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Promises and Limitations of the “Personalized Care” Movement: Where We Are Now

Several years ago, I gave my take on the “personalized care” movement [1]: the broad push to use a person’s genetic data to design optimal therapies, treatments, interventions, and pharmaceuticals. I was supportive and hesitantly optimistic, but I also acknowledged the limitations and drawbacks. Yes, genetics do determine how we respond to different therapies, and we can optimize medical care using the information—if we understand what our genes are saying and how they interact with the environment.

It’s only picked up steam. In last year’s State of the Union address, President Obama announced the Precision Medicine Initiative [2], pledging renewed efforts and funding to develop treatments tailored for an individual’s genetics, lifestyle, and environment. Businesses have sprung up promising to analyze your genetic data and create personalized workout routines, meal plans, and daily habits.

We’ve made big strides in personalized medicine [3].

We’re often able to fine-tune dosages of pharmaceuticals to avoid overdosing people with genetic sensitivities and under-dosing people with genetic resistance. It’s not exactly easy or fast, but it’s possible.

Researchers have identified genetic variants that increase statin-induced muscle damage [4]. Doctors are choosing antidepressants based on a patient’s genetics (“pharmacogenomics”) and seeing [5] a 53% improvement in reduction of depressive symptoms; they’re also using genetics to predict non-responding patients [6].

Since 2005, we’ve used genome-wide association studies (GWAS) to identify over 2000 “robust” associations [7] between genetic variants and medical conditions and traits, many of which are predictive and medically useful.

Genetics determines how we react to different foods, nutrients, and exercising and feeding strategies. It can affect how much of each nutrient we need and how likely we are to become obese [8]We know a fair amount about how recent ancestry impacts optimal diet [9], including folate requirements, carb tolerance, and dairy sensitivity. 

And because we contain far more microbial DNA than human DNA, analyzing the genomes of our gut biome could give us great insight into our immune [10], mental [11], and metabolic [12] health.

There’s no “arrival.” There’s no perfect pinnacle of personalized medicine. It’s an uphill trudge with small wins and losses. There’s always something to learn and improve and overcome.

What are some current obstacles?

For one, there are very few “single genes.”

Most disorders and diseases (like cancer) are polygenic, not monogenic. Most traits (like height or cognition) are polygenic, not monogenic. Rarely will you find a perfect 1:1 match. This makes drawing actionable inferences from genetic data difficult. The more variables there are, the harder it is to discern the signal from the noise. `

Data is accurate. Analysis is lacking.

The genetic testing itself is very accurate. If you swab your cheek and send it off to 23andMe or DNAFit or Ancestry, the raw data is likely accurate. Where things break down is the interpretation of the data. When a blogger ordered genetic tests from several different companies, she got mixed results. The data was identical, but how each company interpreted the data differed substantially [13].

I’ve spoken glowingly of DNAFit [14] in the past. And as far as the companies out there go, it’s probably the best one at analyzing the genetic data and providing actionable results. My own results matched what I’d experienced throughout my entire life of training and eating. And when the blogger notified DNAFit about some incongruities between their results and other companies’ results, they responded with a 2000 word justification of their interpretation of her data, complete with citations of the literature. The other companies either agreed to fix their mistakes or ignored her messages.

And, unfortunately, gut biome sequencing isn’t ready for prime time.

The gut biome is critical to our health [15]. Sequencing and analyzing the members of a person’s gut biome could help us predict interactions with drugs and foods. It could give us a roadmap for feeding specific prebiotics [16], polyphenols [17], and other nutrients to target specific gut bugs. We’d know which probiotics to take to fill in any gaps. We could target baddies with the right antibiotics [18], rather than firebombing the entire gut [19]. And we could compare our gut biomes to everyone else’s.

Unfortunately, popular testing services often differ in their results [20], and, assuming we have accurate results, they don’t tell us much about our health. We have rough associations between populations in the gut and some health conditions, but it’s not always consistent. Plus, we haven’t sequenced very many guts yet, so we’re flying blind.

The potential is clear. If we can identify all the genetic variants responsible for traits and untangle how they interact with environmental stimuli and lifestyle, we’ll have great control over our health and wellness. Throw in CRISPR [21], and things get even more interesting. We’re not quite there yet. There are lots of pieces, but they’re not in place.

It’s going to work though. Combining epigenetics, genetics, lifestyle, environment, the gut biome, ancestry, and high-powered technology will revolutionize medical care, nutrition, and fitness. I’m sure of it.

And as I’ve mentioned, personalized medicine is already viable in specific instances, like determining genetic drug tolerance and drug responsiveness, and identifying gene-disease associations. Is using your grandpa’s genetic data to determine his optimal coumadin dosage [22] sexy or exciting? No, but it’s legit and utilitarian. And it proves that personalized medicine has a future.

But for now?

You’re still responsible for eating right, moving every day, playing as much as you can, lifting heavy things, getting out into nature, and all the rest. You can’t abrogate your agency. The promise of personalized medical care indistinguishable from magic at some future date doesn’t change that. No surprises there, of course.

I’m curious. Have you (or those you love) used aspects of personalized medicine? What’s been your experience? And whether or not you’ve had the opportunity to apply it to your own care, what’s your take on the personalized medicine picture—and emerging possibilities? Are you excited? Skeptical? Hopeful?

Thanks for reading, everyone. Take care.