Envirotyping: The Next Leap Forward in the Practice of Precision Medicine?

Precision medicine – prevention and treatment strategies that account for individual variability in genes, environment, and lifestyle – is not a new idea, but recent technological improvements in both patient characterization and in computational tools for analyzing large data sets have made it a short-term medical frontier.1 Deep-learning approaches, which utilizes artificial neural network and extensive computing powers to extract representative features from large data sets, are also increasingly being used to investigate the social and environmental determinants of health, which have received resurgent attention over the last decade.2 We propose that a reorientation toward envirotyping – the computation of a high-resolution, individualized exposure profile that is potentially the socio-environmental analog to genotyping – could facilitate our next leap forward in the practice of precision medicine. Through these technologies, real-time biometric data, such as heart rate, respiratory rate, oxygen saturation, body temperature, blood pressure and blood alcohol content, are collected along with geo-environmental data both static (e.g. physical location, including altitude when inside a multi-level building) and dynamic (e.g. distance and velocity of travel when inside a moving vehicle). Recently, three separate genome-wide studies showed significant association of certain alleles of LOXL1 (chromosome 15q24.1) with exfoliation glaucoma (XFG), with odds ratio ranging from 2- to 10-fold on average per-copy of the risk allele.6–8 Despite this robust genetic association, the XFG burden amongst pathogenic allele carriers varies with the latitude of residence, with higher disease burden positively correlated with the patient's distance from the equator.9,10 This implies that the pathogenic LOXL1 alleles contribute to the development of, but are not sufficient to cause, XFG, while the environmental factors related to residential latitude (e.g. ambient light, average temperature, etc.) may significantly modify the carrier phenotype and may in turn be moderated by additional socio-environmental factors.