FoundMyFitness · 2020-12-22 · Rhonda Patrick (host), Steve Horvath

Dr. Steve Horvath on epigenetic aging to predict healthspan: the DNA PhenoAge and GrimAge clocks

45 claims checked against research: 1 contradicted 2 needing context 38 supported 4 unverified

2

Needs context

0:42:28Steve Horvathneeds contextmoderate

Genetic mutations that alter DNA methyltransferase activity in developmental disorders, such as Sotos syndrome, produce 5 to 10 year deviations in human epigenetic age.

"There are very exciting findings where people studied certain developmental disorders where where mutations deactivated DNA methyltransferase or mutation rendered it overactive, you know. And sure enough, all of these mutations in humans, you know, affect epigenetic age. And so at that level, we know it has an effect as expected, and the effect is pronounced. It could add fi It could add 5 or 10 years to a person, or or the opposite, you know." (said at 0:42:28)

The speaker accurately describes research showing that mutations in epigenetic machinery genes associated with developmental disorders markedly alter epigenetic age measured by DNA methylation clocks. In a landmark study examining patients with developmental disorders, loss-of-function mutations in NSD1 (which cause Sotos syndrome) were found to substantially accelerate epigenetic aging. However, NSD1 is technically a histone (H3K36) methyltransferase rather than a DNA methyltransferase, although H3K36 methylation directly directs and coordinates downstream DNA methylation patterns.

1:08:45Steve Horvathneeds contextmoderate

The human genome contains approximately 28 million cytosine locations, roughly a quarter of which change methylation status with age.

"And when you look at the genome, and we have in principle 28 million locations in the genome are cytosines, you know, and I want to say a quarter of them change with age." (said at 1:08:45)

The speaker's figure of approximately 28 million sites refers specifically to CpG dinucleotide methylation sites in the human genome, rather than all genomic cytosines (which total over 600 million base pairs across the ~3.1 billion base pair haploid genome). Published literature confirms that the human methylome consists of roughly 28 million CpG dinucleotides where DNA methylation typically occurs, and a substantial proportion of these sites undergo progressive alterations in methylation level across the lifespan (age-associated epigenetic drift and clock CpGs).

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