wie viele gene hat ein mensch — can a DNA test help?

The human genome contains approximately 20,000–25,000 protein-coding genes, plus many non-coding regions. A DNA test can identify variants in these genes, but its ability to help with diet, fitness, or disease risk is limited. Most direct-to-consumer (DTC) tests analyze a few common SNPs with small effect sizes. They cannot prescribe a precise diet or predict complex diseases reliably. Polygenic risk scores for common conditions have low predictive power (AUC ~0.6) and are biased toward European populations. DNA tests can be useful for rare monogenic disorders, but for everyday health decisions, lifestyle factors and clinical biomarkers are far more important. Caveat: ISO certification covers lab quality, not clinical validity. The gene count is well-established, but the practical utility of DTC tests for complex traits remains weak.