LCT and hyperinsulinemic hypoglycemia, familial, 4: They may be caused by pharmacologic mechanisms; e.g., caffeine has different pharmaco-kinetics depending on CYP1A2 genetic variant, similar to alcohol, depending on alcohol dehydrogenase (ADH) aldehyde dehydrogenase (ALDH) genetic variants, toxic reactions, e.g., high load of histamine in rotten fish or metabolic reactions, e.g., lactase deficiency.