#392 - Genetic testing: when it's valuable, how to choose the right test, and what to do with the results

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In this episode, Peter explores the complex and often misunderstood world of genetic testing, building a practical framework for understanding what these tests can and cannot actually tell us about health and disease. He explains why some genetic findings can be genuinely life-changing while many others offer information that is far more probabilistic than deterministic, and why directly measuring the phenotype is often more valuable than inferring risk from DNA alone. Peter examines where genetics can provide meaningful insight across the major disease categories and where its predictive power is far more limited than many people assume. He also discusses how to think critically about different types of genetic tests, how to interpret results in the proper context, and how to avoid the common trap of accumulating more genetic information without gaining greater clarity or actionable insight.

We discuss:

• Genetic testing: understanding what it can reveal, where it falls short, and how to think about its clinical value [1:45];
• The Human Genome Project: why decoding DNA did not immediately unlock the mysteries of disease [4:15];
• The limitations of genetic testing: probabilistic risk, interpretive uncertainty, and the importance of phenotype [9:30];
• Questions to ask when considering genetic testing [15:45];
• Genetic testing in cardiovascular and metabolic disease: when genotype adds value beyond phenotype [17:00];
• Genetic testing for inherited cardiac conditions: identifying hidden risk beyond routine screening [21:45];
• Genetic testing for cancer risk: inherited syndromes, clinical utility, and the limits of consumer testing [24:00];
• Genetic testing for neurodegenerative disease: risk prediction, planning, and the challenge of limited actionability [28:45];
• Functional medicine genetic testing: the gap between biological plausibility and clinical evidence, and the supplement protocols that aren't supported by evidence [32:45];
• Pharmacogenetics: using genetic testing to guide medication selection and safety [38:45];
• A framework for evaluating genetic tests according to effect size and clinical actionability [41:45];
• The major types of genetic tests, and how each should be matched to the clinical question being asked [43:30];
• Interpreting genetic test results: choosing the right testing laboratory and understanding what the findings actually mean [49:45];
• Framework summary: why genetic testing is most valuable when it is guided by a clear question, matched with the appropriate test, and capable of meaningfully influencing decisions [56:45]; and
• More.

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