HUMAN GENETICS: THE LONG TERM FUTURE ISN’T THAT BLEAK
I have always admired the legend of Prometheus, who could see into the future and who shared his knowledge of science with humanity, a crime for which Zeus punished him.
Scientists are often promethean in their rash attempts to look into the future by seeing applications of their discoveries, and they are sometimes punished by their societies for saying things many do not wish to hear. Herman Muller and Linus Pauling, scientists I knew and admired, were like that. I cannot predict the future, of course, because I am not Prometheus. But, I can see some trends and problems that reflection about my science of genetics brings to my mind. I’ll share those with you.
The 21st century will be the century of the human genome project. With all 25,000 of our genes sequenced and their functions worked out, medicine will see new specialties arising especially for the treatment and prevention of genetic disorders. My prediction is that there will be more prevention than treatment because, for many disorders, the task of treatment would be like undoing scrambled eggs. But, prevention is controversial because it involves prenatal diagnosis and elective abortion. Right now, most of that controversy surrounds unwanted pregnancies for social reasons.
In the 21st century, the issue will shift because there will be far better means of family planning and birth control and thus, fewer social abortions and more based on medical conditions of the embryo. It also means there will be fewer surprises for couples intending to have children. Hundreds, if not thousands, of genetic disorders will be cheaply screened with technologies that are now at the planning stages using DNA microchips designed for different ethnic groups and the most common birth defects. The nature of elective abortion will also change as cases will be prenatally diagnosed during the first month of pregnancy, in many cases, by a blood test of the pregnant woman instead of by amniocentesis.
Two trends will be working in opposite directions. There will be a considerable reduction of disorders involving dominant mutations such as Huntington disease, achondroplastic, retinoblastoma, and Marfan syndrome because adults with these conditions will most likely use embryo screening by maternal blood test. This means the incidence of dominant mutations will plunge to their spontaneous mutation rates which is very low. For recessive disorders it is screened adults who will be making decisions about their children and I expect most of them will elect a healthy child who does not have that disorder. This will not diminish the incidence of the gene in the population because most of those infants, if born, will not live to reproductive maturity or have offspring. If curative methods are somehow developed, this will create long term problems because the genes that cause the problem are not altered by a satisfactory treatment for the symptoms of a disease. Those mutant genes will increase in the population each generation. At present we may have limited promethean foresight but no one can predict with confidence the long term values and behavior of our descendants centuries or millennia from now.