Effect of naturally occurring mutations in MYH9 on human NK-cell cytotoxicity. (A) Schematic depicting the major functional regions of a myosin IIA molecule, indicating the position of MYH9 mutations in patients whose NK cells were used in this study. (B) Cytotoxic activity of negatively selected, purified ex vivo human NK cells from patients with mutations in the head (S96L, patient 1 [P1]), S2 (T1155I, P2), rod (R1400W, P3; D1424N, P4-P6), and tail (5779delC, P7) domains of MYH9 was compared with control donors in ⁵¹Cr-release assays against K562 target cells. Results from 1933x patients were published previously¹⁵  and are shown for comparison. Results are listed as lytic units required for 10% lysis of target cells (LU₁₀). Results are adjusted for NK-cell purity of the isolated cells, and patient cell LU₁₀ is normalized to control for each assay. For 1933x, when > 1 patient was analyzed, the mean ± SD is shown.