Ricciardone, M. D.Özçelik, T.Cevher, B.Özdaǧ, H.Tuncer, M.Gürgey, A.Uzunalimoǧlu, O.Çetinkaya, H.Tanyeli, A.Erken, E.Öztürk, M.2016-02-082016-02-0819990008-5472http://hdl.handle.net/11693/25283Heterozygous germ-line mutations in the DNA mismatch repair genes lead to hereditary nonpolyposis colorectal cancer. The disease susceptibility of individuals who constitutionally lack both wild-type alleles is unknown. We have identified three offspring in a hereditary nonpolyposis colorectal cancer family who developed hematological malignancy at a very early age, and at least two of them displayed signs of neurofibromatosis type 1 (NF1). DNA sequence analysis and allele-specific amplification in two siblings revealed a homozygous MLH1 mutation (C676T → Arg226Stop). Thus, a homozygous germ- line MLH1 mutation and consequent mismatch repair deficiency results in a mutator phenotype characterized by leukemia and/or lymphoma associated with neurofibromatosis type 1.EnglishAdultChildDisease associationDisease predispositionDNA repairDNA sequenceGene mutationGenetic analysisHematologic diseaseHumanNeurofibromatosisPhenotypePriority journalCarrier proteinsDNADNA repairFemaleGenetic predisposition to diseaseGerm-line mutationHematologic neoplasmsHumansMaleNeoplasm proteinsNeurofibromatosis 1Nuclear proteinsArticle