the sixth month of pregnancy microcephaly and growth retardation were noted. Amniocentesis was performed followed by a cytogenetic study which showed a normal male karyotype. He was born in 1997 at 39 weeks of gestation. Birth weight was 1915 g, length 42 cm, and head circumference 28.5 cm (all below the 3rd centile). The neonatal period was complicated by mild hypoglycaemia. During the first year of life he suffered from …