was sind gene — which blood markers matter?

Genes are segments of DNA that encode proteins, influencing many physiological processes, including blood marker levels such as LDL, HDL, triglycerides, CRP, and HbA1c. The provided context shows that genetic effects on these markers are often small (e.g., FTO on LDL, rs1205 on CRP). Clinically relevant blood markers include lipid profiles, inflammatory markers, and glycemic measures. While genetics contribute, lifestyle and environment usually dominate. Commercial DNA tests for these markers often lack robust clinical validation; evidence grades range from 'mechanistic' to 'marketing'. Therefore, blood markers should be interpreted by a healthcare professional, not solely from genetic tests. Caveat: The context does not provide a comprehensive definition of genes or an evidence-based list of important blood markers. The answer is conservative and general.