657del5 mutation of the Nijmegen breakage syndrome gene (NBS1) in the Turkish population

The 657de15 mutation of the NBS1 gene has been demonstrated in most patients with Nijmegen breakage syndrome (NBS). We identified four Turkish families in which probands were diagnosed as having NBS and found to be homozygous for the 657de15 mutation. The 657de15 allele in the four Turkish families had a single origin.