Fig 1: HLA class I and II alleles and KIR genotype. a HLA class I A, B and C with corresponding allotype designations (non-Bw4, Bw6, Bw4-80TA, C1 and C2), and HLA class II DPB1, DQB1 and DRB1 alleles are indicated as allele 1 and 2. HLA B*44:03:01 has a threonine (T) at position 80 as part of the Bw4 epitope (NLRTALR) of the a1 helix 2 of the molecule—and therefore will bind to KIR3DL1 on NK cells. HLA- Cw*07:01:01 (allotype C1) and Cw*04:01:01 (C2) have a lysine (K) and asparagine (N) at position 80, respectively—allowing for interaction with both KIR2DL3 (C1) and 2DL1 (C2) on NK cells. b The presence (coloured box) or absence of 16 KIR genes (14 functional and 2 pseudogenes 2DP1 and 3DP1) is shown. The child has an AA1 genotype, which has 9 KIR genes, has 2 copies of KIR3DL1 and 2 copies of activating gene KIR2DS4 with one full-length (f) and one truncated (v) version (heterozygous f/v). 2D: 2-domain; 3D: 3-domain; L: long tail, inhibitory; S: short tail, activating