Somatic PIGA mutations in HSPCs reveals longevity of adaptive NK cells. Normal HSPCs give rise to CD56^bright NK cells that further develop to canonical CD56^dim NK cells. Adaptive, CD56^dim NK cells derive from canonical CD56^dim NK-cell precursors in response to environmental stimuli. Patients with an acquired PIGA mutation exhibit mixed chimerism of GPI^pos and GPI^neg myeloid cells (represented here by neutrophils), reflecting the ongoing clonal contribution of PIGA mutated self-renewing HSPC. CD56^bright NK cells develop proportionally from GPI^pos and GPI^neg HSPC similar to myeloid cells. However, GPI^neg cells are underrepresented in the CD56^dim NK population, most prominently in CD56^dim NK cells with adaptive phenotype. The persistence of GPI^pos NK cells in PNH patients supports the notion of long-lived adaptive NK cells with self-renewal capacity similar to memory T cells.