NBN and ductal breast carcinoma in situ: We studied 564 Polish women with DCIS for eight Polish founder alleles, including four in CHEK2 (c.1100delC, c.444 + 1G > A, del5395 and c.470T > C), two in PALB2 (c.509_510delGA and c.172_175delTTGT), one in NBN (c.657_661delACAAA) and one in RECQL (c.1667_1667 + 3delAGTA).