“The Ins and Outs of Personalized Medicine”
Today Personalized Medicine is available, technically, and yet the infrastructure needed for full implementation is inadequate, the challenges are large, and society is unready for (perhaps even hostile to) what is possible.
The concept of Personalized Medicine is nevertheless intriguing. Most scientists have not considered how different one person is from another, nor even how different one set of cells in an individual is from a different set of cells in the same person. Personalized Medicine — “the right drug at the right dose at the right time for the right person” — faces the complexity of human biology. Just how different are any two people on the planet?
There are perhaps ~1033 different possible fertilized human eggs on the present earth, an astounding number. Six billion people provide 9 x 1018 potential mating pairs (as they are called, delicately) and each sperm and oocyte can contribute one of 8 x 106 (223) possible chromosome combinations to a fertilized egg. Additionally a fertilized egg divides perhaps 1014 times from embryo to adult, providing vast opportunities for somatic mutations that cause cancer and other diseases. That is, 1033 different possible fertilized human eggs have another 1014 cell divisions in which to progress, through mutations or environmental insults, toward disease.
Humans are different from laboratory mice. While humans seek out breeding opportunities, laboratory mouse strains are inbred to the point of being nearly identical at the level of DNA. This is one dilemma of Personalized Medicine – the Ins and the Outs. Genomic differences make us persons with a variety of medical conditions and destinies. We experiment on mice who are nearly identical, and then on humans who might as well be from different solar systems. Genomics matter greatly, yet the dimensionality of human genomics is staggering. One hopes (and can begin to see) that vastly different genomics push people toward diseases with common attributes that will be the Achilles heels for medical interventions.