Although GluD2-R710W in the agonist binding domain segregated with disease in three siblings with cerebellar ataxia and delayed psychomotor development in a homozygous state [56] (Supplementary Table S3), it did not show constitutive currents when expressed in Xenopus oocytes (Table 3) or alter surface expression (Table 3). Here, GLUD2 is linked to aceruloplasminemia.