Most Nijmegen breakage syndrome patients are of Slavonic origin , and all of them known so far carry a founder homozygous 5 nucleotide deletion in the NBS1 gene .
O B-DiseaseOrPhenotypicFeature I-DiseaseOrPhenotypicFeature I-DiseaseOrPhenotypicFeature B-OrganismTaxon O O O O O O O O O O O O O O O O B-SequenceVariant I-SequenceVariant I-SequenceVariant O O B-GeneOrGeneProduct O O