NFKB1 and neuroblastoma: In this reference study, all very low birth weight PTNBs in the case group (100%) and 65% in the control group presented the variant NFKB1 allele (-94delATTG), unlike the present study, which, in the entire sample, consisted of 75 NB and in the molecular analysis of 150 alleles, the variant del allele was not determined.