Even in case no SELENOP-aAb were detectable in certain patients, the combination of the suggested biomarkers as indicators of (intracellular) selenoprotein deficiency may guide further analyses of alternative causes, such as interfering medication [35,55], Se uptake defects [56,57], (subclinical) chronic inflammation [58,59], malnutrition [[60], [61], [62]], or one of the rare genetic defects impairing selenoprotein expression [63,64]. The gene discussed is SELENOS; the disease is hyperinsulinemic hypoglycemia, familial, 4.