was ist eine stoffwechselstörung — what does this mean exactly?

A metabolic disorder (Stoffwechselstörung) is a disruption of normal biochemical metabolism, often caused by genetic defects, enzyme deficiencies, hormonal imbalances, or environmental factors. In medicine, inborn errors of metabolism (e.g., phenylketonuria, maple syrup urine disease) are rare but well-characterized. Pharmacogenetics shows that variants in the TPMT gene cause thiopurine S-methyltransferase deficiency – a genuine metabolic disorder affecting drug processing (e.g., 6-mercaptopurine) and increasing toxicity risk. However, many consumer DNA tests market 'metabolic disorders' for weight loss or nutrition, despite the associated SNPs having tiny effect sizes and no RCT evidence supporting clinical utility. The evidence for such tests is weak (gwas/marketing). A true metabolic disorder requires clinical diagnosis, not a direct-to-consumer genetic result. Safety note: If a metabolic disorder is suspected, consult a physician before taking any action.