#392 Your DNA Is Not Static: Roxanne Khamsi on Mutation & Mosaicism

What if one of the biggest assumptions in genetics is also one of the most incomplete? We often talk about DNA as though it is a stable blueprint, a fixed set of instructions inherited at conception and carried unchanged throughout life.

But in Beyond Inheritance, science journalist Roxanne Khamsi challenges that idea in a profound way, arguing that our genomes are far more dynamic, unstable, and biologically creative than most of us realize.

In this episode, Roxanne Khamsi dives into the science and implications of mutations that arise after conception, the spontaneous, somatic, and mosaic genetic changes that shape our tissues, immune systems, brains, aging process, and risk for disease.

We talk about how these changes complicate the idea of inherited disease, how cancer can be understood through evolution, why some mutations are harmful while others may actually rescue disease, and what all of this means for the future of medicine.

In This Episode, We Discuss:

• Why DNA should not be viewed as static
• What somatic mutations are and why they matter
• The concept of mosaicism and what it means that every human is a mosaic
• How Darwinian evolution can happen within the body
• How mutation supports antibody diversity and immune defense
• Clonal hematopoiesis and its links to cardiovascular disease and aging
• Phenocopies and how spontaneous mutations can mimic inherited disease
• Cases where cells appear to self-correct through additional mutations
• Whether mutation accumulation may help drive aspects of aging

The Guest:

Roxanne Khamsi is an author, speaker, contributing writer for The Atlantic, and award-winning science journalist whose work has appeared in The New York Times, Nature, Scientific American, WIRED, and National Geographic. In Beyond Inheritance, she draws on more than two decades of reporting at the intersection of genetics and medicine to take readers through cancer biology, immune diversity, clonal hematopoiesis, somatic mosaicism, germline mutation, aging, and even microbial evolution, revealing mutation not as an occasional error, but as a constant force shaping life from within. Learn more on her website here.

Genetic Conditions Mentioned:

• Progeria
• Werner syndrome
• Hyper IgM syndromes
• Adenosine deaminase severe combined immune deficiency (ADA-SCID)
• VEXAS syndrome
• ​​Paroxysmal nocturnal hemoglobinuria (PNH)
• Duchenne muscular dystrophy (DMD)

Genetic History Timeline Referenced:

• 1881 - "Der Kampf der Theile im Organismus" (The Struggle of the Parts in the Organism) is published by Wilhelm Roux and read by Charles Darwin
• 1916 - Ernest Tyzzer  first used the term ‘somatic mutation’ with respect to a tumour
• 1953 - Rosalind Franklin's Photo 51 led to the discovery of the structure of DNA by James Watson and Francis Crick
• 1970s - The foundational X-inactivation studies in Paroxysmal Nocturnal Hemoglobinuria (PNH), notably the work by Oni, Osunkoya, and Luzzatto provided crucial evidence that PNH is a clonal disease arising from a somatic mutation in a hematopoietic stem cell
• 2003 - First draft of the human genome is announced complete.

Relevant Papers:

• Early somatic mosaicism is a rare cause of long-QT syndrome
• Variations have been identified in up to 20% of all cases of autism, with a single mutation in a single gene being largely responsible for driving critical neurodevelopmental differences.
• The role of somatic mutations in endometriosis: pathogenesis, progression, and fibrogenesis
• How Symptoms of Rare Diseases Can Mimic Common Conditions states rare disease patients average two to three misdiagnoses before their accurate diagnosis.
• Trisomy rescue

Science Fiction Recommendations - Genetics Edition

• Kira’s Favorite - Orphan Black
• Roxanne’s Favorite - Gattaca

Relevant DNA Today Podcast Episode:

#110 Gattaca, 22 Years Later

#134 Dr. Kat Arney on Cancer Evolution

#202 Duchenne Muscular Dystrophy (DMD) with Ann Martin and Madhuri Hegde

#250 Orphan Black: The Next Chapter with Madeline Ashby

#297 Ambry Genetics Exome Reanalysis with Dr. Elizabeth Chao and Kelly Hagman

#306 NIH’s Dr. Francis Collins on the Human Genome Project, and the Future of Genetics

#351 Mock Cardiac Genetic Counseling Session (Long QT Syndrome)

#365 Ending HIV, Accelerating COVID: Dr. Larry Corey’s Legacy in Vaccine Science

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