Eight years ago, this column featured a discussion of the status, futuristic implications, and ethical concerns of the field of medical genetics. Political and social changes, progress in the field, and new applications of genetic testing continue to make genetics a very important topic of great significance for all physicians and patients. An interesting presentation at a recent Avera Medical Education meeting reinforced that concept in discussing pharmaco-genetics, the science of examining how specific individuals interact with certain drugs.
Human Genetics is the study of the genome or the composition of the 46 human genetic chromosomes, the hereditary unit which makes each individual what he/she is. The moment of our conception determines a significant portion of our physical and mental makeup. It forms the basic unit which is then affected by the environment in which we are raised and live. Each year now brings us more information about how genetics, genetic testing and environment affect our lives.
Students of medical history are consistently impressed by the importance of genetic or inherited diseases and the role they have played in both our history in general and the events related to the evolution and development of medicine and medical care. Many examples are well known, but one that had a prominent role in Russian history strikingly portrays the significant role of a genetic disease in its effect on lives personal, family, national and global.
Although the causes and events leading to the Bolshevik Revolution in Russia in 1917 are complex and never clearly defined, many historians feel that the genetic illness and resultant poor health of the son of Nicholas II of the Romanov family and the subsequent harmful influence of the monk Rasputin on the leadership role of the Romanov family led to the revolution. This genetic illness was hemophilia, which Alexis inherited from his great-grandmother, Queen Victoria of Great Britain.
Not all inherited diseases are as prominent as hemophilia. However, interaction with any large group of people in our daily lives will reveal people with inherited disorders of several types. Findings such as achondroplasia (little people), albinism (lack of skin pigmentation), baldness, changes in skin pigmentation, and nevi (moles) exhibit the macroscopic or visible effects of our genetic expression. Although such changes have been noted since ancient times, only now are we on the threshold of specific therapy for some of these disorders.
As we mentioned in our last column, the field of medical genetics has progressed rapidly in the past century. The human blood groups (A, B, AB, and O) were discovered about 100 years ago, and sophistication of genetic testing rapidly developed after World War II. With the rapid progress in immunology and the description of the DNA structure in the 1950s, medical science can now combine with preventive medicine to begin to screen patients for those genetically related diseases. We now know that Cystic Fibrosis is a common genetically transmitted disease which may be treatable with genetic modifications.
Certain breast cancers and optimal therapies for these illness are often genetically determined. Although definitive and therapeutic treatment is anticipated in the future, discovery and treatment are essential to both the affected individual and prevention of its propagation in the human race.
Screening may be a cost-effective procedure that reviews all patients in a group to detect a treatable disease. At this time, no one screens patients for diseases which are untreatable such as Huntington's Chorea. Such procedures raise significant cultural, ethical and moral considerations. However, screening of specific groups can have very significant beneficial results.
In 2014, infants born in Minnesota are screened for more than 51 disorders that may impact an infant's metabolism, endocrine (gland) system, or blood physiology. These usually uncommon diseases include disorders as phenylketonuria (PKU), hypothyroidism (cretinism), cystic fibrosis, and very rare illnesses such as a disorder of amino acid metabolism featured in one of Patricia Cornwell's medical mysteries. The major types of conditions that newborn screening identifies include:
Disorders that affect how the body breaks down proteins (such as PKU)
Disorders that cause hormone problems (such as congenital hypothyroidism)
Disorders that cause blood problems (such as sickle cell disease, hemophilia)
Disorders that affect how the body makes energy (enzyme deficiencies)
Disorders that affect vital lung functions (cystic fibrosis)
If any of these characteristic disorders is detected at birth, medical care can modify the environment (diet), specifically treat the problem (thyroid replacement), and in all cases educate the parents as to the nature of the illness.
Screening has begun for cystic fibrosis, the most common inherited disease in the United States, in hope that gene replacement therapy can be therapeutic for this serious lung disease.
A somber consideration for all of us is outlined in a thoughtful discussion by editor Roy Porter in "The Cambridge Illustrated History of Medicine" (1996) when he states: "Greater longevity is certainly a factor in a greater frequency of some of the genetic diseases and genetic predisposition to other illnesses As some geneticists have argued, the principles of rigorous natural selection no longer apply."
As in other scientific disciplines, we as participants must continue to be educated, thoughtful, concerned and operative about our choices in these genetic matters and their effects on our society and our world.