In this report we describe the characterization of a novel null HLA‐DQB1 allele, detected by polymerase chain reaction‐sequence‐based typing but not by next‐generation sequencing (NGS). The new allele, HLA‐DQB1*06:379N, was discovered in an Italian patient with acute myeloid leukemia and also in one of her healthy siblings. The new allele is largely homologous to DQB1*06:02:01:01 with a T deletion in exon 2, in codon 11, which causes a frameshift and the formation of an unusual and premature TGA STOP in codon 27. This case report underlines the importance of not removing Sanger method sequencing from routine use for high‐resolution HLA typing, but to maintain it together with NGS technology.

HLA‐A*68:02:16 differs from A*68:02:01:01 by a single synonymous nucleotide change in codon 160 (CTG>CTA).

HLA‐C*06:297 differs from C*06:02:01:01 by a single nucleotide change in codon‐19 (CCC>TCC).

HLA‐DPA1*01:27 differs from DPA1*01:03:01:01 by a single non‐synonymous nucleotide change in codon 15 (ACG > ATG).

In recent years, the anti-leukemic potential of Natural Killer (NK) cells and their role in hematologic malignancies and in Hematopoietic Stem Cell Transplants (HSCT) has attracted greater interest and a recent study by Cooley S. et al. showed a better clinical outcome when patients with Acute Myeloid Leukemia received a transplant from unrelated Group B KIR haplotypes donors. As a consequence of these results, an algorithm called "KIR B-content score" was formulated. The aim of our research is a retrospective analysis of HSC unrelated transplants performed in our center to analyze the effect of the donor KIR B status on the clinical-outcome. Our results showed a better overall survival-rate in the AML recipients, HLA mismatched with the donor, when the donor KIR B content status is Best/Better (37% vs 18% at three years P=0,028). Moreover, we observed that AML recipients, whose Donors KIR B status was Best/Better, had more incidence of aGvHD grade I and II than patients whose Donors KIR B status was Neutral (70% vs 26%) and also a lower rate of relapse (36% vs 58%) and a better Disease Free Survival-rate (58% vs 38% at three years P=0,1) because of a better GvL effect.