Our humble genome

Recently, my daughter and I rewatched Jurassic Park, in which DNA extracted from mosquitoes was used to clone dinosaurs from extinction. Of course, the anachronistic juxtaposition of humans and prehistoric predators resulted in blockbuster evolutionary thrills. You would think vicious dinosaurs might inspire childhood nightmares, but don’t worry, my preteen daughter is firmly grounded in reality. Instead, she now has an intense fear of mosquitoes (those blood-sucking genetic thieves)!

The astute Modern Retina reader knows that the human genome has about 3 billion base pairs of DNA. Even with 99.9% similarity, we still have more than 3 million single nucleotide variants between us! The vast majority of these are not pathogenic but rather define our uniqueness. It’s humbling to consider the remarkable complexity of our cellular blueprints, especially when a single blip can cause blinding eye disease.

At this year’s Association for Research in Vision and Ophthalmology meeting, I was proud to see my Iowa colleagues, Drs Ed Stone and Val Sheffield, honored for their pioneering efforts in ophthalmologic genetics. In their Friedenwald Award lectures, they provided a 40-year perspective from foundational work to future promise. Whereas the Human Genome Project was once the greatest scientific achievement, genetic testing is now readily accessible, and we can identify pathologic variants in the majority of patients with inherited eye disease. Moreover, emerging therapies once considered science fiction, such as gene and stem cell therapies, are now reality on the clinical horizon.

However, as Dr Stone emphasized, access to genetic data does not obviate the need for clinical expertise but rather augments it. Such expertise is paramount for interpreting genetic tests in the proper context, counseling patients on prognosis, informing family planning, or guiding participation in clinical trials. Unlike in Jurassic Park, missteps in clinical genetic understanding likely won’t result in someone being devoured by a velociraptor. However, wielding such genetic data has its own perils without appropriate caution. For example, false negative genotypes are very common and can easily lead to the wrong diagnosis.

Unlocking the complexity of the human genome can lead to incredible innovations for human health, but doing so requires humility rather than hubris. In that vein, while I hope humans endure for eternity, maybe eons from now a future species will find our DNA preserved in mosquitoes. At least that’s what I tell my daughter every time she is bothered by a bug bite: “Don’t worry, it’s for science!” (But maybe next time, wear bug spray.)

No financial disclosures

Ian C. Han, MD

Beisner Professor of Vitreoretinal Diseases and Surgery

Director, Retina Service

Institute for Vision Research

Department of Ophthalmology and Visual Sciences

University of Iowa Hospitals and Clinics