We obtained little or no effect on the equilibrium constant (KD: ∼ 300–500 nM) with the cerebellar ataxia-related XRCC1 K431N mutant and the cancer-associated variants P161L, R194W, R280H, R399Q, and Y576S (Fig. S5). The gene discussed is XRCC1; the disease is aceruloplasminemia.